Effects of cassava root meal on the growth performance, apparent nutrient digestibility, organ and intestinal indices, and slaughter performance of yellow-feathered broilers

Effects of cassava root meal on the growth performance, apparent nutrient digestibility, organ and intestinal indices, and slaughter performance of yellow-feathered broilers | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Effects of cassava root meal on the growth performance, apparent nutrient digestibility, organ and intestinal indices, and slaughter performance of yellow-feathered broilers Yajin Yang, Fuhong Lei, Zubing Zhang, Lily Liu, Qingqing Li, Aiwei Guo This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3984805/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 24 Sep, 2024 Read the published version in Tropical Animal Health and Production → Version 1 posted 5 You are reading this latest preprint version Abstract To investigate the effects of cassava root meal (CRM) on the growth performance, apparent digestibility, and organ and intestinal indices of broilers. A total of 140 one-day-old chicks were randomly assigned to one of four dietary treatment groups [control diet (CT), 15% CRM (CRM15), 30% CRM (CRM30), and 45% CRM (CRM45)] with five replicates of seven birds per replicate. The Results showed that the body weight of broilers in the CRM groups was significantly lower than that in the CT group at 21 and 42 days of age, and the average daily gain and average daily feed intake in the CRM group were significantly lower than those in the CT group from 1 to 21 days of age. However, from days 22 to 42, there were no significant differences between CRM15 and CT birds regarding average daily gain and average daily feed intake. but there was no difference in feed conversion rate between the CRM15 and CT groups. At 42 days of age, there were no significant differences between CRM15 and CT birds in in body measurements, the slaughter performance and semi-evisceration ratio. The addition of CRM reduced the proportion of breast and thigh muscles during the feeding period, although we detected no significant difference between CRM15 and CT regarding the apparent digestibility of nutrients. Collectively, our findings indicate that 15% cassava was the optimal proportion for supplementing diets for broiler production. cassava root meal growth performance apparent digestibility organ index broiler Figures Figure 1 Figure 2 Figure 3 Introduction The global shortage of livestock feed resources is a common problem, with the animal feed industry being heavily reliant on corn, which provides 60–70% of animal energy requirements (Ahiwe et al. 2018 ). With the current expansion of the livestock sector and continual world population growth, competition for food between humans and livestock has become an increasingly prominent issue, particularly in developing countries. Consequently, it is important to assess alternative energy sources that could be used to replace corn. Cassava ( Manihot esculenta ) is a widely consumed staple food grown in tropical and subtropical regions. Notably, it can be cultivated without fertilizer in dry, poor, and acidic soils that are unsuitable for growing corn and other crops (Pradyawong et al. 2018 ). Sixty-one percent of the global cassava crop is produced in Africa, with smaller proportions of 29% and 9% being grown in Asia and South America, respectively (FAO 2018 ). Compared with corn, cassava has the highest yield per unit land area of 25–60 t /hm 2 , and cassava meal has lower production costs and a higher starch content (70–80%), also has potential to partially replace corn in poultry feed (Garcia and Dale 1999 , Rolland-Sabate et al. 2012, Chang'a et al. 2020). To date, however, the use of cassava in conventional feeds has been limited by certain factors. notably the low contents of essential amino acids and high levels of cyanogenic glycosides (Tiwari and Jha 2016 ). In particular, the lack of methionine and lysine in cassava necessitates a close consideration of the nutritional profiles of feed formulations (Oke 1978 ). Nevertheless, Adeyemi et al. ( 2008 ) overcames the problem of low amino acid contents by supplementing broiler diets with synthetic amino acids, whereas the cyanogenic glycoside contents in cassava can be reduced by applying appropriate processing methods such as soaking, sun drying, boiling, and fermentation (Omede et al. 2018 ), among which, sun drying has been found to be more effective than oven-drying in a number of studies (Tewe, 2004, Panigrahi S et al. 1992 , Gomez et al. 1984 ). As an energy source in poultry feed, numerous studies have assessed the effects of replacing corn meal with cassava or pretreated cassava, with the aim of optimizing the supply of glucose and enhancing absorption efficiency (Chukwukaelo, 2018, Alade et al. 2020 , Okrathok et al. 2022). The amylopectin content in cassava is digested and absorbed more rapidly in the form of glucose than is amylose, which can be attributed to the facts that amylopectin readily gels and has a larger surface area for digestive enzyme activity (Martens 2019 , Zhou et al. 2021 ). Consequently, the incorporation of cassava in livestock diets can contribute to optimizing glucose supply and enhancing absorption efficiency. Notably, however, the benefits of supplementing poultry diets with cassava tend to be variety dependent, and thus nutrient determinations and feeding studies are needed to establish the appropriate proportions of dietary supplementation. In this regard, Picoli et al. ( 2014 ) revealed that slow-growing broiler diets containing 10% cassava had no negative effects on carcass yield or abdominal fat deposition, whereas da Silva et al. ( 2019 ) has reported that the inclusion of dry residues of cassava in broiler diets affected breast yield, with the maximum addition estimated at 4.06%. Although the aforementioned studies have shown that the inclusion of cassava concentrate in broiler diets has potential benefits when nutrients are correctly balanced, the effects can differ depending on the appropriate proportions of different sources of cassava, broiler species, and treatment methods. To date, however, there have been no systematic studies that have examined the effects of replacing corn with cassava on the production performance, nutrient digestibility, and intestinal development of broilers. Accordingly, in this study, we aimed to investigate the effects of cassava root meal (CRM) as a substitute for maize on the growth performance, apparent digestibility of nutrients, organ and gastrointestinal tract indices, and slaughter performance of broilers from 1 to 42 days of age. Our findings will provide useful information for guiding the use of cassava as an alternative energy source, and thereby go some way to alleviating the competing requirements of humans and livestock for food. Materials and Methods Animals and housing A total of 140 one-day-old male yellow-feathered broilers were acquired from a commercial hatchery in Kunming, China. The birds were randomly assigned to four treatment groups, each with five replicates, and seven birds per replicate. All experimental procedures received approval from the Academic Committee of Southwest Forestry University. Throughout the initial week of the 42-day trial, the room temperature was kept within the range of 32–35°C using air conditioning. Subsequently, it was gradually reduced to 24°C by day 21 and maintained at that level for the remainder of the trial. The chicks were raised in cages under constant illumination throughout the study period, with ad libitum access to both food and water. C assava root meal preparation and broiler diets The cassava SC9 variety used in this study is a widely cultivated high-yielding low-cyanogenic glycoside variety bred in Yunnan Province. To prepare the CRM, the roots were initially washed and then sliced, sun-dried, and crushed. The chemical composition of the CRM, determined using AOAC- recommended methods (AOAC 2012 ), was as follows: starch, 75.12%; crude protein, 4.45%; ether extract, 0.95%; crude fiber, 4.63%; ash, 4.14%; nitrogen-free extract, 85.83%; calcium, 0.22%; phosphorus, 0.16%; cyanogenic glycoside, 0.9 mg/kg; tannin, 470 mg/kg, and L (+)-ascorbic acid, 28.8 mg/100 g. From day one, the birds were subjected to one of the following four dietary treatments: a basal diet as the control (CT), and three diets in which corn was replaced with 15% (CRM15), 30% (CRM30), or 45% (CRM45) cassava root meal (Fig. 1 ). The diets were formulated in accordance with the recommendations of the National Research Council (NRC 1994 ) and the nutrient requirements of yellow-feathered broilers (MAC 2017), as shown in Table 1 . Table 1 Ingredient composition and calculated nutrient levels of the experimental diets Items 1 Treatments 1 CT CRM15 CRM30 CRM45 Ingredients (%) Corn 60.00 45.00 30.00 15.00 Cassava root meal (ME, 14.47 MJ/kg) 2 0.00 15.00 30.00 45.00 Soybean meal (43% CP) 26.22 25.95 26.07 25.79 Fish meal (65% CP) 5.60 6.80 7.80 8.70 Corn protein meal (50% CP) 2.00 2.00 2.00 2.00 Soybean oil 1.90 1.30 0.50 0.00 L -Lysine 0.05 0.05 0.00 0.00 DL -Metonine 0.22 0.23 0.25 0.25 Limestone 1.25 1.25 1.22 1.30 Dicalcium phosphate 1.20 0.90 0.60 0.40 Sodium chloride 0.30 0.30 0.30 0.30 Vitamin and mineral premix 3 1.00 1.00 1.00 1.00 Choline chloride (50%) 0.26 0.22 0.26 0.26 Total 100.00 100.00 100.00 100.00 Calculated nutrient content 2 ME (MJ/kg) 12.40 12.45 12.44 12.49 Crude protein (%) 21.13 21.14 21.19 21.00 Ether extract (%) 4.93 3.98 2.84 1.97 Crude fibre (%) 1.90 2.26 2.64 3.01 Lysine (%) 1.21 1.23 1.20 1.20 Methionine + Cys (%) 0.92 0.91 0.91 0.88 Calcium (%) 1.03 1.03 1.01 1.05 Nonphytate phosphorus (%) 0.49 0.48 0.47 0.47 Cyanogenic glycoside (mg/kg) 0.00 0.14 0.27 0.41 1 CT = Control (0% CRM supplement); CRM 15 = 15% CRM supplement; CRM 30 = 30% CRM supplement; CRM 45 = 45% CRM supplement. 2 Calculated based on analysis of raw materials (Dale N 1996 ). 3 The premix is supplied with the following per kilogram of diet: Vitamin A, 8000; IU; Vitamin D3, 1000 IU; Vitamin E, 20 mg; Vitamin K3, 0.5 mg; Vitamin B1, 2 mg; Vitamin B2, 8 mg; Vitamin B6, 3.5 mg; niacin, 35 mg; biotin, 0.18 mg; Folic acid, 0.55 mg; pantothenic acid, 10 mg; Manganese, 100 mg; Zinc, 80 mg; Iron, 80 mg; Copper, 9 mg; Iodine, 0.35 mg; Selenium,0.15 mg. Growth performance and body measurements Throughout the study period, the body weight (BW) and feed intake (FI) of broilers were measured at weekly intervals. Feed intake was calculated as the difference between the feed offered and that remaining unconsumed. The feed conversion ratio (FCR) was computed as the ratio of feed consumed to weight gain. At 21 and 42 days of age, body measurements (keel length, breast depth, breast width, hip width, shank length, and shank circumference) of each bird were obtained according to the methods recommended by the Chinese National Poultry Breeding Committee (CNPBC 1984). Apparent digestibility of nutrients The apparent digestibility of nutrients was determined using a total excreta collection procedure (Khalil et al. 2021 ). The feed intake and total excreta output for each replicate cage were recorded over the final four consecutive days of the study. Excreta from each cage were collected and extraneous material, such as feathers, was removed. The excreta was subsequently sprayed with hydrochloric acid diluent (V/V, 1:3) and dried at 60°C, after which it was ground and stored for further analysis. To assess the apparent digestibility of broilers, sample of the diets and excreta were analyzed for determinations of dry matter, crude protein, ether extract, and crude ash using standard methods (AOAC 2012 ). Organ and gastrointestinal tract indices and slaughter performance At 42 days of age, two birds from each replicate (40 birds in total) with representative mean body weights were selected for slaughter. Prior to slaughter, the birds were fasted overnight, feathers and internal organs were removed to evaluate slaughter performance using methods recommended by the Chinese National Poultry Breeding Committee (CNPBC 1984). The following organs and intestinal segments were separated and weighed, with weights being expressed as a ratio to the living BW: liver, spleen, thymus, bursa, heart, pancreas, proventriculus, gizzard, duodenum, jejunum, ileum, and rectum. In addition, the weights of the carcass, semi-evisceration, evisceration, breast muscle, and thigh muscle were recorded and expressed as a ratio to the living BW. Statistical analysis The statistical model included the level of CRM supplementation as a treatment effect. Data were analyzed by one-way ANOVA analysis using the General linear model program of SPSS 21.0. The significance of differences between groups determined using Tukey’s test. All statistical analyses were declared significantly different at a P -value of less than 0.05. Results Growth performance and body measurement indices Table 2 shows the effects of CRM supplementation on the growth performance of broilers. From 1 to 21 days of age, the body weight (BW), average daily gain (ADG), and average daily feed intake (ADFI) of broilers in the CRM groups were found to be significantly lower than those in the CT ( P < 0.05). From 22 to 42 days of age, the BW of CT birds was significantly higher than that in the CRM groups ( P < 0.05) whereas we detected no significant differences between the CRM15 and CT with respect to ADG, ADFI, and FCR. Throughout the experimental period (1–42 days of age), we recorded higher FCR values among birds in the CRM30 and CRM45 compared with those in the CT and CRM15. As body measurements, we assessed six traits, all of which had declined significantly with an increase in supplemental CRM compared with those in control birds when measured at 21 days of age ( P < 0.05) (Table 3 ). At 42 days of age, we detected no significant differences between the CT and CRM15 birds with respect to keel length, breast width, hip width, and shank length, whereas the values for these traits in CRM30 and CRM45 birds were significantly lower than those in the CT ( P < 0.05). Table 2 Effect of dietary CRM supplementation on growth performance of broilers Items Days of age Treatments SEM P- Value CT CRM15 CRM30 CRM45 BW (g) 1 39.30 39.31 38.69 39.37 0.19 0.569 21 486.79 a 439.12 b 421.37 b 379.29 c 9.85 < 0.001 42 1371.74 a 1282.81 b 1212.80 b 1094.68 c 26.92 < 0.001 ADG (g/d) 1–21 25.16 a 22.29 b 20.78 b 18.18 c 0.66 < 0.001 22–42 42.14 a 40.18 a 37.69 ab 34.07 b 0.98 0.001 1–42 35.35 a 33.02 ab 30.62 b 27.71 c 0.76 < 0.001 ADFI (g/d) 1–21 45.50 a 41.05 b 40.91 b 38.05 c 0.63 < 0.001 22–42 91.81 a 88.43 a 87.27 ab 82.84 b 1.03 0.008 1–42 68.66 a 64.16 b 64.67 b 60.44 c 0.78 < 0.001 FCR 1–21 1.81 b 1.84 b 1.98 ab 2.11 a 0.04 0.030 22–42 2.18 2.23 2.32 2.47 0.06 0.316 1–42 1.94 b 1.95 b 2.09 ab 2.19 a 0.04 0.019 CT = Control (0% CRM supplement); CRM15 = 15% CRM; CRM30 = 30% CRM; CRM45 = 45% CRM. Means with different superscript letters within a row are significantly different ( P < 0.05). SEM standard error of means. Table 3 Effect of dietary CRM supplementation on body measurements of broilers Items Body measurements CT CRM15 CRM30 CRM45 SEM P- Value 21 days of age Keel length (cm) 8.00 a 7.58 b 5.80 c 5.36 d 0.26 < 0.01 Breast depth (cm) 6.88 a 6.26 b 5.56 c 4.40 d 0.22 < 0.01 Breast width (cm) 6.16 a 5.18 b 4.72 c 4.12 d 0.18 < 0.01 Hip width (cm) 6.06 a 5.56 b 4.90 c 4.43 d 0.15 < 0.01 Shank length (cm) 6.76 a 6.07 b 6.06 b 5.40 c 0.12 < 0.01 Shank circumference (cm) 3.47 a 3.30 b 3.07 c 3.09 c 0.04 < 0.01 42 days of age Keel length (cm) 12.20 a 11.25 a 9.14 b 8.71 b 0.37 < 0.01 Breast depth (cm) 8.72 8.53 8.44 8.04 0.14 0.351 Breast width (cm) 9.62 a 9.71 a 8.55 b 7.27 c 0.25 < 0.01 Hip width (cm) 10.07 a 9.61 a 8.12 b 8.42 b 0.20 < 0.01 Shank length (cm) 10.00 a 10.07 a 8.03 b 8.53 b 0.24 < 0.01 Shank circumference (cm) 4.49 ab 4.65 a 4.22 c 4.29 bc 0.06 0.008 CT = Control (0% CRM supplement); CRM15 = 15% CRM; CRM30 = 30% CRM; CRM45 = 45% CRM. Means with different superscript letters within a row are significantly different ( P < 0.05). SEM standard error of means. Apparent digestibility of nutrients The results obtained for the apparent digestibility of nutrients are shown in Fig. 2 . From 39 to 42 days of age, we detected no significant differences between the CRM15 and CT birds regarding the apparent digestibility of dry matter, crude protein, ether extract, or crude ash ( P > 0.05), whereas in response to dietary supplementation with 30% and 45% CRM, there was a significant reduction in the apparent digestibility of dry matter, crude protein, and ether extract ( P 0.05). Organ and gastrointestinal tract indices As shown in Table 4 , among the assessed organ indices of 42-day-old broilers, the heart index of CRM30 birds was significantly lower than that of birds in the other three groups ( P < 0.05), whereas the thymus indices of the CRM30 and CRM45 group birds was slightly higher than that of birds in the other groups. Otherwise, we detected no appreciable differences among groups with respect the other organ indices (liver, spleen, bursa, and pancreas) ( P > 0.05). Among the assessed gastrointestinal tract indices, those for the jejunum and ileum in the CRM35 and CRM45 birds were significantly lower than those in the CT birds ( P < 0.05), whereas there was little difference between the CRM15 and CT groups with respect to jejunum index (Table 5 ). Apart from these difference, we detected no significant differences among the groups with respect to other gastrointestinal tract indices (i.e., proventriculus, gizzard, duodenum, and cecum ( P > 0.05). Table 4 Effect of dietary CRM supplementation on organ index of broilers at 42 days of age Items CT CRM15 CRM30 CRM45 SEM P- Value Liver, g/kg 20.97 20.99 19.34 21.01 0.50 0.557 Spleen, g/kg 2.14 1.98 1.86 1.98 0.09 0.718 Thymus, g/kg 6.08 5.73 6.40 6.86 0.18 0.187 Bursa, g/kg 2.89 2.39 2.47 2.41 0.09 0.111 Heart, g/kg 7.08 a 6.74 a 5.43 b 6.07 ab 0.21 0.009 Pancreas, g/kg 2.52 2.22 2.08 2.26 0.08 0.217 CT = Control (0% CRM supplement); CRM15 = 15% CRM; CRM30 = 30% CRM; CRM45 = 45% CRM. Means with different superscript letters within a row are significantly different ( P < 0.05). SEM standard error of means. Table 5 Effect of dietary CRM supplementation on gastrointestinal tract index of broilers at 42 days of age Items CT CRM15 CRM30 CRM45 SEM P- Value Proventriculus, g/kg 5.00 4.72 4.91 4.63 0.12 0.711 Gizzard, g/kg 20.04 16.92 17.79 16.83 0.61 0.204 Duodenum, g/kg 8.02 7.19 7.03 6.76 0.26 0.397 Jejunum, g/kg 10.01 a 9.31 ab 9.04 b 8.84 b 0.14 0.019 Ileum, g/kg 10.41 a 9.39 b 9.28 b 8.72 b 0.19 0.016 Cecum, g/kg 5.39 5.25 5.73 5.72 0.15 0.616 Rectum, g/kg 2.72 2.17 2.19 2.02 0.11 0.140 CT = Control (0% CRM supplement); CRM15 = 15% CRM; CRM30 = 30% CRM; CRM45 = 45% CRM. Means with different superscript letters within a row are significantly different ( P < 0.05). SEM standard error of means. Slaughter performance Results for the slaughter performance of broilers at 42 days are presented in Fig. 3 . These reveal significant reductions in the slaughter indices (slaughter ratio, breast muscle ratio, and thigh muscle ratio) of birds fed CRM diets compared with the CT birds ( P < 0.05). However, we detected no significant differences between the CRM15 and CT groups in terms of semi-evisceration and evisceration ratios, although compared with the control group, cassava supplementation was associated with significant reductions in the proportions of breast and thigh muscles at 42 days of age ( P < 0.05). Discussion Cassava, characterized by a high productivity per unit area, is one of the three major tuber crops cultivated worldwide, and is considered an effective source of energy for livestock production (Rolland-Sabaté et al. 2012 , Li et al. 2017 ). However, the widespread use of cassava in livestock feed has been limited on account of its low levels of certain essential amino acids and high hydrocyanic acid content (Tiwari and Jha 2016 ). However, Falade and Akingbala ( 2010 ) have confirmed that adequate drying can reduce the concentrations of hydrocyanic acid in cassava to acceptable levels. In this study, we used the SC9 variety of cassava, which has been established to be a low cyanogenic glycoside (0.9 mg/kg) variety. The levels of cyanogenic glycoside in the feed formulae calculated in this study ranged from 0.14 to 0.41 mg/kg, which meet the requirements for cyanogenic glycoside contents outlined in the feed hygiene standards of China (< 100 mg/kg) (MAC 2017). The performance of broilers fed cassava diets varied depending on the level of cassava content in their diet. Gomez et al. ( 1984 ) have reported that supplementation of broiler diets with 30% CRM had no appreciable adverse effects on the body weights of birds. Similarly, weight gain was not affected in chickens fed 10% cassava leaf meal (Bakare et al. 2020), 20% cassava peel meal (Oyebimpeet al. 2006 ), 60% composite cassava meal (Ukachukwu 2008 ). Contrastingly, in the present study, we detected significant reductions in the BW, ADG, and ADFI of broilers during the initial period (1–21 day) of feeding on CRM-supplemented diets. Compared to corn with a crude protein level of 8%-9% (Koehler and Wieser 2013 ), dried cassava is characterized by low protein contents (4.45%) and high levels of fiber (4.63%), which would limit nutrient digestion in the small intestines of poultry (Aro et al. 2008 , Raphaël et al. 2012 ). These observations reflect the relatively the poor ability of chicks to digest cassava early in life, as at this stage their digestive tract have yet fully develop. However, during the latter stages of the trial (22–42 days), these detrimental effects became increasingly less apparent in the CRM15 broilers. Similarly, Yadav also observed a linear reduction in the BW of chicks fed diets supplemented with 37.5% and 50% cassava during the starter periods, whereas these high levels of cassava had little effect on ADG and ADFI during the latter phase of growth (Yadav et al. 2019 ). Throughout the 42 d feeding period in this study, we found that the FCR of birds in the CRM15 was similar to that of CT birds, although supplementation with CRM had an negative influence on the weight gain of broilers. A well-developed gut is essential for the efficient utilization of cassava, as high levels of starch and fiber evades digestion in the small intestine and passes to the large intestine, wherein it is fermented by the gut microbiota (Oladunmoye et al. 2014 , Jha and Berrocoso 2015 ). These high fiber and starch contents of cassava may play a prebiotic role in the fully developed hindgut segment. However, birds in the CRM30 and CRM45 were characterized by lower values for BW and body measurements, which would accordingly lead to longer rearing times and higher feed consumption. Previous studies have also found that supplementation with higher levels of CRM in broilers delayed weight gain (Ochetim 1991, Ru et al. 2012 ). Similar to this study, dietary CRM supplementation was observed to retard the growth of broilers during the early stage (1–21 days) of the feeding trial, whereas the body measurements of CRM15 birds were not significantly different from those of CT birds during the latter stage of the trial (22–42 days), thereby indicating that the growth of CRM15 broilers substantially improved with a prolongation of the period during which they fed on a CRM-supplemented diet. Despite the fact that body measurements closely reflect poultry growth, development, and flock uniformity, particularly in intensive poultry production systems, the effects of CRM on the body measurements of broilers has rarely been reported (He et al. 2021 ). In the present study, we established that whereas supplementing broiler diets with CRM15 had no appreciable adverse effects on the growth or development of broilers, the use of high levels of CRM (30% and 45%) had negative effects on broiler growth and body measurements. Study have shown that apparent digestibility is reduced when corn is substituted with more than 30% cassava, and that feeding dried potato pulp at 25% also reduces nutrients apparent digestibility and retention (Khempaka et al. 2016 ). In the present study, we found that replacing corn with 30% and 45% cassava contributed to significant reductions in the apparent digestibility of dry matter, crude protein, and ether extract in broilers. However, substitution ratio of 15% showed no significant difference compared to the CT broilers. This effect could be attributable to the fact that cassava is rich in non-starch polysaccharides (NSP), which are mostly insoluble. In this regard, the concentration of water-soluble NSP in cassava root was lower (0.078% ~ 1.64%) than that in maize (8.4%) and soybean (9.8%) (Meng and Slominski 2005 , Chauynarong et al. 2015, Uthumporn et al. 2017 ). Insoluble NSP reduces the efficient digestion of nutrients by interfering with the action of amylase and protease (Morgan et al. 2016). Nevertheless, these SNP in cassava can serve as a substrate for microbial fermentation, which influences the production of short-chain fatty acids (Canfora and Blaak 2017 ), which, along with glucose, are essential nutrients for metabolic conversions in the body. The main amino acids found in cassava root are glutamine, alanine, and asparagine, while the content of methionine and cysteine, which are key essential amino acids in poultry diet, is relatively low (Morgan et al. 2016). The low protein content of cassava root makes it a significant disadvantage for its use in poultry feed. Furthermore, the co-ingestion of glucose and amino acids has been shown to have a synergistic effect in potentiating insulin secretion and subsequently stimulating muscle protein synthesis (Van Loon et al. 2000 ). Accordingly, supplementing feed with amino acids or subjecting cassava to fermentation are considered effective approaches to enhancing the nutritional value of supplemental cassava, as has been confirmed by some studies (Aladi et al. 2021 , Chang'a et al. 2020, Diarra and Anand 2020 ). Dietary constituents can influence the structure of the digestive tract and the passage of digesta through the gastrointestinal tract. For example, the intake of roughage has the effect of promoting increased muscle activity in the gizzard, thereby contributing to a gain in weight, and maximizing the grinding ability of the gastrointestinal tract (Jacobs and Parsons, 2013). Indeed, it has been demonstrated that the gizzards of broilers fed coarse diets were 15% heavier than those of birds fed fine diets. Furthermore, high-protein diets have been found to reduce intestinal villus height/crypt depth and butyric acid production. Guo et al. ( 2018 ) has also reported that the digestive tract weight indices of the gizzard and rectum increased in birds fed a diet supplemented with pine needle powder. Similarly, svihus ( 2011 ) found that consumption of feed containing structural components, such as hulls, wood shavings, or large cereal particles, can contribute to a rapid and significant enlargement in the size of the gizzard. In the present study, we found that supplementing diets with CRM had no significant effects on the indices of the proventriculus and gizzard of broilers at 42 days of age, although contributed to reduction in the indices of the jejunum and ileum, which could plausibly be attributed to the crude fiber content of the cassava (4.63%) used to supplement the diets, which was not sufficient to alter the weight of the gastrointestinal tract. Similar to the findings of previous studies that have reported that supplementing the diet of slow-growing broilers with 10% cassava had no significant effects on carcass or growth performance (da Silva et al. 2019 , Almeida et al. 2020 ), we found that when broilers were fed a diet in which corn was replaced with 15% cassava, there was no significant differences in the rates of semi-evisceration and evisceration in the broilers compared with the controls, and no significant difference in the organ indices of groups. However, differences in the other slaughter indices were mainly reflected in the proportions of breast and thigh muscles. It can thus be speculated that the observed differences in carcass yield may be associated with the balance of amino acids in the diet. It has, for example, been established that the amounts and proportions of methionine and lysine are directly linked to carcass and slaughter yields, particularly with respect to muscle tissue, which accounts for approximately 50% of total carcass protein. Similarly, the findings of previous studies have indicated that substitution with 10–16% cassava had no appreciable effects on the muscle mass of poultry, whereas substituting maize with 40% CRM had the effect of reducing breast yield (Omede et al. 2018 , Khempaka et al. 2016 ). Given that rapid protein deposition is dependent on efficient nutrient conversion, low-protein cassava supplementation may be more appropriate for the growth of slow-growing broilers. Further studies are required to examine the synergistic promotion effect of the proportional composition of nutrient. In this study, we found that replacing corn in the diets of yellow-feather broilers with 15% cassava root meal did not significantly influence the production performance, rate of nutrient digestibility, slaughter performance, or gastrointestinal tract indices of broilers chicks compared with control birds. In addition, the substitution is best done at a later stage. In contrast, high levels of dietary cassava can inhibit the production performance, nutrient digestibility, and slaughter performance of these broilers. Accordingly, our findings indicate that when supplemented at appropriate levels, cassava root meal, as an alternative high-yield inexpensive energy feed source, may be feasible and effective in broiler production. Declarations Acknowledgements We also would like to thank Editage (www.editage.cn) for English language editing. Ethics approval This study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the Ethics Committee of Southwest Forestry University. Consent to participate Not applicable. Consent for publication Not applicable. Competing Interests The authors declare no competing interests. Funding This work was supported by [Science Research Foundation Project of Yunnan Education Department under Grant [number 2022J0504]; [National Natural Science Foundation of China under grant number 31860650, 31460609]; [National Cassava Industry Technology System Xishuangbanna Comprehensive Experimental Station Project under Grant CARS-11-YNLHHQ]; The Key Laboratory of Forest Biotechnology in Yunnan, Southwest Forestry University; The Scientific and Technological Innovation Team Construction Project for Protection and Utilization of Under-forest Biological Resources in Universities of Yunnan Province. Author Contributions All authors participated in the study conception and design. Material preparation, data collection and analysis were performed by all the authors. The first draft of the manuscript was written by Yajin Yang and Aiwei Guo edited the manuscript. All authors read and approved the final manuscript. Data availability Data will be made available on reasonable request. References Adeyemi, O.A., Eruvbetine, D., Oguntona, T., Dipeolu, M.A., Agunbiade, J.A. 2008. Feeding broiler chicken with diets containing whole cassava root meal fermented with rumen filtrate. Archivos de Zootecnia. 57(218), 247-258. Ahiwe, E.U., Omede, A.A., Abdallh, M. B., Iji, P.A. 2018. Managing Dietary Energy Intake by Broiler Chickens to Reduce Production Costs and Improve Product Quality. In Animal Husbandry and Nutrition(IntechOpen,London). https://doi.org/10.5772/intechopen.76972. Alade, A.A., Bamgbose, A.M., Oso, A.O., Adewumi, B.A., Jegede, A.V., Anigbogu, N.M., Ogunsola, I.A. 2020. 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Nutritive values of corn, soybean meal, canola meal, and peas for broiler chickens as affected by a multicarbohydrase preparation of cell wall degrading enzymes. Poultry Science, 84, 1242–1251. https://doi.org/10.1093/ps/84.8.1242. Ministry of Agriculture of China (MAC). 2017. Feeding Standard of chicken. In Hygienical standard for feeds GB13078-2017, (Standards Press of China, Beijing). Morgan, N.K., Choct, M. 2016. Cassava: Nutrient composition and nutritive value in poultry diets. Animal Nutrition, 2, 253–261. https://doi.org/10.1016/j.aninu.2016.08.010. NRC. 1994. Nutrient requirements of poultry. In United States National Research Council, 9th ed, (National Academy Press, Washington). Ochetim, S. 2014. The use of cassava in broiler feeding in the south pacific. Asian-Australasian Journal of Animal Sciences, 4, 241–244. https://doi.org/10.5713/ajas.1991.241. Oke, O.L. 1978. Problems in the use of cassava as animal feed. Animal Feed Science and Technology, 3, 345–380. https://doi.org/10.1016/0377-8401(78)90009-3. Okrathok, S., Sirisopapong, M., Mermillod, P., Khempaka, S. 2023. Modified dietary fiber from cassava pulp affects the cecal microbial population, short-chain fatty acid, and ammonia production in broiler chickens. Poultry Science, 102, 102265. https://doi.org/10.1016/j.psj.2022.102265. Oladunmoye, O.O., Aworh, O.C., Maziya-Dixon, B., Erukainure, O.L., Elemo, G.N. 2014. Chemical and functional properties of cassava starch, durum wheat semolina flour, and their blends. Food Science & Nutrition, 2, 132–138. https://doi.org/10.1002/fsn3.83. Omede, A.A., Ahiwe, E.U., Zhu, Z.Y., Fru-Nji, F., Iji, P.A. 2018. Improving Cassava Quality for Poultry Feeding Through Application of Biotechnology. In Cassava(intechopen, Rijeka). https://doi.org/10.5772/intechopen.72236. Oyebimpe, K., Fanimo, A.O., Oduguwa, O.O., Biobaku, W.O. 2006. Response of broiler chickens to cassava peel and maize offal in cashewnut meal-based diets. Archivos De Zootecnia, 55, 301-304. Panigrahi, S., Rickard, J., O’brien, G.M., Gay, C. 1992. Effects of different rates of drying cassava root on its toxicity to broiler chicks. British Poultry Science, 33, 1025-1041. https://doi.org/10.1080/00071669208417545. Picoli, K.P., Murakami, A.E., Nunes, R.V., do Amaral Duarte, C.R., Eyng, C., Ospina-Rojas, I.C. 2014. Cassava starch factory residues in the diet of slow-growing broilers. Tropical Animal Health and Production, 46, 1371–1381. https://doi.org/10.1007/s11250-014-0649-7. Pradyawong, S., Juneja, A., Sadiq, M., Noomhorm, A., Singh, V. 2018. Comparison of Cassava Starch with Corn as a Feedstock for Bioethanol Production. Energies, 11, 3476. https://doi.org/10.3390/en11123476. Raphaël, K., Fulefack, H.D., Gandjou, H.M., Ngouana, R., Noubissie, M.M., Ninjo, J., Teguia, A. 2012. Effect of cassava meal supplemented with a combination of palm oil and cocoa husk as alternative energy source on broiler growth. Archiva Zootechnica,15, 17e25. Rolland-Sabaté, A., Sánchez, T., Buléon, A., Colonna, P., Jaillais, B., Ceballos, H., Dufour, D. 2012. Structural characterization of novel cassava starches with low and high-amylose contents in comparison with other commercial sources. Food Hydrocolloids, 27, 161–174. https://doi.org/10.1016/j.foodhyd.2011.07.008. Ru, Y.J., Tang, D.F., Song, S.Y., Choct, M., Iji, P.A. 2012. The Effect of Cassava Chips, Pellets, Pulp and Maize Based Diets on Performance, Digestion and Metabolism of Nutrients for Broilers. Journal of Animal and Veterinary Advances, 11, 1332–1337. https://doi.org/10.3923/javaa.2012.1332.1337. da Silva, I.M., Broch, J., Wachholz, L., de Souza, C., Dalolio, F.S., Teixeira, L.V., Eyng, C Nunes, R.V. 2019. Dry Residue of Cassava Associated With Carbohydrases in Diets for Broiler Chickens. Journal of Applied Poultry Research, 28, 1189–1201. https://doi.org/10.3382/japr/pfz085. Svihus, B. 2011. The gizzard: function, influence of diet structure and effects on nutrient availability. World’s Poultry Science Journal, 67, 207–224. https://doi.org/10.1017/s0043933911000249. Tewe, O.O., Fao, R., Lutaladio, N. 2004. Cassava for livestock feed in sub-Saharan Africa. Rome, Italy: FAO. Tiwari, U.P., Jha, R. 2016. 0992 Nutrient profile and in vitro digestibility of cassava silages in swine. Journal of Animal Science, 94, 475–476. https://doi.org/10.2527/jam2016-0992. Ukachukwu, S.N., 2008. Effect of composite cassava meal with or without palm oil and/or methionine supplementation on broiler performance. Livestock Research for Rural Development, 20, 53. Available from http://www.lrrd.org/lrrd20/4/ukac20053.htm. Uthumporn, U., Nadiah, I., Izzuddin, I., Cheng,L.H., Aida, H. 2017. Physicochemical Characteristics of Non-Starch Polysaccharides Extracted from Cassava Tubers. Sains Malaysiana , 46, 223–229. https://doi.org/10.17576/jsm-2017-4602-06. van Loon, L.J.C., Kruijshoop, M., Verhagen, H., Saris, W.H.M., Wagenmakers, A.J.M. 2000. Ingestion of Protein Hydrolysate and Amino Acid–Carbohydrate Mixtures Increases Postexercise Plasma Insulin Responses in Men. The Journal of Nutrition, 130, 2508–2513. https://doi.org/10.1093/jn/130.10.2508. Yadav, S., Mishra, B., Jha, R. 2019. Cassava (Manihot esculenta) root chips inclusion in the diets of broiler chickens: effects on growth performance, ileal histomorphology, and cecal volatile fatty acid production. Poultry Science, 98, 4008–4015. https://doi.org/10.3382/ps/pez143. Zhou, J., Wang, L., Zhou, J., Zeng, X., Qiao, S. 2021. Effects of using cassava as an amylopectin source in low protein diets on growth performance, nitrogen efficiency, and postprandial changes in plasma glucose and related hormones concentrations of growing pigs. Journal of Animal Science, 99 (12). https://doi.org/10.1093/jas/skab332. Cite Share Download PDF Status: Published Journal Publication published 24 Sep, 2024 Read the published version in Tropical Animal Health and Production → Version 1 posted Editorial decision: Major revision with re-assessment 30 Apr, 2024 Reviewers agreed at journal 11 Apr, 2024 Reviewers invited by journal 27 Mar, 2024 Editor assigned by journal 29 Feb, 2024 First submitted to journal 26 Feb, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3984805","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":284666677,"identity":"5d2f6085-1ea3-4c78-a06a-ae5105ec89d0","order_by":0,"name":"Yajin Yang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA80lEQVRIiWNgGAWjYPACNh4G9gYGhgoQ+wDRWniASs+QoAUIJBKI1GJw/Ozh1zw1fDLmks+fSRxsY5Dju5HA+LkAn5YzeWnWPMfYeCxn55iBtBhL3khglp6BT8uBHDNjHjY2HoPbOWy3P7YxJG64kcDGzINPy/k3QC3/gFpuHn92A2hLPWEtN3KMH/O2AbXcYDADaUkwIKRF8sYbM8a5fUAtZ3LMfxw4J2E488zDZml8WvjO5xh/ePPtmL3B8eOPDQ6U2cjzHU8++BmfFoUDDGxSPAzHYHwJIGZswKOBgUG+gYH54w+GGryKRsEoGAWjYIQDAC2OULRJZFloAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0009-0002-9471-2334","institution":"Southwest Forestry University","correspondingAuthor":true,"prefix":"","firstName":"Yajin","middleName":"","lastName":"Yang","suffix":""},{"id":284666678,"identity":"72c5b1ff-9a04-4d22-8a9b-38ac4cbbf3a9","order_by":1,"name":"Fuhong Lei","email":"","orcid":"","institution":"Yunnan Institute of Tropical Crops","correspondingAuthor":false,"prefix":"","firstName":"Fuhong","middleName":"","lastName":"Lei","suffix":""},{"id":284666679,"identity":"5c888c89-e816-44a0-babd-b3105d95f4ed","order_by":2,"name":"Zubing Zhang","email":"","orcid":"","institution":"Yunnan Institute of Tropical Crops","correspondingAuthor":false,"prefix":"","firstName":"Zubing","middleName":"","lastName":"Zhang","suffix":""},{"id":284666680,"identity":"39db36e5-9826-4060-9863-11a9d90812bc","order_by":3,"name":"Lily Liu","email":"","orcid":"","institution":"Southwest Forestry University","correspondingAuthor":false,"prefix":"","firstName":"Lily","middleName":"","lastName":"Liu","suffix":""},{"id":284666681,"identity":"4b7c4ad6-0bca-4897-97a9-c085aa9f8034","order_by":4,"name":"Qingqing Li","email":"","orcid":"","institution":"Southwest Forestry University","correspondingAuthor":false,"prefix":"","firstName":"Qingqing","middleName":"","lastName":"Li","suffix":""},{"id":284666682,"identity":"03bea0e0-6cdc-404f-b3b2-4be4b8740f49","order_by":5,"name":"Aiwei Guo","email":"","orcid":"https://orcid.org/0000-0002-9633-4050","institution":"Southwest Forestry University","correspondingAuthor":false,"prefix":"","firstName":"Aiwei","middleName":"","lastName":"Guo","suffix":""}],"badges":[],"createdAt":"2024-02-24 11:34:21","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3984805/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3984805/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s11250-024-04135-3","type":"published","date":"2024-09-24T15:58:15+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":53874741,"identity":"6e8c76d4-8085-4eb5-8780-58bd2e717d00","added_by":"auto","created_at":"2024-04-01 16:22:31","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":429714,"visible":true,"origin":"","legend":"\u003cp\u003eExperimental scheme\u003c/p\u003e\n\u003cp\u003eCT =Control; CRM15 = 15% CRM; CRM30 = 30% CRM; CRM45 = 45% CRM; n =35.\u003c/p\u003e","description":"","filename":"Fig.1.png","url":"https://assets-eu.researchsquare.com/files/rs-3984805/v1/037eff86b5f2a1a5d937c3d3.png"},{"id":53874743,"identity":"9234db0b-b95e-453b-9119-2ffa43323cc9","added_by":"auto","created_at":"2024-04-01 16:22:31","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":157142,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of CRM supplementation on nutrients apparent digestibility of broilers at 39-42 days of age\u003c/p\u003e\n\u003cp\u003eCT =Control; CRM15 = 15% CRM; CRM30 = 30% CRM; CRM45 = 45% CRM; (a-b) different letters mean significantly different groups (\u003cem\u003eP\u003c/em\u003e \u0026lt; 0.05), n =5.\u003c/p\u003e","description":"","filename":"Fig.2.png","url":"https://assets-eu.researchsquare.com/files/rs-3984805/v1/c93c51f04ef55d150cc8efc4.png"},{"id":53874742,"identity":"3f05f7e5-b78b-4cd2-98ac-f0756b230e09","added_by":"auto","created_at":"2024-04-01 16:22:31","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":159959,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of CRM supplementation on slaughter performance of broilers at 42 days of age\u003c/p\u003e\n\u003cp\u003eCT =Control; CRM15 = 15% CRM; CRM30 = 30% CRM; CRM45 = 45% CRM; (a-c) different letters mean significantly different groups (\u003cem\u003eP \u003c/em\u003e\u0026lt; 0.05), n =10.\u003c/p\u003e","description":"","filename":"Fig.3.png","url":"https://assets-eu.researchsquare.com/files/rs-3984805/v1/bf24920b6d2ff228e4d09d34.png"},{"id":65628187,"identity":"42c0b826-cd1f-41d7-86cb-bc6f6949c5dc","added_by":"auto","created_at":"2024-09-30 16:18:21","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1875889,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3984805/v1/06ed7084-5994-4049-a6b8-a62d0b627ceb.pdf"}],"financialInterests":"","formattedTitle":"Effects of cassava root meal on the growth performance, apparent nutrient digestibility, organ and intestinal indices, and slaughter performance of yellow-feathered broilers","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe global shortage of livestock feed resources is a common problem, with the animal feed industry being heavily reliant on corn, which provides 60\u0026ndash;70% of animal energy requirements (Ahiwe et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). With the current expansion of the livestock sector and continual world population growth, competition for food between humans and livestock has become an increasingly prominent issue, particularly in developing countries. Consequently, it is important to assess alternative energy sources that could be used to replace corn. Cassava (\u003cem\u003eManihot esculenta\u003c/em\u003e) is a widely consumed staple food grown in tropical and subtropical regions. Notably, it can be cultivated without fertilizer in dry, poor, and acidic soils that are unsuitable for growing corn and other crops (Pradyawong et al. \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Sixty-one percent of the global cassava crop is produced in Africa, with smaller proportions of 29% and 9% being grown in Asia and South America, respectively (FAO \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Compared with corn, cassava has the highest yield per unit land area of 25\u0026ndash;60 t /hm\u003csup\u003e2\u003c/sup\u003e\u003csub\u003e,\u003c/sub\u003e and cassava meal has lower production costs and a higher starch content (70\u0026ndash;80%), also has potential to partially replace corn in poultry feed (Garcia and Dale \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e1999\u003c/span\u003e, Rolland-Sabate et al. 2012, Chang'a et al. 2020). To date, however, the use of cassava in conventional feeds has been limited by certain factors. notably the low contents of essential amino acids and high levels of cyanogenic glycosides (Tiwari and Jha \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). In particular, the lack of methionine and lysine in cassava necessitates a close consideration of the nutritional profiles of feed formulations (Oke \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e1978\u003c/span\u003e). Nevertheless, Adeyemi et al. (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2008\u003c/span\u003e) overcames the problem of low amino acid contents by supplementing broiler diets with synthetic amino acids, whereas the cyanogenic glycoside contents in cassava can be reduced by applying appropriate processing methods such as soaking, sun drying, boiling, and fermentation (Omede et al. \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), among which, sun drying has been found to be more effective than oven-drying in a number of studies (Tewe, 2004, Panigrahi S et al. \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e1992\u003c/span\u003e, Gomez et al. \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e1984\u003c/span\u003e). As an energy source in poultry feed, numerous studies have assessed the effects of replacing corn meal with cassava or pretreated cassava, with the aim of optimizing the supply of glucose and enhancing absorption efficiency (Chukwukaelo, 2018, Alade et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2020\u003c/span\u003e, Okrathok et al. 2022). The amylopectin content in cassava is digested and absorbed more rapidly in the form of glucose than is amylose, which can be attributed to the facts that amylopectin readily gels and has a larger surface area for digestive enzyme activity (Martens \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2019\u003c/span\u003e, Zhou et al. \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Consequently, the incorporation of cassava in livestock diets can contribute to optimizing glucose supply and enhancing absorption efficiency. Notably, however, the benefits of supplementing poultry diets with cassava tend to be variety dependent, and thus nutrient determinations and feeding studies are needed to establish the appropriate proportions of dietary supplementation. In this regard, Picoli et al. (\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2014\u003c/span\u003e) revealed that slow-growing broiler diets containing 10% cassava had no negative effects on carcass yield or abdominal fat deposition, whereas da Silva et al. (\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2019\u003c/span\u003e) has reported that the inclusion of dry residues of cassava in broiler diets affected breast yield, with the maximum addition estimated at 4.06%. Although the aforementioned studies have shown that the inclusion of cassava concentrate in broiler diets has potential benefits when nutrients are correctly balanced, the effects can differ depending on the appropriate proportions of different sources of cassava, broiler species, and treatment methods. To date, however, there have been no systematic studies that have examined the effects of replacing corn with cassava on the production performance, nutrient digestibility, and intestinal development of broilers. Accordingly, in this study, we aimed to investigate the effects of cassava root meal (CRM) as a substitute for maize on the growth performance, apparent digestibility of nutrients, organ and gastrointestinal tract indices, and slaughter performance of broilers from 1 to 42 days of age. Our findings will provide useful information for guiding the use of cassava as an alternative energy source, and thereby go some way to alleviating the competing requirements of humans and livestock for food.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eAnimals and housing\u003c/h2\u003e \u003cp\u003eA total of 140 one-day-old male yellow-feathered broilers were acquired from a commercial hatchery in Kunming, China. The birds were randomly assigned to four treatment groups, each with five replicates, and seven birds per replicate. All experimental procedures received approval from the Academic Committee of Southwest Forestry University. Throughout the initial week of the 42-day trial, the room temperature was kept within the range of 32\u0026ndash;35\u0026deg;C using air conditioning. Subsequently, it was gradually reduced to 24\u0026deg;C by day 21 and maintained at that level for the remainder of the trial. The chicks were raised in cages under constant illumination throughout the study period, with ad libitum access to both food and water.\u003c/p\u003e \u003cp\u003eC\u003cb\u003eassava root meal preparation and broiler diets\u003c/b\u003e\u003c/p\u003e \u003cp\u003eThe cassava SC9 variety used in this study is a widely cultivated high-yielding low-cyanogenic glycoside variety bred in Yunnan Province. To prepare the CRM, the roots were initially washed and then sliced, sun-dried, and crushed. The chemical composition of the CRM, determined using AOAC-\u003c/p\u003e \u003cp\u003erecommended methods (AOAC \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2012\u003c/span\u003e), was as follows: starch, 75.12%; crude protein, 4.45%; ether\u003c/p\u003e \u003cp\u003eextract, 0.95%; crude fiber, 4.63%; ash, 4.14%; nitrogen-free extract, 85.83%; calcium, 0.22%;\u003c/p\u003e \u003cp\u003ephosphorus, 0.16%; cyanogenic glycoside, 0.9 mg/kg; tannin, 470 mg/kg, and L (+)-ascorbic acid, 28.8 mg/100 g. From day one, the birds were subjected to one of the following four dietary treatments: a basal diet as the control (CT), and three diets in which corn was replaced with 15% (CRM15), 30% (CRM30), or 45% (CRM45) cassava root meal (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The diets were formulated in accordance with the recommendations of the National Research Council (NRC \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e1994\u003c/span\u003e) and the nutrient requirements of yellow-feathered broilers (MAC 2017), as shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eIngredient composition and calculated nutrient levels of the experimental diets\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eItems\u003csup\u003e1\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"4\" nameend=\"c5\" namest=\"c2\"\u003e \u003cp\u003eTreatments\u003csup\u003e1\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCT\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCRM15\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCRM30\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCRM45\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIngredients (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"4\" nameend=\"c5\" namest=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCorn\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e60.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e45.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e30.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e15.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCassava root meal (ME, 14.47 MJ/kg)\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e30.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e45.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSoybean meal (43% CP)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e26.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e26.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e25.79\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFish meal (65% CP)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8.70\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCorn protein meal (50% CP)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSoybean oil\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eL\u003c/em\u003e-Lysine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eDL\u003c/em\u003e-Metonine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.25\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLimestone\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDicalcium phosphate\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.40\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSodium chloride\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVitamin and mineral premix\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCholine chloride (50%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.26\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e100.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e100.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e100.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCalculated nutrient content\u003c/b\u003e\u003csup\u003e\u003cb\u003e2\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c5\" namest=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eME (MJ/kg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12.45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e12.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e12.49\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCrude protein (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e21.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e21.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e21.19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e21.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEther extract (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.84\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.97\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCrude fibre (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.64\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLysine (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.20\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMethionine\u0026thinsp;+\u0026thinsp;Cys (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.88\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCalcium (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNonphytate phosphorus (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.49\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.47\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCyanogenic glycoside (mg/kg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.41\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e1 CT\u0026thinsp;=\u0026thinsp;Control (0% CRM supplement); CRM 15\u0026thinsp;=\u0026thinsp;15% CRM supplement; CRM 30\u0026thinsp;=\u0026thinsp;30% CRM supplement; CRM 45\u0026thinsp;=\u0026thinsp;45% CRM supplement.\u003c/p\u003e \u003cp\u003e2 Calculated based on analysis of raw materials (Dale N \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e1996\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e3 The premix is supplied with the following per kilogram of diet: Vitamin A, 8000; IU; Vitamin D3, 1000 IU; Vitamin E, 20 mg; Vitamin K3, 0.5 mg; Vitamin B1, 2 mg; Vitamin B2, 8 mg; Vitamin B6, 3.5 mg; niacin, 35 mg; biotin, 0.18 mg; Folic acid, 0.55 mg; pantothenic acid, 10 mg; Manganese, 100 mg; Zinc, 80 mg; Iron, 80 mg; Copper, 9 mg; Iodine, 0.35 mg; Selenium,0.15 mg.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eGrowth performance and body measurements\u003c/h2\u003e \u003cp\u003eThroughout the study period, the body weight (BW) and feed intake (FI) of broilers were measured at weekly intervals. Feed intake was calculated as the difference between the feed offered and that remaining unconsumed. The feed conversion ratio (FCR) was computed as the ratio of feed consumed to weight gain. At 21 and 42 days of age, body measurements (keel length, breast depth, breast width, hip width, shank length, and shank circumference) of each bird were obtained according to the methods recommended by the Chinese National Poultry Breeding Committee (CNPBC 1984).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eApparent digestibility of nutrients\u003c/h2\u003e \u003cp\u003eThe apparent digestibility of nutrients was determined using a total excreta collection procedure (Khalil et al. \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). The feed intake and total excreta output for each replicate cage were recorded over the final four consecutive days of the study. Excreta from each cage were collected and extraneous material, such as feathers, was removed. The excreta was subsequently sprayed with hydrochloric acid diluent (V/V, 1:3) and dried at 60\u0026deg;C, after which it was ground and stored for further analysis. To assess the apparent digestibility of broilers, sample of the diets and excreta were analyzed for determinations of dry matter, crude protein, ether extract, and crude ash using standard methods (AOAC \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2012\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eOrgan and gastrointestinal tract indices and slaughter performance\u003c/h2\u003e \u003cp\u003eAt 42 days of age, two birds from each replicate (40 birds in total) with representative mean body weights were selected for slaughter. Prior to slaughter, the birds were fasted overnight, feathers and internal organs were removed to evaluate slaughter performance using methods recommended by the Chinese National Poultry Breeding Committee (CNPBC 1984). The following organs and intestinal segments were separated and weighed, with weights being expressed as a ratio to the living BW: liver, spleen, thymus, bursa, heart, pancreas, proventriculus, gizzard, duodenum, jejunum, ileum, and rectum. In addition, the weights of the carcass, semi-evisceration, evisceration, breast muscle, and thigh muscle were recorded and expressed as a ratio to the living BW.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eThe statistical model included the level of CRM supplementation as a treatment effect. Data were analyzed by one-way ANOVA analysis using the General linear model program of SPSS 21.0. The significance of differences between groups determined using Tukey\u0026rsquo;s test. All statistical analyses were declared significantly different at a \u003cem\u003eP\u003c/em\u003e-value of less than 0.05.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eGrowth performance and body measurement indices\u003c/h2\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows the effects of CRM supplementation on the growth performance of broilers. From 1 to 21 days of age, the body weight (BW), average daily gain (ADG), and average daily feed intake (ADFI) of broilers in the CRM groups were found to be significantly lower than those in the CT (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). From 22 to 42 days of age, the BW of CT birds was significantly higher than that in the CRM groups (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05) whereas we detected no significant differences between the CRM15 and CT with respect to ADG, ADFI, and FCR. Throughout the experimental period (1\u0026ndash;42 days of age), we recorded higher FCR values among birds in the CRM30 and CRM45 compared with those in the CT and CRM15. As body measurements, we assessed six traits, all of which had declined significantly with an increase in supplemental CRM compared with those in control birds when measured at 21 days of age (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). At 42 days of age, we detected no significant differences between the CT and CRM15 birds with respect to keel length, breast width, hip width, and shank length, whereas the values for these traits in CRM30 and CRM45 birds were significantly lower than those in the CT (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eEffect of dietary CRM supplementation on growth performance of broilers\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eItems\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eDays of age\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c6\" namest=\"c3\"\u003e \u003cp\u003eTreatments\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eSEM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cem\u003eP-\u003c/em\u003eValue\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCRM15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCRM30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eCRM45\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eBW (g)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e39.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e39.31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e38.69\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e39.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.569\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e486.79\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e439.12\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e421.37\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e379.29\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e9.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1371.74\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1282.81\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1212.80\u003csup\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1094.68\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e26.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eADG (g/d)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1\u0026ndash;21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25.16\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e22.29\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e20.78\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e18.18\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.66\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22\u0026ndash;42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e42.14\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e40.18\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e37.69\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e34.07\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1\u0026ndash;42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e35.35\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e33.02\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e30.62\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e27.71\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.76\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eADFI (g/d)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1\u0026ndash;21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e45.50\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e41.05\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e40.91\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e38.05\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22\u0026ndash;42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e91.81\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e88.43\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e87.27\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e82.84\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.008\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1\u0026ndash;42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e68.66\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e64.16\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e64.67\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e60.44\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eFCR\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1\u0026ndash;21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.81\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.84\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.98\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2.11\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.030\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22\u0026ndash;42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.316\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1\u0026ndash;42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.94\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.95\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.09\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2.19\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.019\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eCT\u0026thinsp;=\u0026thinsp;Control (0% CRM supplement); CRM15\u0026thinsp;=\u0026thinsp;15% CRM; CRM30\u0026thinsp;=\u0026thinsp;30% CRM; CRM45\u0026thinsp;=\u0026thinsp;45% CRM.\u003c/p\u003e \u003cp\u003eMeans with different superscript letters within a row are significantly different (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). SEM standard error of means.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eEffect of dietary CRM supplementation on body measurements of broilers\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eItems\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBody measurements\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCT\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCRM15\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCRM30\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eCRM45\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eSEM\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u003cem\u003eP-\u003c/em\u003eValue\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"5\" rowspan=\"6\"\u003e \u003cp\u003e21 days of age\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eKeel length (cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8.00\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.58\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5.80\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e5.36\u003csup\u003ed\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBreast depth (cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6.88\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6.26\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5.56\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4.40\u003csup\u003ed\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBreast width (cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6.16\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5.18\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4.72\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4.12\u003csup\u003ed\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHip width (cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6.06\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5.56\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4.90\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4.43\u003csup\u003ed\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eShank length (cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6.76\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6.07\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6.06\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e5.40\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eShank circumference (cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.47\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.30\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3.07\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3.09\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"5\" rowspan=\"6\"\u003e \u003cp\u003e42 days of age\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eKeel length (cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12.20\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11.25\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e9.14\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e8.71\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBreast depth (cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8.53\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e8.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.351\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBreast width (cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9.62\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9.71\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8.55\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e7.27\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHip width (cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10.07\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9.61\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8.12\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e8.42\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eShank length (cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10.00\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10.07\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8.03\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e8.53\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eShank circumference (cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.49\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4.65\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4.22\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4.29\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.008\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eCT\u0026thinsp;=\u0026thinsp;Control (0% CRM supplement); CRM15\u0026thinsp;=\u0026thinsp;15% CRM; CRM30\u0026thinsp;=\u0026thinsp;30% CRM; CRM45\u0026thinsp;=\u0026thinsp;45% CRM.\u003c/p\u003e \u003cp\u003eMeans with different superscript letters within a row are significantly different (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). SEM standard error of means.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eApparent digestibility of nutrients\u003c/h2\u003e \u003cp\u003eThe results obtained for the apparent digestibility of nutrients are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. From 39 to 42 days of age, we detected no significant differences between the CRM15 and CT birds regarding the apparent digestibility of dry matter, crude protein, ether extract, or crude ash (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05), whereas in response to dietary supplementation with 30% and 45% CRM, there was a significant reduction in the apparent digestibility of dry matter, crude protein, and ether extract (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Contrastingly, we detected no significant differences among treatments with respect to the digestibility of crude ash (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eOrgan and gastrointestinal tract indices\u003c/h2\u003e \u003cp\u003eAs shown in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, among the assessed organ indices of 42-day-old broilers, the heart index of CRM30 birds was significantly lower than that of birds in the other three groups (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05), whereas the thymus indices of the CRM30 and CRM45 group birds was slightly higher than that of birds in the other groups. Otherwise, we detected no appreciable differences among groups with respect the other organ indices (liver, spleen, bursa, and pancreas) (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Among the assessed gastrointestinal tract indices, those for the jejunum and ileum in the CRM35 and CRM45 birds were significantly lower than those in the CT birds (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05), whereas there was little difference between the CRM15 and CT groups with respect to jejunum index (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). Apart from these difference, we detected no significant differences among the groups with respect to other gastrointestinal tract indices (i.e., proventriculus, gizzard, duodenum, and cecum (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eEffect of dietary CRM supplementation on organ index of broilers at 42 days of age\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eItems\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCT\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCRM15\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCRM30\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCRM45\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eSEM\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eP-\u003c/em\u003eValue\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLiver, g/kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e20.97\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e20.99\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e19.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e21.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.557\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpleen, g/kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.718\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eThymus, g/kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5.73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6.86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.187\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBursa, g/kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.111\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHeart, g/kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7.08\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6.74\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5.43\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6.07\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.009\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePancreas, g/kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.217\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eCT\u0026thinsp;=\u0026thinsp;Control (0% CRM supplement); CRM15\u0026thinsp;=\u0026thinsp;15% CRM; CRM30\u0026thinsp;=\u0026thinsp;30% CRM; CRM45\u0026thinsp;=\u0026thinsp;45% CRM.\u003c/p\u003e \u003cp\u003eMeans with different superscript letters within a row are significantly different (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). SEM standard error of means.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eEffect of dietary CRM supplementation on gastrointestinal tract index of broilers at 42 days of age\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eItems\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCT\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCRM15\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCRM30\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCRM45\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eSEM\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eP-\u003c/em\u003eValue\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eProventriculus, g/kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.711\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGizzard, g/kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e20.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e16.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e17.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e16.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.204\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDuodenum, g/kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7.19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6.76\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.397\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eJejunum, g/kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10.01\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9.31\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9.04\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8.84\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.019\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIleum, g/kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10.41\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9.39\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9.28\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8.72\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.016\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCecum, g/kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5.73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.616\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRectum, g/kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.140\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eCT\u0026thinsp;=\u0026thinsp;Control (0% CRM supplement); CRM15\u0026thinsp;=\u0026thinsp;15% CRM; CRM30\u0026thinsp;=\u0026thinsp;30% CRM; CRM45\u0026thinsp;=\u0026thinsp;45% CRM.\u003c/p\u003e \u003cp\u003eMeans with different superscript letters within a row are significantly different (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). SEM standard error of means.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eSlaughter performance\u003c/h2\u003e \u003cp\u003eResults for the slaughter performance of broilers at 42 days are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. These reveal significant reductions in the slaughter indices (slaughter ratio, breast muscle ratio, and thigh muscle ratio) of birds fed CRM diets compared with the CT birds (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). However, we detected no significant differences between the CRM15 and CT groups in terms of semi-evisceration and evisceration ratios, although compared with the control group, cassava supplementation was associated with significant reductions in the proportions of breast and thigh muscles at 42 days of age ( \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e "},{"header":"Discussion","content":"\u003cp\u003eCassava, characterized by a high productivity per unit area, is one of the three major tuber crops cultivated worldwide, and is considered an effective source of energy for livestock production (Rolland-Sabat\u0026eacute; et al. \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2012\u003c/span\u003e, Li et al. \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). However, the widespread use of cassava in livestock feed has been limited on account of its low levels of certain essential amino acids and high hydrocyanic acid content (Tiwari and Jha \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). However, Falade and Akingbala (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2010\u003c/span\u003e) have confirmed that adequate drying can reduce the concentrations of hydrocyanic acid in cassava to acceptable levels. In this study, we used the SC9 variety of cassava, which has been established to be a low cyanogenic glycoside (0.9 mg/kg) variety. The levels of cyanogenic glycoside in the feed formulae calculated in this study ranged from 0.14 to 0.41 mg/kg, which meet the requirements for cyanogenic glycoside contents outlined in the feed hygiene standards of China (\u0026lt;\u0026thinsp;100 mg/kg) (MAC 2017).\u003c/p\u003e \u003cp\u003eThe performance of broilers fed cassava diets varied depending on the level of cassava content in their diet. Gomez et al. (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e1984\u003c/span\u003e) have reported that supplementation of broiler diets with 30% CRM had no appreciable adverse effects on the body weights of birds. Similarly, weight gain was not affected in chickens fed 10% cassava leaf meal (Bakare et al. 2020), 20% cassava peel meal (Oyebimpeet al. \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2006\u003c/span\u003e), 60% composite cassava meal (Ukachukwu \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). Contrastingly, in the present study, we detected significant reductions in the BW, ADG, and ADFI of broilers during the initial period (1\u0026ndash;21 day) of feeding on CRM-supplemented diets. Compared to corn with a crude protein level of 8%-9% (Koehler and Wieser \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2013\u003c/span\u003e), dried cassava is characterized by low protein contents (4.45%) and high levels of fiber (4.63%), which would limit nutrient digestion in the small intestines of poultry (Aro et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2008\u003c/span\u003e, Rapha\u0026euml;l et al. \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). These observations reflect the relatively the poor ability of chicks to digest cassava early in life, as at this stage their digestive tract have yet fully develop.\u003c/p\u003e \u003cp\u003eHowever, during the latter stages of the trial (22\u0026ndash;42 days), these detrimental effects became increasingly less apparent in the CRM15 broilers. Similarly, Yadav also observed a linear reduction in the BW of chicks fed diets supplemented with 37.5% and 50% cassava during the starter periods, whereas these high levels of cassava had little effect on ADG and ADFI during the latter phase of growth (Yadav et al. \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Throughout the 42 d feeding period in this study, we found that the FCR of birds in the CRM15 was similar to that of CT birds, although supplementation with CRM had an negative influence on the weight gain of broilers. A well-developed gut is essential for the efficient utilization of cassava, as high levels of starch and fiber evades digestion in the small intestine and passes to the large intestine, wherein it is fermented by the gut microbiota (Oladunmoye et al. \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2014\u003c/span\u003e, Jha and Berrocoso \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). These high fiber and starch contents of cassava may play a prebiotic role in the fully developed hindgut segment. However, birds in the CRM30 and CRM45 were characterized by lower values for BW and body measurements, which would accordingly lead to longer rearing times and higher feed consumption. Previous studies have also found that supplementation with higher levels of CRM in broilers delayed weight gain (Ochetim 1991, Ru et al. \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). Similar to this study, dietary CRM supplementation was observed to retard the growth of broilers during the early stage (1\u0026ndash;21 days) of the feeding trial, whereas the body measurements of CRM15 birds were not significantly different from those of CT birds during the latter stage of the trial (22\u0026ndash;42 days), thereby indicating that the growth of CRM15 broilers substantially improved with a prolongation of the period during which they fed on a CRM-supplemented diet. Despite the fact that body measurements closely reflect poultry growth, development, and flock uniformity, particularly in intensive poultry production systems, the effects of CRM on the body measurements of broilers has rarely been reported (He et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). In the present study, we established that whereas supplementing broiler diets with CRM15 had no appreciable adverse effects on the growth or development of broilers, the use of high levels of CRM (30% and 45%) had negative effects on broiler growth and body measurements.\u003c/p\u003e \u003cp\u003eStudy have shown that apparent digestibility is reduced when corn is substituted with more than 30% cassava, and that feeding dried potato pulp at 25% also reduces nutrients apparent digestibility and retention (Khempaka et al. \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). In the present study, we found that replacing corn with 30% and 45% cassava contributed to significant reductions in the apparent digestibility of dry matter, crude protein, and ether extract in broilers. However, substitution ratio of 15% showed no significant difference compared to the CT broilers. This effect could be attributable to the fact that cassava is rich in non-starch polysaccharides (NSP), which are mostly insoluble. In this regard, the concentration of water-soluble NSP in cassava root was lower (0.078% ~ 1.64%) than that in maize (8.4%) and soybean (9.8%) (Meng and Slominski \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2005\u003c/span\u003e, Chauynarong et al. 2015, Uthumporn et al. \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Insoluble NSP reduces the efficient digestion of nutrients by interfering with the action of amylase and protease (Morgan et al. 2016). Nevertheless, these SNP in cassava can serve as a substrate for microbial fermentation, which influences the production of short-chain fatty acids (Canfora and Blaak \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2017\u003c/span\u003e), which, along with glucose, are essential nutrients for metabolic conversions in the body. The main amino acids found in cassava root are glutamine, alanine, and asparagine, while the content of methionine and cysteine, which are key essential amino acids in poultry diet, is relatively low (Morgan et al. 2016). The low protein content of cassava root makes it a significant disadvantage for its use in poultry feed. Furthermore, the co-ingestion of glucose and amino acids has been shown to have a synergistic effect in potentiating insulin secretion and subsequently stimulating muscle protein synthesis (Van Loon et al. \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). Accordingly, supplementing feed with amino acids or subjecting cassava to fermentation are considered effective approaches to enhancing the nutritional value of supplemental cassava, as has been confirmed by some studies (Aladi et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2021\u003c/span\u003e, Chang'a et al. 2020, Diarra and Anand \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eDietary constituents can influence the structure of the digestive tract and the passage of digesta through the gastrointestinal tract. For example, the intake of roughage has the effect of promoting increased muscle activity in the gizzard, thereby contributing to a gain in weight, and maximizing the grinding ability of the gastrointestinal tract (Jacobs and Parsons, 2013). Indeed, it has been demonstrated that the gizzards of broilers fed coarse diets were 15% heavier than those of birds fed fine diets. Furthermore, high-protein diets have been found to reduce intestinal villus height/crypt depth and butyric acid production. Guo et al. (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) has also reported that the digestive tract weight indices of the gizzard and rectum increased in birds fed a diet supplemented with pine needle powder. Similarly, svihus (\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2011\u003c/span\u003e) found that consumption of feed containing structural components, such as hulls, wood shavings, or large cereal particles, can contribute to a rapid and significant enlargement in the size of the gizzard. In the present study, we found that supplementing diets with CRM had no significant effects on the indices of the proventriculus and gizzard of broilers at 42 days of age, although contributed to reduction in the indices of the jejunum and ileum, which could plausibly be attributed to the crude fiber content of the cassava (4.63%) used to supplement the diets, which was not sufficient to alter the weight of the gastrointestinal tract.\u003c/p\u003e \u003cp\u003eSimilar to the findings of previous studies that have reported that supplementing the diet of slow-growing broilers with 10% cassava had no significant effects on carcass or growth performance (da Silva et al. \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2019\u003c/span\u003e, Almeida et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), we found that when broilers were fed a diet in which corn was replaced with 15% cassava, there was no significant differences in the rates of semi-evisceration and evisceration in the broilers compared with the controls, and no significant difference in the organ indices of groups. However, differences in the other slaughter indices were mainly reflected in the proportions of breast and thigh muscles. It can thus be speculated that the observed differences in carcass yield may be associated with the balance of amino acids in the diet. It has, for example, been established that the amounts and proportions of methionine and lysine are directly linked to carcass and slaughter yields, particularly with respect to muscle tissue, which accounts for approximately 50% of total carcass protein. Similarly, the findings of previous studies have indicated that substitution with 10\u0026ndash;16% cassava had no appreciable effects on the muscle mass of poultry, whereas substituting maize with 40% CRM had the effect of reducing breast yield (Omede et al. \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2018\u003c/span\u003e, Khempaka et al. \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). Given that rapid protein deposition is dependent on efficient nutrient conversion, low-protein cassava supplementation may be more appropriate for the growth of slow-growing broilers. Further studies are required to examine the synergistic promotion effect of the proportional composition of nutrient.\u003c/p\u003e \u003cp\u003eIn this study, we found that replacing corn in the diets of yellow-feather broilers with 15% cassava root meal did not significantly influence the production performance, rate of nutrient digestibility, slaughter performance, or gastrointestinal tract indices of broilers chicks compared with control birds. In addition, the substitution is best done at a later stage. In contrast, high levels of dietary cassava can inhibit the production performance, nutrient digestibility, and slaughter performance of these broilers. Accordingly, our findings indicate that when supplemented at appropriate levels, cassava root meal, as an alternative high-yield inexpensive energy feed source, may be feasible and effective in broiler production.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eWe also would like to thank Editage (www.editage.cn) for English language editing. \u0026nbsp;\u003c/p\u003e\u003cp\u003e \u003ch2\u003eEthics approval\u003c/h2\u003e \u003cp\u003eThis study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the Ethics Committee of Southwest Forestry University.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent to participate\u003c/strong\u003e \u003cp\u003eNot applicable.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent for publication\u003c/strong\u003e \u003cp\u003eNot applicable.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eCompeting Interests\u003c/strong\u003e \u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThis work was supported by [Science Research Foundation Project of Yunnan Education Department under Grant [number 2022J0504]; [National Natural Science Foundation of China under grant number 31860650, 31460609]; [National Cassava Industry Technology System Xishuangbanna Comprehensive Experimental Station Project under Grant CARS-11-YNLHHQ]; The Key Laboratory of Forest Biotechnology in Yunnan, Southwest Forestry University; The Scientific and Technological Innovation Team Construction Project for Protection and Utilization of Under-forest Biological Resources in Universities of Yunnan Province.\u003c/p\u003e\u003ch2\u003eAuthor Contributions\u003c/h2\u003e \u003cp\u003eAll authors participated in the study conception and design. Material preparation, data collection and analysis were performed by all the authors. The first draft of the manuscript was written by Yajin Yang and Aiwei Guo edited the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\u003ch2\u003eData availability\u003c/h2\u003e \u003cp\u003eData will be made available on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAdeyemi, O.A., Eruvbetine, D., Oguntona, T., Dipeolu, M.A., Agunbiade, J.A. 2008. Feeding broiler chicken with diets containing whole cassava root meal fermented with rumen filtrate. Archivos de Zootecnia. 57(218), 247-258.\u003c/li\u003e\n\u003cli\u003eAhiwe, E.U., Omede, A.A., Abdallh, M. B., Iji, P.A. 2018. Managing Dietary Energy Intake by Broiler Chickens to Reduce Production Costs and Improve Product Quality. 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Poultry Science, 98, 4008\u0026ndash;4015. https://doi.org/10.3382/ps/pez143.\u003c/li\u003e\n\u003cli\u003eZhou, J., Wang, L., Zhou, J., Zeng, X., Qiao, S. 2021. Effects of using cassava as an amylopectin source in low protein diets on growth performance, nitrogen efficiency, and postprandial changes in plasma glucose and related hormones concentrations of growing pigs. Journal of Animal Science,\u003cem\u003e \u003c/em\u003e99 (12). https://doi.org/10.1093/jas/skab332.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"tropical-animal-health-and-production","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"trop","sideBox":"Learn more about [Tropical Animal Health and Production](https://www.springer.com/journal/11250)","snPcode":"11250","submissionUrl":"https://submission.nature.com/new-submission/11250/3","title":"Tropical Animal Health and Production","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"cassava root meal, growth performance, apparent digestibility, organ index, broiler","lastPublishedDoi":"10.21203/rs.3.rs-3984805/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3984805/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eTo investigate the effects of cassava root meal (CRM) on the growth performance, apparent digestibility, and organ and intestinal indices of broilers. A total of 140 one-day-old chicks were randomly assigned to one of four dietary treatment groups [control diet (CT), 15% CRM (CRM15), 30% CRM (CRM30), and 45% CRM (CRM45)] with five replicates of seven birds per replicate. The Results showed that the body weight of broilers in the CRM groups was significantly lower than that in the CT group at 21 and 42 days of age, and the average daily gain and average daily feed intake in the CRM group were significantly lower than those in the CT group from 1 to 21 days of age. However, from days 22 to 42, there were no significant differences between CRM15 and CT birds regarding average daily gain and average daily feed intake. but there was no difference in feed conversion rate between the CRM15 and CT groups. At 42 days of age, there were no significant differences between CRM15 and CT birds in in body measurements, the slaughter performance and semi-evisceration ratio. The addition of CRM reduced the proportion of breast and thigh muscles during the feeding period, although we detected no significant difference between CRM15 and CT regarding the apparent digestibility of nutrients. Collectively, our findings indicate that 15% cassava was the optimal proportion for supplementing diets for broiler production.\u003c/p\u003e","manuscriptTitle":"Effects of cassava root meal on the growth performance, apparent nutrient digestibility, organ and intestinal indices, and slaughter performance of yellow-feathered broilers","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-04-01 16:22:26","doi":"10.21203/rs.3.rs-3984805/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Major revision with re-assessment","date":"2024-04-30T07:19:45+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"","date":"2024-04-11T20:27:08+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-03-27T18:04:44+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-02-29T06:42:15+00:00","index":"","fulltext":""},{"type":"submitted","content":"Tropical Animal Health and Production","date":"2024-02-27T03:46:09+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"tropical-animal-health-and-production","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"trop","sideBox":"Learn more about [Tropical Animal Health and Production](https://www.springer.com/journal/11250)","snPcode":"11250","submissionUrl":"https://submission.nature.com/new-submission/11250/3","title":"Tropical Animal Health and Production","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"8345fa79-f66f-409e-8e87-42a7879d4121","owner":[],"postedDate":"April 1st, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-09-30T16:11:52+00:00","versionOfRecord":{"articleIdentity":"rs-3984805","link":"https://doi.org/10.1007/s11250-024-04135-3","journal":{"identity":"tropical-animal-health-and-production","isVorOnly":false,"title":"Tropical Animal Health and Production"},"publishedOn":"2024-09-24 15:58:15","publishedOnDateReadable":"September 24th, 2024"},"versionCreatedAt":"2024-04-01 16:22:26","video":"","vorDoi":"10.1007/s11250-024-04135-3","vorDoiUrl":"https://doi.org/10.1007/s11250-024-04135-3","workflowStages":[]},"version":"v1","identity":"rs-3984805","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3984805","identity":"rs-3984805","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}