Evaluating Lactation Persistency, Lactation Curve Parameters, and Dairy Efficiency: The Role of Parity, Calving Season, and Days Open in Holstein-Friesian Cows

Evaluating Lactation Persistency, Lactation Curve Parameters, and Dairy Efficiency: The Role of Parity, Calving Season, and Days Open in Holstein-Friesian Cows | 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 Evaluating Lactation Persistency, Lactation Curve Parameters, and Dairy Efficiency: The Role of Parity, Calving Season, and Days Open in Holstein-Friesian Cows Serdar Güler, Ali Akmaz This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6440916/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract This study investigates the influence of parity, calving season (CS), and days open (DO) on milk yield and lactation traits in Holstein-Friesian cows. A total of 5171 test-day milk yield records collected from 307 cows were analyzed using the Wood equation with non-linear regression. The findings reveal significant effects of these factors on 305-day milk yield (305-dMY), lactation curve parameters (a, b, c), peak milk yield (Y max ), time to peak yield (T max ), and lactation persistency (S). Multiparous cows and those calving in winter produced notably higher 305-dMY compared to primiparous cows and cows calving in other seasons. While primiparous cows demonstrated lower initial and peak milk yields and took longer to reach peak yield, they exhibited stronger lactation persistency. Seasonal variations also impacted lactation performance, with autumn and winter calving associated with higher peak milk yield (Y max ) and improved persistency. Days open (DO) played a crucial role in shaping lactation traits, as cows with 151–180 days open achieved the highest peak yield and lactation persistency, while those with ≤ 60 DO exhibited significantly lower persistency and milk yield across all traits. These findings highlight the importance of integrating parity, calving timing, and DO management into strategic herd management practices. Optimizing these factors can substantially improve milk production, lactation performance, and overall farm efficiency, offering actionable insights for sustainable dairy farming. This study reinforces the need for evidence-based approaches to enhance productivity and support long-term dairy industry growth. Calving season Days open Lactation curve Persistency of lactation Milk production Figures Figure 1 Figure 2 Figure 3 Introduction Lactation is a complex process that consists milk synthesis, secretion and some of the mammary gland development stage (Mukherjee et al. 2023 ). Level of the milk production has an economic impact on dairy farms. One of the most important indicator of the level of milk yield is lactation persistency (Güler and Akmaz 2020 ). Lactation persistency is defined as continuity of the milk yield after the lactation peak and shape of the lactation curve determines the persistency (Güler and Akmaz 2020 ; Angeles-Hernandez et al. 2021 ). A standard lactation curve consists of three phases, initial milk yield, increasing slope and decreasing slope until the dry of (Güler and Akmaz 2020 ; Angeles-Hernandez et al. 2021 ; Sanad and Gharib 2022 ). To make critical decisions in dairy farms, estimating shape of the lactation curve is crucial because of the fact that lactation persistency is an economical trait impacts feed costs, fertility and health (Dekkers et al. 1998 ; Piccardi et al. 2017 ; Oliveira et al. 2024 ). Lactation curve and its traits, thus milk yield affected by both genetic and environmental factors such as parity, season of calving, season of month, calving year, calving age and dry period length (Güler and Akmaz 2020 ). In a lot of cattle breeds including Holstein-Friesian several non-linear functions were widely used by the researchers to determine the lactation curve parameters and the lactation persistency for decades (Tekerli et al. 2000b ; Kopec et al. 2021 ; Otwinowska-Mindur et al. 2021 ; Chiba et al. 2022 ; Hernández-Zamudio et al. 2022 ). Although a lot of nonlinear functions were developed to determine the lactation curve traits and lactation persistency since beginning first quarter of the 20th century, a gamma function called Wood model (Wood 1967 ) were mostly used still in nowadays. The effect of parity and season of calving (Tankal and Tüzemen 2022 ) and days open (Abd-El Hamed and Kamel 2021 ) on 305-dMY, also determined to be significant in some studies. In previous studies the effect of parity on parameter a, b and c (Wood 1969 ; Wood 1970 ; Rowlands et al. 1982 ; Darej et al. 2012 ), lactation persistency (Tekerli et al. 2000b ; Rekik et al. 2003 ; Albarrán-Portillo and Pollott 2011 ; Atashi et al. 2013 ; Torshizi et al. 2019 ; Jiang et al. 2020 ; Lee et al. 2020 ), T max and Y max (Tekerli et al. 2000b ; Rekik et al. 2003 ; Jiang et al. 2020 ; Masía et al. 2020 ) were studied. Also, significant effect of calving season on parameter a (Bouallegue et al. 2014 ), parameter b and c (Atashi et al. 2009 ), lactation persistency (Kopec et al. 2013 ; Khalifa et al. 2018 ), T max and Y max (Sanad and Gharib 2022 ) were reported. In addition of days open on parameter b and c (Tekerli et al. 2000b ), lactation persistency (Ruban et al. 2022 ), T max (Lopez-Villalobos et al. 2005 ) and Y max (Al-Atiyat et al. 1999 ) were determined. Several factors effect on 305-dMY such as parity, calving season, calving month, calving year, age at first calving, calving interval, days open, dry period and sex of the calves were studied previously (Bayrıl and Yılmaz 2017 ; Mundan et al. 2020 ; Abd-El Hamed and Kamel 2021 ; Özdemir et al. 2022 ; Shalan and Manaa 2022 ; Tankal and Tüzemen 2022 ; Kibar et al. 2024 ). Additionally, several non-linear models have used to determine the best fit function (Val-Arreola et al. 2004 ; Dematawewa et al. 2007 ) and some factors (herd, parity, calving season, calving year) affecting lactation curve traits and persistency in some cattle breeds including Holstein-Friesian cows (Tekerli et al. 2000a ). This study aimed to explore how parity, calving season, and days open influence 305-day milk yield (305-dMY), lactation curve parameters, persistency, time to peak yield (T max ), and peak milk yield (Y max ) in Holstein-Friesian cows raised in Konya province. Material and methods Location and climate of the region In this study, a total of 7607 test day milk yield records of 708 lactation belongs to 373 Holstein Friesian cows were evaluated 2015 to 2019 from a commercial enterprise in Konya province (37.27 °N, 32.74 ° E). Between 2015 and 2019, the lowest and highest temperature averages for the region were − 17.7°C and 36.7°C, respectively. In addition, in terms of average rainfall in these years, the driest month is August (32 mm), while the rainiest month is December (254 mm). Animal husbandry Cows were housed in free stall barns with rubber mat, and barns have headlocks system. There is no fan or water spray system on the farm to cool the cows. Cows were fed ad-libitum in groups according to their milk production levels with total mixed ration (TMR). Preliminary analysis of data Lactation length lower than 220 and greater than 550 days, number of test day records lower than 9 and atypical lactation records were eliminated. After the elimination, 5171 test day milk yield records of 480 lactation belongs to 307 cows were used as research material. In order to estimate lactation curve traits of Wood’s incomplete gamma function ( \(\:{Y}_{t}=a{t}^{b}{e}^{\left(-ct\right)})\) was used with Levenberg-Marquardt iteration (1E-8) in non-linear regression analysis of SPSS ver 24. Adjustment of milk yield to 305 days Total milk yield values were calculated with Holland method. In dairy industry, standard lactation length accepted as 305 days (Beneberu 2023 ). Therefore, shorter or longer than 305-day were calculated according to the adjustment factors (Çilek 2008 ). Holland method: \(\:MY=\:LL\times\:ADMY\) $$\:ADMY=(\sum\:ki)/(\sum\:n)\:\text{v}\text{e}\:LL=na-(a/2-A)$$ Where = MY: total milk yield; ADMY = average daily milk yield; LL = lactation length; k i = milk yield determined in any test day; n = number test days; a = test day interval; A = time between birth to first test day. Modeling of the lactation curve and fixed factors Table 1 Wood equation and the parameters of the lactation curve Traits Equation Wood Function \(\:{Y}_{t}=a{t}^{b}{e}^{\left(-ct\right)}\) T max \(\:b/c\) Y max \(\:a{(b/c)}^{b}{e}^{-b}\) Persistency \(\:-(b+1)\text{ln}\left(c\right)\) Y t : Milk yield on the day t. t: The time between birth to test day; a: The parameter related initial milk yield; b and c: increasing and declining slope parameter of the lactation curve, respectively; T max : Time to peak milk yield (day); Y max : Peak milk yield (kg); e: Natural logarithm base (2,718). 305-dMY, lactation curve parameters, T max , Y max and lactation persistency were analyzed with parity (primipar, multipar), CS (spring: 21 March-20 June, summer: 21 June-22 September, autumn: 23 September-20 December, Winter: 21 December- 20 March), DO (≤ 60 d, 61–90 d, 91–120 d, 121–150 d, 151–180 d, 181–210 d, ≥ 211 d), calving year (2015 through 2019), dry period (≤ 60 d, 61–90 d, ≥ 91 d), calving interval (≤ 360 d, 361–390 d, 391–420 d, 421–450 d, 451–480 d, 481–510 d, 511 ≥ d). Statistical analysis Nonsignificant interactions (P > 0.05) were discarded from the model through backward stepwise elimination. Consequently, according to backward stepwise elimination calving interval were excluded from the model. Also, due to the irregularity of the subgroup data numbers, the dry period factor was also excluded from the model. To analyze the effect of calving season, parity and days open Generalized Linear Mixed model was performed. In the model calving year was evaluated as random factor. The differences between groups were evaluated with Bonferroni correction test. Results Descriptive statistics of the study and least square means (±SD) of fixed factors on 305-dMY were presented in Table 2 and 3, respectively. Table 2- Descriptive statistics of the study Traits Mean Standard deviation Minimum Maximum CV% 305-dMY 8754.30 1503.41 4272.20 12395.60 17.20 Lactation length 362.77 65.93 247 550 18.15 Days open 153.89 69.74 42 407 45.27 a 14.93 4.04 4.68 26.88 27.03 b 0.281 0.067 0.096 0.515 23.92 c 0.0044 0.0012 0.0019 0.0081 27.61 S 7.00 0.27 6.35 7.75 3.79 T max 66.29 13.13 39.70 108.80 19.79 Y max 35.70 6.81 17.97 53.55 19.04 305-dMY: 305-day milk yield, CV%: Coefficient of variation 305-dMY In the study, CS (P<0.05), parity and DO (P<0.001) had showed significant effect on 305-dMY. As seen in the Table 3., multipar cows, cows calving in winter and 151-180-d DO cows produced significantly higher 305-dMY while primipar cows, cows calving in spring and ≤60-d DO cows produced significantly lower 305-dMY. The lowest 305-dMY determined in 60 d DO group while the highest yields in after 151≤ d groups. There was only significant interaction determined between CS and parity (Table 3). While the seasonal difference in primipar cows was the same as the general result, the difference between seasons is insignificant was multipars. Lactation curve traits and persistency Coefficient of determination among fixed factors ranged 85.6% to 93.6%. The effect of parity on lactation curve parameters and lactation persistency were presented in Table 4. Parameter a significantly affected by parity (P<0.001) and days open (P<0.05). Table 3- Least square means ( ±SE) of fixed factors on 305-dMY Parity n 305-dMY Primipar 238 7559.56±125.11 b Multipar 242 9398.54±107.29 a P value *** Calving Season Spring 74 8135.81±180.26 b Summer 70 8283.54±203.96 ab Autumn 138 8647.72±137.63 ab Winter 198 8761.62±117.41 a P value * Days Open ≤60 19 7393.10±347.83 c 61-90 76 8271.87±194.29 bc 91-120 85 8585.71±173.50 ab 121-150 78 8394.06±184.01 bc 151-180 71 9179.14±171.68 a 181-210 53 8532.05±188.56 abc 211≤ 98 8939.16±167.88 ab P value *** Parity × CS * Overall Mean 480 8479.05±82.48 a, b, c Different superscripts in same column within subgroups are statistically different. *: P<0.05; ***: P<0.001. SE: Standard error Parity (P<0.05), CS and DO (P<0.001) showed a significant effect on parameter b. Lactation curves of primipar cows and cows calved in summer showed a stepper incline compared to multipar cows. Also, cows in DO 61-90 d group had the highest parameter b. Also, the parameter was determined to be the lowest in summer calvers. Parameter c significantly affected by CS (P<0.01), parity and DO (P<0.001). The highest parameter c found in multipar cows. Also, cows calved in summer had the highest parameter c. CS (P<0.05), parity and DO (P<0.001) showed a significant effect on lactation persistency (Table 4). As seen in the table, cows calved in autumn and winter are more persistent than cows calved in summer and spring. Also, 151≤ day DO groups showed more persistent lactation curve. In the present study, DO and parity showed a significant effect on T max (P<0.001). In terms of Y max , parity (P<0.001), CS and DO (P<0.01) had a significant impact on peak yield. Multipar cows reached peak milk yield faster than primipar cows. In addition, cows calved in winter had the highest peak yield. In the present study T max effected by both parity and DO (P<0.001). Parity (P<0.001), CS and DO (P<0.01) showed a significant effect on Y max . Primipar cows reached peak yield slowly and have lower peak yield in line with the results of Chen et al. (2016); Sanad and Gharib (2022); Innes et al. (2023). On the other hand cows calved in winter have highest peak yield similar to findings of Khalifa et al. (2018). Table 4. Least square means lactation curve traits and lactation persistency (mean ± SE) Parity n a 1 b c S 2 T max 2 Y max R 2 % Primipar 238 12.75±0.32 b 0.266±0.006 b 0.0039±0.0001 b 7.05±0.02 a 69.3±1.0 a 29.4±0.5 b 90.2 Multipar 242 16.81±0.27 a 0.282±0.006 a 0.0048±0.0001 a 6.86±0.02 b 59.5±0.9 b 39.8±0.4 a 92.9 P value *** * *** *** *** *** Calving season Spring 74 14.75±0.46 0.260±0.009 bc 0.0042±0.0001 ab 6.92±0.03 b 62.5±1.5 33.2±0.7 b 93.6 Summer 70 15.56±0.53 0.246±0.010 c 0.0041±0.0002 b 6.90±0.04 b 62.9±1.7 33.4±0.8 b 92.3 Autumn 138 14.42±0.36 0.289±0.007 ab 0.0046±0.0001 ab 7.00±0.02 a 65.9±1.2 35.4±0.6 ab 90.8 Winter 198 14.43±0.30 0.297±0.006 a 0.0046±0.0001 a 7.00±0.02 a 65.7±1.0 35.9±0.5 a 90.6 P value NS *** ** * NS ** Days open ≤60 19 12.77±0.89 b 0.292±0.018 ab 0.0052±0.0003 a 6.82±0.06 d 56.9±2.9 c 30.5±1.4 b 85.6 61-90 76 13.76±0.50 b 0.302±0.010 a 0.0051±0.0002 a 6.89±0.03 cd 60.3±1.7 c 34.8±0.8 ab 90.2 91-120 85 14.62±0.45 ab 0.286±0.009 ab 0.0046±0.0001 ab 6.94±0.03 abcd 62.6±1.5 bc 35.2±0.7 a 90.7 121-150 78 15.65±0.48 ab 0.255±0.009 b 0.0042±0.0002 bc 6.91±0.03 bcd 62.8±1.6 bc 34.2±0.7 ab 93.4 151-180 71 15.52±0.45 ab 0.275±0.009 ab 0.0040±0.0001 bc 7.06±0.03 a 70.3±1.5 a 37.0±0.7 a 92.6 181-210 53 14.85±0.50 ab 0.256±0.010 b 0.0038±0.0002 c 7.05±0.03 ab 69.9±1.6 a 34.0±0.8 ab 92.4 211≤ 98 16.20±0.44 a 0.253±0.009 b 0.0038±0.0001 c 7.02±0.03 abc 68.3±1.4 ab 36.0±0.7 a 93.7 P value * *** *** *** *** ** 1 Parity × DO * - - - - - 2 CS× DO - - - * * - Overall Mean 480 14.78±0.21 0.274±0.004 0.0044±0.0001 6.96±0.01 64.39±0.67 34.57±0.34 92.0 CS: Calving season, DO: Days open, R 2 : The coefficient of determination, SE: Standard error a, b Means along the same column with different superscripts are significantly (*: P<0.05, **: P<0.01, ***: P<0.001) different. Phenotypic correlations Phenotypic correlations in the present study were given in Table 6. Except Y max -DO, Y max -LL and S-305-dMY, all the correlations were determined significant. Table 6. Phenotypic correlations between the lactation curve traits, 305-dMY, DO and LL Traits b c T max Y max S 305-DMY DO LL a -0.655 ** -0.238 ** -0.451 ** 0.631 ** -0.582 ** 0.652 ** 0.092 * 0.105* b 0.731 ** 0.155 ** 0.125 ** 0.380 ** -0.065 -0.197 ** -0.222** c -0.527 ** 0.281 ** -0.341 ** -0.083 -0.404 ** -0.475** T max -0.241 ** 0.957 ** 0.051 0.346 ** 0.417** Y max -0.219 ** 0.903 ** 0.000 0.009 S 0.018 0.278 ** 0.342** 305-dMY 0.116 * 0.162** DO 0.934** Correlation is significant * (P<0.05) ** (P<0.01) Discussion 305-dMY In terms of milk yield CS (P<0.05), parity and DO (P<0.01) had a significant effect on 305-dMY (Table 3). Multipar cows produced significantly higher 305-dMY than the primipar cows. Similarly, Atashi (2011); Katok and Yanar (2012); Mikóné Jónás et al. (2016); Kino et al. (2019); Masía et al. (2020); Kramarenko and Kramarenko (2022); Poczynek et al. (2023); Evangelista et al. (2024) reported that primipar cows produced lower 305-dMY than multipars. This result probably related with primipar cows’ mammary epithelial cells have not complete the development. On the other hand, with parity increase number of the mammary epithelial cells and activity of them increase too (Sorensen et al. 2006). Also, cows calved in winter had more 305-dMY than calved in spring in this study (Table 3). This might be linked with cows that calved spring reach the peak yield on middle of the summer and exposed to heat stress and milk yield decreases. There are lots of study reports that CS had significant effect on 305-dMY but the highest and the lowest 305-dMY were determined in different seasons (Tekerli et al. 2000b; Rekik et al. 2003; Albarrán-Portillo and Pollott 2011; M’hamdi et al. 2012; Mikóné Jónás et al. 2016; Kino et al. 2019; Poczynek et al. 2023). Wide variation among the seasons may be originated from the differences between climate that cows are breed or management of the herd, maybe taking precautions against adverse weather conditions. In the study 305-dMY were in after 151≤ d groups, while the lowest 305-dMY determined in 60 d DO group. Similarly, in some studies, reports the service period had a significant effect on 305-dMY (Kino et al. 2019; Abd-El Hamed and Kamel 2021). There was only significant interaction determined between CS and parity (Table 3). Interaction açıklanmalı Lactation curve traits and persistency The effect of parity, CS and DO were presented Table 4. Parity (P<0.001) and DO (P<0,05) showed a significant effect on parameter a. Similarly, Wood (1969); Wood (1970); Shanks et al. (1981); Rekik et al. (2003); Darej et al. (2012); Duque et al. (2018); Awad et al. (2022); Marumo et al. (2022); Innes et al. (2023); Evangelista et al. (2024) reported that parity had a significant effect on parameter a. As in 305-dMY, parameter a that known as initial milk yield of the lactation, primipar cows had lowest value maybe related to underdevelopment mammary epithelial cells. As incompatible with this study Tekerli et al. (2000b) determined any significant effect of days open on ln(a). Parameter b of the Wood model significantly affected by parity (P<0.05), CS and DO (P<0.001). As seen in the Table 4, primipar cows and cows calved in summer had a flatter incline slope curve before the peak yield. The results of Atashi et al. (2013); Kramarenko and Kramarenko (2022); Innes et al. (2023) in agreement with this study which were reported that parameter b increase with the parity increase. Similarly Atashi et al. (2009) reported that the parameter b the highest in cows calved in winter. The results of Atashi et al. (2013); Kramarenko and Kramarenko (2022); Innes et al. (2023) in agreement with this study which were reported that parameter b increase with the parity increase. Similarly Atashi et al. (2009) reported that the parameter b the highest in cows calved in winter. Also 61-90 DO group has a steeper incline slope curve till the peak production. Similar to this study significant effect of DO on parameter b reported by Tekerli et al. (2000b); Ruban et al. (2022). CS (P<0.01), parity and DO (P<0.001) showed a significant effect on parameter c. As seen Table 4, the parameter c was found to be the highest in multipar cows similar to findings of Darej et al. (2012); Atashi et al. (2013); Innes et al. (2023). Parameter c represents the decline in milk yield after peak yield in lactation curve. This most likely linked with mammary cells are more active in multipar cows’ and thus milk yield rapidly declines after peak. Also, cows calved in summer had the lowest parameter c value while cows calved in winter had the highest. Atashi et al. (2009) determined the parameter c highest in winter calver cows parallel to our result. This might be related with cows calved in winter reach peak yield early and thus milk yield rapidly declines. Lactation persistency significantly affected by CS (P<0.05), parity and DO (P<0.001). This may be associated with primipar cows’ mammary cell renewal are better and have lower somatic cell score, high serum and mammary concentrations of insulin-like growth hormone 1 (IGF-1), which enables mammary glands to proliferate by mitosis, positive correlation between lactation persistency and IGF-1, explain why lactation persistency is higher in the first lactation (Schutz et al. 1990; Weber et al. 2000; Sorensen and Knight 2002; Miller et al. 2006; Webster et al. 2024). Also, cows calved in autumn and winter are more persistent than cows calved in summer and spring in line with the results of Khalifa et al. (2018); Ruban et al. (2022). Moreover, in some studies the effect of days open on parameter c were reported significant in agreement to this study (Tekerli et al. 2000b; Ruban et al. 2022). In the study, parameter c decreases with the days open increase while lactation persistency increase probably caused by negative affect of pregnancy hormones (Yart et al. 2012; Chen et al. 2024). In the present study T max effected by both parity and DO (P<0.001). Parity (P<0.001), CS and DO (P<0.01) showed a significant effect on Y max . Primipar cows reached peak yield slowly and have lower peak yield in line with the results of Chen et al. (2016); Sanad and Gharib (2022); Innes et al. (2023); Evangelista et al. (2024). On the other hand cows calved in winter have highest peak yield similar to findings of Khalifa et al. (2018). Phenotypic correlations As seen in Table 6, a significant negative correlation (-0.655) between parameters a and b indicates that a higher initial milk yield is associated with a slower rate of increase in milk production, resulting in a more gradual progression to peak yield. Also, positive significant correlation (0.731) between parameter b and c indicates that rapidly incline in milk yield at the same time would rapidly decline after peak. High positive correlation (0.957) between T max and S; and negative correlation (-0.341) between parameter c and S means that cows which reach later to peak yield and slow decline after peak are more persistent. Contrarily, because of the fact that significant negative correlation between S and Y max (-0.219), cows with higher persistency have lower peak yield. According the positive (0.631) and negative (0.582) significant correlations cows that higher initial milk yield have more peak milk yield but lower persistency. In addition, positive significant correlations between 305-dMY and parameter a-Y max (0.652; 0.903) indicates that higher initial and peak yield caused higher 305-dMY. These findings in agreement with the reports of Tekerli et al. (2000b); Saghanezhad et al. (2017); Awad et al. (2022); Sanad and Gharib (2022); Zamorano-Algandar et al. (2022). Moreover, positive significant correlation between DO and S-305-dMY (0.278; 0.116) explained that with DO length increase 305-dMY and S increases. As expected, when the DO increase T max increase but parameter b and c decreases. Conclusion Dairy cows’ milk yield and lactation curve affected by lots of environmental factors. This study shows that parity, calving season, and days open (DO) have a strong effect on milk yield and lactation traits in Holstein-Friesian cows. Multiparous cows and cows that calve in winter produced higher milk yields over 305 days, while primiparous cows, though yielding less, maintained milk production for a longer time. Seasonal differences were also observed, with cows calving in autumn and winter reaching higher peak milk production and having better persistency. Additionally, the length of the days open period was crucial, as cows with 151–180 days open achieved the best results, while shorter intervals (≤ 60 days) led to lower production and persistency. These findings underline the importance of tailoring herd management strategies by considering parity, calving season, and days open to improve milk yield and efficiency. By using these insights, dairy farmers can make practical adjustments that lead to higher productivity, sustainable practices, and stronger economic outcomes in the dairy industry. Declarations The experimental procedure has been accepted by Ethics Committee of Selcuk University Faculty of Veterinary Experimental Animals Production and Research Centre (Permit No.2020/91, date of approval: 27.10.2020). Acknowledgements This study was derived from corresponding author's Phd Thesis accepted in 2023 by ………………………... Thanks to ………………………………. authority for sharing the farms' data. Author Contributions Serdar Güler conceptualization, data collection and curation, perform analysis, writing first draft of the manuscript were performed by Serdar Güler; data collecting permission from enterprise and supervision of the study, review and editing the manuscript performed by Ali Akmaz. Final manuscript read and agreed by both authors. Data Availability Statement The datasets generated and analyzed during this study are available from the corresponding author upon reasonable request. Funding The authors did not report any financial support. 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Acta Univ Agric Silvic Mendelianae Brun 70(6): 373-382. https://doi.org/10.11118/actaun.2022.028 Saghanezhad F, Atashi H, Dadpasand M, Zamiri MJ, Shokri-Sangari F (2017) Estimation of genetic parameters for lactation curve traits in Holstein Dairy Cows in Iran. IJAS 7(4): 559-566. Sanad S, Gharib MG (2022) Genetic and non-genetic estimates of lactation curve in Friesian cows. Egyptian J Anim Prod 59(4): 83-89. https://doi.org/10.21608/ejap.2022.244957 Schutz MM, Hansen LB, Steuernagel GR, Kuck AL (1990) Variation of milk, fat, protein, and somatic cells for dairy cattle. J Dairy Sci 73(2): 484-493. https://doi.org/10.3168/jds.S0022-0302(90)78696-1 Shalan S, Manaa E (2022) Evaluation of some genetic and non-genetic factors influencing 305-DMY, TMY and breeding values in Holstein Friesian cows. BVMJ 41(2): 88-92. https://doi.org/10.21608/bvmj.2021.92213.1463 Shanks RD, Berger PJ, Freeman AE, Dickinson FN (1981) Genetic-aspects of lactation curves. J Dairy Sci 64(9): 1852-1860. https://doi.org/10.3168/jds.S0022-0302(81)82775-0 Sorensen A, Knight CH (2002) Endocrine profiles of cows undergoing extended lactation in relation to the control of lactation persistency. Domest Anim Endocrinol 23(1-2): 111-123. https://doi.org/10.1016/S0739-7240(02)00150-9 Sorensen MT, Nørgaard JV, Theil PK, Vestergaard M, Sejrsen K (2006) Cell turnover and activity in mammary tissue during lactation and the dry period in dairy cows. J Dairy Sci 89(12): 4632-4639. https://doi.org/10.3168/jds.S0022-0302(06)72513-9 Tankal M, Tüzemen N (2022) Gökkale Tarım İşletmesinde yetiştirilen siyah alaca sığırların süt ve döl verimi özellikleri. PASTE 1(2): 14-22. Tekerli M, Akinci Z, Dogan I, Akcan A (2000a) Factors affecting the shape of lactation curves of Holstein cows from the Balikesir province of Turkey. J Dairy Sci 83(6): 1381-1386. https://doi.org/10.3168/jds.S0022-0302(00)75006-5 Tekerli M, Akinci Z, Dogan I, Akcan A (2000b) Factors affecting the shape of lactation curves of Holstein cows from the Balikesir Province of Turkey. J Dairy Sci 83(6): 1381-1386. https://doi.org/10.3168/jds.S0022-0302(00)75006-5 Torshizi ME, Mashhadi MH, Farhangfar H (2019) Different aspects of lactation persistency in dairy cows. Indian J Anim Sci 89(6): 607-614. Val-Arreola D, Kebreab E, Dijkstra J, France J (2004) Study of the lactation curve in dairy cattle on farms in central Mexico. J Dairy Sci 87(11): 3789-3799. https://doi.org/10.3168/jds.S0022-0302(04)73518-3 Weber MS, Purup S, Vestergaard M, Akers RM, Sejrsen K (2000) Regulation of local synthesis of insulin-like growth factor-I and binding proteins in mammary tissue. J Dairy Sci 83(1): 30-37. https://doi.org/10.3168/jds.S0022-0302(00)74851-X Webster HH, Lengi AJ, Corl BA (2024) Mammary epithelial cell exfoliation increases as milk yield declines, lactation progresses, and parity increases. JDS Communications 5(6): 707-712. https://doi.org/10.3168/jdsc.2023-0534 Wood PDP (1967) Algebraic model of the lactation curve in cattle. Nature 216 164-165. https://doi.org/10.1038/216164a0 Wood PDP (1969) Factors affecting the shape of the lactation curve in cattle. Anim Prod 11(3): 307-316. https://doi.org/10.1017/S0003356100026945 Wood PDP (1970) A note on the repeatability of parameters of the lactation curve in cattle. Anim Prod 12(3): 535-538. https://doi.org/10.1017/S0003356100029135 Yart L, Dessauge F, Finot L, Barbey S, Marnet P-G, Lollivier V (2012) Ovariectomy improves lactation persistency in dairy cows. J Dairy Sci 95(7): 3794-3802. https://doi.org/10.3168/jds.2011-5195 Zamorano-Algandar R, Medrano JF, Thomas MG, Enns RM, Speidel SE, Sánchez-Castro MA, Luna-Nevárez G, Leyva-Corona JC, Luna-Nevárez P (2022) Effect of calving season on the parameters and components of the lactation curve in Holstein dairy cows managed in a semi-desert climate. Trop Anim Health Prod 54(2): 88. https://doi.org/10.1007/s11250-022-03098-7 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted 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. 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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-6440916","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":442345196,"identity":"2063c194-218b-4fcc-bf4a-483e2cfed77a","order_by":0,"name":"Serdar Güler","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA/UlEQVRIiWNgGAWjYFAC5gYoI4GB4QMbmGVAQAsjQgvjDLiWBCK1MPMQo0U+IrHxcQVDnZx5e/KzzzZlNokN7M3bJBh/3MOpxfBGYrPhGYbDxjJnnhnPzjmXltjAc6xMgiGhGLeWGYltkg0MBxJnSCQYM+e2HU5skMgxA2rB7TKglvafDQx19TMk0j8zW7b9T2yQf4Nfi7xEYhswAJgTJCRyjJkZ2w4AbeHBr8WA52GzZIPBYcMZPG+KGXvOJRu38aQVWySk4bGlPfngx4aKOnkJ9vTNDD/K7GT72Q9vvPHBBo8tB8Akkgg4anBrANrSgEdyFIyCUTAKRgEYAABN1k4KNbfMxgAAAABJRU5ErkJggg==","orcid":"","institution":"Dokuz Eylül University","correspondingAuthor":true,"prefix":"","firstName":"Serdar","middleName":"","lastName":"Güler","suffix":""},{"id":442345198,"identity":"602e5f32-62e3-434e-8c29-0f28778cfb4d","order_by":1,"name":"Ali Akmaz","email":"","orcid":"","institution":"Selcuk University","correspondingAuthor":false,"prefix":"","firstName":"Ali","middleName":"","lastName":"Akmaz","suffix":""}],"badges":[],"createdAt":"2025-04-13 19:53:14","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6440916/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6440916/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":80700112,"identity":"f72408d2-78e8-4afd-b044-61dee093be1d","added_by":"auto","created_at":"2025-04-16 07:35:59","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":22503,"visible":true,"origin":"","legend":"\u003cp\u003eLactation curves according to the parity\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6440916/v1/e75f3873ca1ff5983b5fc02c.png"},{"id":80698489,"identity":"32b7ddd9-3993-4558-9f28-fa2107015c3f","added_by":"auto","created_at":"2025-04-16 07:19:59","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":32589,"visible":true,"origin":"","legend":"\u003cp\u003eLactation curves according to the calving season\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6440916/v1/728633c67d849dc41ed144a5.png"},{"id":80698490,"identity":"5d440070-f525-4469-84f3-00d87b5ef4fd","added_by":"auto","created_at":"2025-04-16 07:19:59","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":56079,"visible":true,"origin":"","legend":"\u003cp\u003eLactation curves according to the days open\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6440916/v1/ec434b7cb2c8607e58e6a885.png"},{"id":81222612,"identity":"1579ea88-ceef-431b-8a98-e2874c5dc5f3","added_by":"auto","created_at":"2025-04-23 15:31:51","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1016642,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6440916/v1/450fb799-aefb-4604-813d-f9182a69accd.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Evaluating Lactation Persistency, Lactation Curve Parameters, and Dairy Efficiency: The Role of Parity, Calving Season, and Days Open in Holstein-Friesian Cows","fulltext":[{"header":"Introduction","content":"\u003cp\u003eLactation is a complex process that consists milk synthesis, secretion and some of the mammary gland development stage (Mukherjee et al. \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Level of the milk production has an economic impact on dairy farms. One of the most important indicator of the level of milk yield is lactation persistency (G\u0026uuml;ler and Akmaz \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Lactation persistency is defined as continuity of the milk yield after the lactation peak and shape of the lactation curve determines the persistency (G\u0026uuml;ler and Akmaz \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Angeles-Hernandez et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). A standard lactation curve consists of three phases, initial milk yield, increasing slope and decreasing slope until the dry of (G\u0026uuml;ler and Akmaz \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Angeles-Hernandez et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Sanad and Gharib \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). To make critical decisions in dairy farms, estimating shape of the lactation curve is crucial because of the fact that lactation persistency is an economical trait impacts feed costs, fertility and health (Dekkers et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e1998\u003c/span\u003e; Piccardi et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Oliveira et al. \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Lactation curve and its traits, thus milk yield affected by both genetic and environmental factors such as parity, season of calving, season of month, calving year, calving age and dry period length (G\u0026uuml;ler and Akmaz \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn a lot of cattle breeds including Holstein-Friesian several non-linear functions were widely used by the researchers to determine the lactation curve parameters and the lactation persistency for decades (Tekerli et al. \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2000b\u003c/span\u003e; Kopec et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Otwinowska-Mindur et al. \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Chiba et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Hern\u0026aacute;ndez-Zamudio et al. \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Although a lot of nonlinear functions were developed to determine the lactation curve traits and lactation persistency since beginning first quarter of the 20th century, a gamma function called Wood model (Wood \u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e1967\u003c/span\u003e) were mostly used still in nowadays.\u003c/p\u003e \u003cp\u003eThe effect of parity and season of calving (Tankal and T\u0026uuml;zemen \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) and days open (Abd-El Hamed and Kamel \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) on 305-dMY, also determined to be significant in some studies. In previous studies the effect of parity on parameter a, b and c (Wood \u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e1969\u003c/span\u003e; Wood \u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e1970\u003c/span\u003e; Rowlands et al. \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e1982\u003c/span\u003e; Darej et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2012\u003c/span\u003e), lactation persistency (Tekerli et al. \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2000b\u003c/span\u003e; Rekik et al. \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2003\u003c/span\u003e; Albarr\u0026aacute;n-Portillo and Pollott \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Atashi et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Torshizi et al. \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Jiang et al. \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Lee et al. \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), T\u003csub\u003emax\u003c/sub\u003e and Y\u003csub\u003emax\u003c/sub\u003e (Tekerli et al. \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2000b\u003c/span\u003e; Rekik et al. \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2003\u003c/span\u003e; Jiang et al. \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Mas\u0026iacute;a et al. \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) were studied. Also, significant effect of calving season on parameter a (Bouallegue et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2014\u003c/span\u003e), parameter b and c (Atashi et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2009\u003c/span\u003e), lactation persistency (Kopec et al. \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Khalifa et al. \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), T\u003csub\u003emax\u003c/sub\u003e and Y\u003csub\u003emax\u003c/sub\u003e (Sanad and Gharib \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) were reported. In addition of days open on parameter b and c (Tekerli et al. \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2000b\u003c/span\u003e), lactation persistency (Ruban et al. \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2022\u003c/span\u003e), T\u003csub\u003emax\u003c/sub\u003e (Lopez-Villalobos et al. \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2005\u003c/span\u003e) and Y\u003csub\u003emax\u003c/sub\u003e (Al-Atiyat et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e1999\u003c/span\u003e) were determined.\u003c/p\u003e \u003cp\u003eSeveral factors effect on 305-dMY such as parity, calving season, calving month, calving year, age at first calving, calving interval, days open, dry period and sex of the calves were studied previously (Bayrıl and Yılmaz \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Mundan et al. \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Abd-El Hamed and Kamel \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; \u0026Ouml;zdemir et al. \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Shalan and Manaa \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Tankal and T\u0026uuml;zemen \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Kibar et al. \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Additionally, several non-linear models have used to determine the best fit function (Val-Arreola et al. \u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e2004\u003c/span\u003e; Dematawewa et al. \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2007\u003c/span\u003e) and some factors (herd, parity, calving season, calving year) affecting lactation curve traits and persistency in some cattle breeds including Holstein-Friesian cows (Tekerli et al. \u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e2000a\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThis study aimed to explore how parity, calving season, and days open influence 305-day milk yield (305-dMY), lactation curve parameters, persistency, time to peak yield (T\u003csub\u003emax\u003c/sub\u003e), and peak milk yield (Y\u003csub\u003emax\u003c/sub\u003e) in Holstein-Friesian cows raised in Konya province.\u003c/p\u003e"},{"header":"Material and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eLocation and climate of the region\u003c/h2\u003e \u003cp\u003eIn this study, a total of 7607 test day milk yield records of 708 lactation belongs to 373 Holstein Friesian cows were evaluated 2015 to 2019 from a commercial enterprise in Konya province (37.27 \u0026deg;N, 32.74 \u0026deg; E). Between 2015 and 2019, the lowest and highest temperature averages for the region were \u0026minus;\u0026thinsp;17.7\u0026deg;C and 36.7\u0026deg;C, respectively. In addition, in terms of average rainfall in these years, the driest month is August (32 mm), while the rainiest month is December (254 mm).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eAnimal husbandry\u003c/h3\u003e\n\u003cp\u003eCows were housed in free stall barns with rubber mat, and barns have headlocks system. There is no fan or water spray system on the farm to cool the cows. Cows were fed \u003cem\u003ead-libitum\u003c/em\u003e in groups according to their milk production levels with total mixed ration (TMR).\u003c/p\u003e\n\u003ch3\u003ePreliminary analysis of data\u003c/h3\u003e\n\u003cp\u003eLactation length lower than 220 and greater than 550 days, number of test day records lower than 9 and atypical lactation records were eliminated. After the elimination, 5171 test day milk yield records of 480 lactation belongs to 307 cows were used as research material. In order to estimate lactation curve traits of Wood\u0026rsquo;s incomplete gamma function (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{Y}_{t}=a{t}^{b}{e}^{\\left(-ct\\right)})\\)\u003c/span\u003e\u003c/span\u003e was used with Levenberg-Marquardt iteration (1E-8) in non-linear regression analysis of SPSS ver 24.\u003c/p\u003e\n\u003ch3\u003eAdjustment of milk yield to 305 days\u003c/h3\u003e\n\u003cp\u003eTotal milk yield values were calculated with Holland method. In dairy industry, standard lactation length accepted as 305 days (Beneberu \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Therefore, shorter or longer than 305-day were calculated according to the adjustment factors (\u0026Ccedil;ilek \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2008\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eHolland method: \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:MY=\\:LL\\times\\:ADMY\\)\u003c/span\u003e\u003c/span\u003e\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\:ADMY=(\\sum\\:ki)/(\\sum\\:n)\\:\\text{v}\\text{e}\\:LL=na-(a/2-A)$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWhere =\u0026thinsp;MY: total milk yield; ADMY\u0026thinsp;=\u0026thinsp;average daily milk yield; LL\u0026thinsp;=\u0026thinsp;lactation length; k\u003csub\u003ei\u003c/sub\u003e= milk yield determined in any test day; n\u0026thinsp;=\u0026thinsp;number test days; a\u0026thinsp;=\u0026thinsp;test day interval; A\u0026thinsp;=\u0026thinsp;time between birth to first test day.\u003c/p\u003e\n\u003ch3\u003eModeling of the lactation curve and fixed factors\u003c/h3\u003e\n\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\u003eWood equation and the parameters of the lactation curve\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eTraits\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eEquation\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWood Function\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{Y}_{t}=a{t}^{b}{e}^{\\left(-ct\\right)}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT\u003csub\u003emax\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:b/c\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eY\u003csub\u003emax\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:a{(b/c)}^{b}{e}^{-b}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePersistency\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:-(b+1)\\text{ln}\\left(c\\right)\\)\u003c/span\u003e\u003c/span\u003e\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\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eY\u003csub\u003e\u003cb\u003et\u003c/b\u003e\u003c/sub\u003e: Milk yield on the day t. t: The time between birth to test day; a: The parameter related initial milk yield; b and c: increasing and declining slope parameter of the lactation curve, respectively; T\u003csub\u003emax\u003c/sub\u003e: Time to peak milk yield (day); Y\u003csub\u003emax\u003c/sub\u003e: Peak milk yield (kg); e: Natural logarithm base (2,718).\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e305-dMY, lactation curve parameters, T\u003csub\u003emax\u003c/sub\u003e, Y\u003csub\u003emax\u003c/sub\u003e and lactation persistency were analyzed with parity (primipar, multipar), CS (spring: 21 March-20 June, summer: 21 June-22 September, autumn: 23 September-20 December, Winter: 21 December- 20 March), DO (\u0026le;\u0026thinsp;60 d, 61\u0026ndash;90 d, 91\u0026ndash;120 d, 121\u0026ndash;150 d, 151\u0026ndash;180 d, 181\u0026ndash;210 d, \u0026ge;\u0026thinsp;211 d), calving year (2015 through 2019), dry period (\u0026le;\u0026thinsp;60 d, 61\u0026ndash;90 d, \u0026ge;\u0026thinsp;91 d), calving interval (\u0026le;\u0026thinsp;360 d, 361\u0026ndash;390 d, 391\u0026ndash;420 d, 421\u0026ndash;450 d, 451\u0026ndash;480 d, 481\u0026ndash;510 d, 511\u0026thinsp;\u0026ge;\u0026thinsp;d).\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eNonsignificant interactions (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05) were discarded from the model through backward stepwise elimination. Consequently, according to backward stepwise elimination calving interval were excluded from the model. Also, due to the irregularity of the subgroup data numbers, the dry period factor was also excluded from the model. To analyze the effect of calving season, parity and days open Generalized Linear Mixed model was performed. In the model calving year was evaluated as random factor. The differences between groups were evaluated with Bonferroni correction test.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eDescriptive statistics of the study and least square means (\u0026plusmn;SD) of fixed factors on 305-dMY were presented in Table 2 and 3, respectively.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2- Descriptive statistics of the study\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"537\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003e\u003cem\u003eTraits\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 64px;\"\u003e\n \u003cp\u003e\u003cem\u003eMean\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 134px;\"\u003e\n \u003cp\u003e\u003cem\u003eStandard deviation\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e\u003cem\u003eMinimum\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cem\u003eMaximum\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e\u003cem\u003eCV%\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003e305-dMY\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e8754.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 134px;\"\u003e\n \u003cp\u003e1503.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 73px;\"\u003e\n \u003cp\u003e4272.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e12395.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e17.20\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003eLactation length\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 64px;\"\u003e\n \u003cp\u003e362.77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 134px;\"\u003e\n \u003cp\u003e65.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e247\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 76px;\"\u003e\n \u003cp\u003e550\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e18.15\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003eDays open\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 64px;\"\u003e\n \u003cp\u003e153.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 134px;\"\u003e\n \u003cp\u003e69.74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 76px;\"\u003e\n \u003cp\u003e407\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e45.27\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003ea\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 64px;\"\u003e\n \u003cp\u003e14.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 134px;\"\u003e\n \u003cp\u003e4.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e4.68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 76px;\"\u003e\n \u003cp\u003e26.88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e27.03\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003eb\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 64px;\"\u003e\n \u003cp\u003e0.281\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 134px;\"\u003e\n \u003cp\u003e0.067\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e0.096\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0.515\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e23.92\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003ec\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 64px;\"\u003e\n \u003cp\u003e0.0044\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 134px;\"\u003e\n \u003cp\u003e0.0012\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e0.0019\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0.0081\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e27.61\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003eS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 64px;\"\u003e\n \u003cp\u003e7.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 134px;\"\u003e\n \u003cp\u003e0.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e6.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 76px;\"\u003e\n \u003cp\u003e7.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e3.79\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003eT\u003csub\u003emax\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 64px;\"\u003e\n \u003cp\u003e66.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 134px;\"\u003e\n \u003cp\u003e13.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e39.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 76px;\"\u003e\n \u003cp\u003e108.80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e19.79\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 123px;\"\u003e\n \u003cp\u003eY\u003csub\u003emax\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 64px;\"\u003e\n \u003cp\u003e35.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 134px;\"\u003e\n \u003cp\u003e6.81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 73px;\"\u003e\n \u003cp\u003e17.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 76px;\"\u003e\n \u003cp\u003e53.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e19.04\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e305-dMY: 305-day milk yield, CV%: Coefficient of variation\u003c/p\u003e\n\u003ch2\u003e305-dMY\u003c/h2\u003e\n\u003cp\u003eIn the study, CS (P\u0026lt;0.05), parity and DO (P\u0026lt;0.001) had showed significant effect on 305-dMY. As seen in the Table 3., multipar cows, cows calving in winter and 151-180-d DO cows produced significantly higher 305-dMY while primipar cows, cows calving in spring and \u0026le;60-d DO cows produced significantly lower 305-dMY. The lowest 305-dMY determined in 60 d DO group while the highest yields in after 151\u0026le; d groups.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThere was only significant interaction determined between CS and parity (Table 3). While the seasonal difference in primipar cows was the same as the general result, the difference between seasons is insignificant was multipars.\u003c/p\u003e\n\u003ch2\u003eLactation curve traits and persistency\u003c/h2\u003e\n\u003cp\u003eCoefficient of determination among fixed factors ranged 85.6% to 93.6%. The effect of parity on lactation curve parameters and lactation persistency were presented in Table 4. Parameter a significantly affected by parity (P\u0026lt;0.001) and days open (P\u0026lt;0.05).\u0026nbsp;\u003c/p\u003e\n\u003cp id=\"_Toc125468643\"\u003e\u003cstrong\u003eTable\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e3- Least square means (\u003c/strong\u003e\u003cstrong\u003e\u0026plusmn;SE) of fixed factors on 305-dMY\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"359\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e\u003cem\u003eParity\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cem\u003en\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 142px;\"\u003e\n \u003cp\u003e\u003cem\u003e305-dMY\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003ePrimipar\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e238\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 142px;\"\u003e\n \u003cp\u003e7559.56\u0026plusmn;125.11\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003eMultipar\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e242\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 142px;\"\u003e\n \u003cp\u003e9398.54\u0026plusmn;107.29\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003eP value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 142px;\"\u003e\n \u003cp\u003e***\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003eCalving Season\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 142px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003eSpring\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 142px;\"\u003e\n \u003cp\u003e8135.81\u0026plusmn;180.26\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003eSummer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 142px;\"\u003e\n \u003cp\u003e8283.54\u0026plusmn;203.96\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003eAutumn\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e138\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 142px;\"\u003e\n \u003cp\u003e8647.72\u0026plusmn;137.63\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003eWinter\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e198\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 142px;\"\u003e\n \u003cp\u003e8761.62\u0026plusmn;117.41\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003eP value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 142px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003eDays Open\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 142px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e\u0026le;60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 142px;\"\u003e\n \u003cp\u003e7393.10\u0026plusmn;347.83\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e61-90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 142px;\"\u003e\n \u003cp\u003e8271.87\u0026plusmn;194.29\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e91-120\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 142px;\"\u003e\n \u003cp\u003e8585.71\u0026plusmn;173.50\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e121-150\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 142px;\"\u003e\n \u003cp\u003e8394.06\u0026plusmn;184.01\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e151-180\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 142px;\"\u003e\n \u003cp\u003e9179.14\u0026plusmn;171.68\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e181-210\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 142px;\"\u003e\n \u003cp\u003e8532.05\u0026plusmn;188.56\u003csup\u003eabc\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e211\u0026le;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 142px;\"\u003e\n \u003cp\u003e8939.16\u0026plusmn;167.88\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003eP value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 142px;\"\u003e\n \u003cp\u003e***\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003eParity \u0026times; CS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 142px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003eOverall Mean\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e480\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 142px;\"\u003e\n \u003cp\u003e8479.05\u0026plusmn;82.48\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003csup\u003ea, b, c\u003c/sup\u003e Different superscripts in same column within subgroups are statistically different. *: P\u0026lt;0.05; ***: P\u0026lt;0.001. SE: Standard error\u003c/p\u003e\n\u003cp\u003eParity (P\u0026lt;0.05), CS and DO (P\u0026lt;0.001) showed a significant effect on parameter b. Lactation curves of primipar cows and cows calved in summer showed a stepper incline compared to multipar cows. Also, cows in DO 61-90 d group had the highest parameter b. Also, the parameter was determined to be the lowest in summer calvers.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eParameter c significantly affected by CS (P\u0026lt;0.01), parity and DO (P\u0026lt;0.001). The highest parameter c found in multipar cows. Also, cows calved in summer had the highest parameter c.\u003c/p\u003e\n\u003cp\u003eCS (P\u0026lt;0.05), parity and DO (P\u0026lt;0.001) showed a significant effect on lactation persistency (Table 4). As seen in the table, cows calved in autumn and winter are more persistent than cows calved in summer and spring. Also, 151\u0026le; day DO groups showed more persistent lactation curve.\u003c/p\u003e\n\u003cp\u003eIn the present study, DO and parity showed a significant effect on T\u003csub\u003emax\u003c/sub\u003e (P\u0026lt;0.001). In terms of Y\u003csub\u003emax\u003c/sub\u003e, parity (P\u0026lt;0.001), CS and DO (P\u0026lt;0.01) had a significant impact on peak yield. Multipar cows reached peak milk yield faster than primipar cows. In addition, cows calved in winter had the highest peak yield.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn the present study T\u003csub\u003emax\u003c/sub\u003e effected by both parity and DO (P\u0026lt;0.001). Parity (P\u0026lt;0.001), CS and DO (P\u0026lt;0.01) showed a significant effect on Y\u003csub\u003emax\u003c/sub\u003e. Primipar cows reached peak yield slowly and have lower peak yield in line with the results of Chen et al. (2016); Sanad and Gharib (2022); Innes et al. (2023). On the other hand cows calved in winter have highest peak yield similar to findings of Khalifa et al. (2018). \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 4.\u003c/strong\u003e Least square means lactation curve traits and lactation persistency (mean \u0026plusmn; SE)\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"709\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003cem\u003eParity\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e\u003cem\u003en\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u003cem\u003ea\u003csup\u003e1\u003c/sup\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u003cem\u003eb\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003cem\u003ec\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u003cem\u003eS\u003csup\u003e2\u003c/sup\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cem\u003eT\u003csub\u003emax\u003c/sub\u003e\u003csup\u003e2\u003c/sup\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cem\u003eY\u003csub\u003emax\u003c/sub\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e\u003cem\u003eR\u003csup\u003e2\u003c/sup\u003e%\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003ePrimipar\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e238\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e12.75\u0026plusmn;0.32\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.266\u0026plusmn;0.006\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e0.0039\u0026plusmn;0.0001\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e7.05\u0026plusmn;0.02\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e69.3\u0026plusmn;1.0\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e29.4\u0026plusmn;0.5\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e90.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eMultipar\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e242\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e16.81\u0026plusmn;0.27\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.282\u0026plusmn;0.006\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e0.0048\u0026plusmn;0.0001\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e6.86\u0026plusmn;0.02\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e59.5\u0026plusmn;0.9\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e39.8\u0026plusmn;0.4\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e92.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eP value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e***\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003e***\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 85px;\"\u003e\n \u003cp\u003e***\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e***\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e***\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eCalving season\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eSpring\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e14.75\u0026plusmn;0.46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.260\u0026plusmn;0.009\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e0.0042\u0026plusmn;0.0001\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e6.92\u0026plusmn;0.03\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e62.5\u0026plusmn;1.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e33.2\u0026plusmn;0.7\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e93.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eSummer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e15.56\u0026plusmn;0.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.246\u0026plusmn;0.010\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e0.0041\u0026plusmn;0.0002\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e6.90\u0026plusmn;0.04\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e62.9\u0026plusmn;1.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e33.4\u0026plusmn;0.8\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e92.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eAutumn\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e138\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e14.42\u0026plusmn;0.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.289\u0026plusmn;0.007\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e0.0046\u0026plusmn;0.0001\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e7.00\u0026plusmn;0.02\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e65.9\u0026plusmn;1.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e35.4\u0026plusmn;0.6\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e90.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eWinter\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e198\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e14.43\u0026plusmn;0.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.297\u0026plusmn;0.006\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e0.0046\u0026plusmn;0.0001\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e7.00\u0026plusmn;0.02\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e65.7\u0026plusmn;1.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e35.9\u0026plusmn;0.5\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e90.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eP value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003eNS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e***\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003eNS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eDays open\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u0026le;60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e12.77\u0026plusmn;0.89\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.292\u0026plusmn;0.018\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e0.0052\u0026plusmn;0.0003\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e6.82\u0026plusmn;0.06\u003csup\u003ed\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e56.9\u0026plusmn;2.9\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e30.5\u0026plusmn;1.4\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e85.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e61-90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e13.76\u0026plusmn;0.50\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.302\u0026plusmn;0.010\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e0.0051\u0026plusmn;0.0002\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e6.89\u0026plusmn;0.03\u003csup\u003ecd\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e60.3\u0026plusmn;1.7\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e34.8\u0026plusmn;0.8\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e90.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e91-120\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e14.62\u0026plusmn;0.45\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.286\u0026plusmn;0.009\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e0.0046\u0026plusmn;0.0001\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e6.94\u0026plusmn;0.03\u003csup\u003eabcd\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e62.6\u0026plusmn;1.5\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e35.2\u0026plusmn;0.7\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e90.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e121-150\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e15.65\u0026plusmn;0.48\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.255\u0026plusmn;0.009\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e0.0042\u0026plusmn;0.0002\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e6.91\u0026plusmn;0.03\u003csup\u003ebcd\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e62.8\u0026plusmn;1.6\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e34.2\u0026plusmn;0.7\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e93.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e151-180\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e15.52\u0026plusmn;0.45\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.275\u0026plusmn;0.009\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e0.0040\u0026plusmn;0.0001\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e7.06\u0026plusmn;0.03\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e70.3\u0026plusmn;1.5\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e37.0\u0026plusmn;0.7\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e92.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e181-210\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e14.85\u0026plusmn;0.50\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.256\u0026plusmn;0.010\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e0.0038\u0026plusmn;0.0002\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e7.05\u0026plusmn;0.03\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e69.9\u0026plusmn;1.6\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e34.0\u0026plusmn;0.8\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e92.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e211\u0026le;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e16.20\u0026plusmn;0.44\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.253\u0026plusmn;0.009\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e0.0038\u0026plusmn;0.0001\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e7.02\u0026plusmn;0.03\u003csup\u003eabc\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e68.3\u0026plusmn;1.4\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e36.0\u0026plusmn;0.7\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e93.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eP value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e***\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e***\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e***\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e***\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003csup\u003e1\u003c/sup\u003eParity \u0026times; DO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003csup\u003e2\u003c/sup\u003eCS\u0026times; DO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eOverall Mean\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e480\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e14.78\u0026plusmn;0.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.274\u0026plusmn;0.004\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e0.0044\u0026plusmn;0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e6.96\u0026plusmn;0.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e64.39\u0026plusmn;0.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e34.57\u0026plusmn;0.34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 38px;\"\u003e\n \u003cp\u003e92.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eCS: Calving season, DO: Days open, R\u003csup\u003e2\u003c/sup\u003e: The coefficient of determination, SE: Standard error\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003csup\u003ea, b\u0026nbsp;\u003c/sup\u003eMeans along the same column with different superscripts are significantly (*: P\u0026lt;0.05, **: P\u0026lt;0.01, ***: P\u0026lt;0.001) different.\u0026nbsp;\u003c/p\u003e\n\u003ch2\u003ePhenotypic correlations\u003c/h2\u003e\n\u003cp\u003ePhenotypic correlations in the present study were given in Table 6. Except Y\u003csub\u003emax\u003c/sub\u003e-DO, Y\u003csub\u003emax\u003c/sub\u003e-LL and S-305-dMY, all the correlations were determined significant.\u003c/p\u003e\n\u003cp\u003eTable 6. \u0026nbsp;Phenotypic correlations between the lactation curve traits, 305-dMY, DO and LL\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"558\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e\u0026nbsp;Traits\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003eb\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003ec\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 59px;\"\u003e\n \u003cp\u003eT\u003csub\u003emax\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003eY\u003csub\u003emax\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003eS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e305-DMY\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003eDO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003eLL\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003ea\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e-0.655\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e-0.238\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 59px;\"\u003e\n \u003cp\u003e-0.451\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e0.631\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e-0.582\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e0.652\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e0.092\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e0.105*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003eb\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e0.731\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 59px;\"\u003e\n \u003cp\u003e0.155\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e0.125\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e0.380\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e-0.065\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e-0.197\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e-0.222**\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003ec\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 59px;\"\u003e\n \u003cp\u003e-0.527\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e0.281\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e-0.341\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e-0.083\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e-0.404\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e-0.475**\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003eT\u003csub\u003emax\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 59px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e-0.241\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e0.957\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e0.051\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e0.346\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e0.417**\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003eY\u003csub\u003emax\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 59px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e-0.219\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e0.903\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e0.000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e0.009\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003eS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 59px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e0.018\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e0.278\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e0.342**\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003e305-dMY\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 59px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e0.116\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e0.162**\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 75px;\"\u003e\n \u003cp\u003eDO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 64px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 59px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 57px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e0.934**\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eCorrelation is significant * (P\u0026lt;0.05) ** (P\u0026lt;0.01)\u003c/p\u003e"},{"header":"Discussion","content":"\u003ch2\u003e305-dMY\u003c/h2\u003e\n\u003cp\u003eIn terms of milk yield CS (P\u0026lt;0.05), parity and DO (P\u0026lt;0.01) had a significant effect on 305-dMY (Table 3). Multipar cows\u0026nbsp;produced significantly higher 305-dMY than the primipar cows. Similarly, Atashi (2011); Katok and Yanar (2012); Mik\u0026oacute;n\u0026eacute; J\u0026oacute;n\u0026aacute;s et al. (2016); Kino et al. (2019); Mas\u0026iacute;a et al. (2020); Kramarenko and Kramarenko (2022); Poczynek et al. (2023); Evangelista et al. (2024) reported that primipar cows produced lower 305-dMY than multipars. This result probably related with primipar cows\u0026rsquo; mammary epithelial cells have not complete the development. On the other hand, with parity increase number of the mammary epithelial cells and activity of them increase too (Sorensen et al. 2006). \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAlso, cows calved in winter had more 305-dMY than calved in spring in this study (Table 3). This might be linked with cows that calved spring reach the peak yield on middle of the summer and exposed to heat stress and milk yield decreases. There are lots of study reports that CS had significant effect on 305-dMY but the highest and the lowest 305-dMY were determined in different seasons (Tekerli et al. 2000b; Rekik et al. 2003; Albarr\u0026aacute;n-Portillo and Pollott 2011; M\u0026rsquo;hamdi et al. 2012; Mik\u0026oacute;n\u0026eacute; J\u0026oacute;n\u0026aacute;s et al. 2016; Kino et al. 2019; Poczynek et al. 2023). Wide variation among the seasons may be originated from the differences between climate that cows are breed or management of the herd, maybe taking precautions against adverse weather conditions.\u003c/p\u003e\n\u003cp\u003eIn the study 305-dMY were in after 151\u0026le;\u0026nbsp;d groups, while the lowest 305-dMY determined in 60 d DO group. Similarly, in some studies, reports the service period had a significant effect on 305-dMY (Kino et al. 2019; Abd-El Hamed and Kamel 2021). There was only significant interaction determined between CS and parity (Table 3). Interaction a\u0026ccedil;ıklanmalı\u003c/p\u003e\n\u003ch2\u003eLactation curve traits and persistency\u003c/h2\u003e\n\u003cp\u003eThe effect of parity, CS and DO were presented Table 4. Parity (P\u0026lt;0.001) and DO (P\u0026lt;0,05) showed a significant effect on parameter a.\u0026nbsp;Similarly, Wood (1969); Wood (1970); Shanks et al. (1981); Rekik et al. (2003); Darej et al. (2012); Duque et al. (2018); Awad et al. (2022); Marumo et al. (2022); Innes et al. (2023); Evangelista et al. (2024) reported that parity had a significant effect on parameter a. As in 305-dMY, parameter a that known as initial milk yield of the lactation, primipar cows had lowest value maybe related to underdevelopment mammary epithelial cells. As incompatible with this study Tekerli et al. (2000b) determined any significant effect of days open on ln(a).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eParameter b of the Wood model significantly affected by parity (P\u0026lt;0.05), CS and DO (P\u0026lt;0.001). As seen in the Table 4, primipar cows and cows calved in summer had a flatter incline slope curve before the peak yield. \u0026nbsp;The results of Atashi et al. (2013); Kramarenko and Kramarenko (2022); Innes et al. (2023) in agreement with this study which were reported that parameter b increase with the parity increase. Similarly Atashi et al. (2009) reported that the parameter b the highest in cows calved in winter. The results of Atashi et al. (2013); Kramarenko and Kramarenko (2022); Innes et al. (2023) in agreement with this study which were reported that parameter b increase with the parity increase. Similarly Atashi et al. (2009) reported that the parameter b the highest in cows calved in winter.\u0026nbsp;Also 61-90 DO group has a steeper incline slope curve till the peak production. Similar to this study significant effect of DO on parameter b reported by\u0026nbsp;Tekerli et al. (2000b); Ruban et al. (2022).\u003c/p\u003e\n\u003cp\u003eCS (P\u0026lt;0.01), parity and DO (P\u0026lt;0.001) showed a significant effect on parameter c. As seen Table 4, the parameter c was found to be the highest in multipar cows similar to findings of Darej et al. (2012); Atashi et al. (2013); Innes et al. (2023). Parameter c represents the decline in milk yield after peak yield in lactation curve. This most likely linked with mammary cells are more active in multipar cows\u0026rsquo; and thus milk yield rapidly declines after peak. Also, cows calved in summer had the lowest parameter c value while cows calved in winter had the highest. Atashi et al. (2009) determined the parameter c highest in winter calver cows parallel to our result. This might be related with cows calved in winter reach peak yield early and thus milk yield rapidly declines.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eLactation persistency significantly affected by CS (P\u0026lt;0.05),\u0026nbsp;parity and DO (P\u0026lt;0.001). This may be associated with primipar cows\u0026rsquo; mammary cell renewal are better and have lower somatic cell score, high serum and mammary concentrations of insulin-like growth hormone 1 (IGF-1), which enables mammary glands to proliferate by mitosis, positive correlation between lactation persistency and IGF-1, explain why lactation persistency is higher in the first lactation (Schutz et al. 1990; Weber et al. 2000; Sorensen and Knight 2002; Miller et al. 2006; Webster et al. 2024). Also, cows calved in autumn and winter are more persistent than cows calved in summer and spring in line with the results of Khalifa et al. (2018); Ruban et al. (2022). Moreover, in some studies the effect of days open on parameter c were reported significant in agreement to this study (Tekerli et al. 2000b; Ruban et al. 2022). In the study, parameter c decreases with the days open increase while lactation persistency increase probably caused by negative affect of pregnancy hormones (Yart et al. 2012; Chen et al. 2024).\u003c/p\u003e\n\u003cp\u003eIn the present study T\u003csub\u003emax\u003c/sub\u003e effected by both parity and DO (P\u0026lt;0.001). Parity (P\u0026lt;0.001), CS and DO (P\u0026lt;0.01) showed a significant effect on Y\u003csub\u003emax\u003c/sub\u003e. Primipar cows reached peak yield slowly and have lower peak yield in line with the results of Chen et al. (2016); Sanad and Gharib (2022); Innes et al. (2023); Evangelista et al. (2024). On the other hand cows calved in winter have highest peak yield similar to findings of Khalifa et al. (2018).\u0026nbsp;\u003c/p\u003e\n\u003ch2\u003ePhenotypic correlations\u003c/h2\u003e\n\u003cp\u003eAs seen in Table 6, a significant negative correlation (-0.655) between parameters a and b indicates that a higher initial milk yield is associated with a slower rate of increase in milk production, resulting in a more gradual progression to peak yield. Also, positive significant correlation (0.731) between parameter b and c indicates that rapidly incline in milk yield at the same time would rapidly decline after peak. High positive correlation (0.957) between T\u003csub\u003emax\u003c/sub\u003e and S; and negative correlation (-0.341) between parameter c and S means that cows which reach later to peak yield and slow decline after peak are more persistent. Contrarily, because of the fact that significant negative correlation between S and Y\u003csub\u003emax\u003c/sub\u003e (-0.219), cows with higher persistency have lower peak yield. According the positive (0.631) and negative (0.582) significant correlations cows that higher initial milk yield have more peak milk yield but lower persistency. In addition, positive significant correlations between 305-dMY and parameter a-Y\u003csub\u003emax\u003c/sub\u003e (0.652; 0.903) indicates that higher initial and peak yield caused higher 305-dMY. These findings in agreement with the reports of Tekerli et al.\u0026nbsp;(2000b); Saghanezhad et al. (2017); Awad et al. (2022); Sanad and Gharib (2022); Zamorano-Algandar et al. (2022). Moreover, positive significant correlation between DO and S-305-dMY (0.278; 0.116) explained that with DO length increase 305-dMY and S increases. As expected, when the DO increase T\u003csub\u003emax\u003c/sub\u003e increase but parameter b and c decreases.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eDairy cows\u0026rsquo; milk yield and lactation curve affected by lots of environmental factors. This study shows that parity, calving season, and days open (DO) have a strong effect on milk yield and lactation traits in Holstein-Friesian cows. Multiparous cows and cows that calve in winter produced higher milk yields over 305 days, while primiparous cows, though yielding less, maintained milk production for a longer time. Seasonal differences were also observed, with cows calving in autumn and winter reaching higher peak milk production and having better persistency. Additionally, the length of the days open period was crucial, as cows with 151\u0026ndash;180 days open achieved the best results, while shorter intervals (\u0026le;\u0026thinsp;60 days) led to lower production and persistency.\u003c/p\u003e \u003cp\u003eThese findings underline the importance of tailoring herd management strategies by considering parity, calving season, and days open to improve milk yield and efficiency. By using these insights, dairy farmers can make practical adjustments that lead to higher productivity, sustainable practices, and stronger economic outcomes in the dairy industry.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cspan\u003eThe experimental procedure has been accepted by Ethics Committee of Selcuk University Faculty of Veterinary Experimental Animals Production and Research Centre (Permit No.2020/91, date of approval: 27.10.2020).\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eAcknowledgements\u0026nbsp;\u003c/strong\u003eThis study was derived from corresponding author\u0026apos;s Phd Thesis accepted in 2023 by \u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;... Thanks to \u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;. authority for sharing the farms\u0026apos; data.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e Serdar G\u0026uuml;ler conceptualization, data collection and curation, perform analysis, writing first draft of the manuscript were performed by Serdar G\u0026uuml;ler; data collecting permission from enterprise and supervision of the study, review and editing the manuscript performed by Ali Akmaz. Final manuscript read and agreed by both authors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability Statement\u0026nbsp;\u003c/strong\u003eThe datasets generated and analyzed during this study are available from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003eThe authors did not report any financial support.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u0026nbsp;\u003c/strong\u003eThe authors declare no competing interests\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical statement\u0026nbsp;\u003c/strong\u003eThe experimental procedure has been accepted by Ethics Committee of \u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAbd-El Hamed AM, Kamel ER (2021) Effect of some non-genetic factors on the productivity and profitability of Holstein Friesian dairy cows. 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Trop Anim Health Prod 54(2): 88. https://doi.org/10.1007/s11250-022-03098-7\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Calving season, Days open, Lactation curve, Persistency of lactation, Milk production","lastPublishedDoi":"10.21203/rs.3.rs-6440916/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6440916/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study investigates the influence of parity, calving season (CS), and days open (DO) on milk yield and lactation traits in Holstein-Friesian cows. A total of 5171 test-day milk yield records collected from 307 cows were analyzed using the Wood equation with non-linear regression. The findings reveal significant effects of these factors on 305-day milk yield (305-dMY), lactation curve parameters (a, b, c), peak milk yield (Y\u003csub\u003emax\u003c/sub\u003e), time to peak yield (T\u003csub\u003emax\u003c/sub\u003e), and lactation persistency (S). Multiparous cows and those calving in winter produced notably higher 305-dMY compared to primiparous cows and cows calving in other seasons. While primiparous cows demonstrated lower initial and peak milk yields and took longer to reach peak yield, they exhibited stronger lactation persistency. Seasonal variations also impacted lactation performance, with autumn and winter calving associated with higher peak milk yield (Y\u003csub\u003emax\u003c/sub\u003e) and improved persistency. Days open (DO) played a crucial role in shaping lactation traits, as cows with 151\u0026ndash;180 days open achieved the highest peak yield and lactation persistency, while those with \u0026le;\u0026thinsp;60 DO exhibited significantly lower persistency and milk yield across all traits. These findings highlight the importance of integrating parity, calving timing, and DO management into strategic herd management practices. Optimizing these factors can substantially improve milk production, lactation performance, and overall farm efficiency, offering actionable insights for sustainable dairy farming. This study reinforces the need for evidence-based approaches to enhance productivity and support long-term dairy industry growth.\u003c/p\u003e","manuscriptTitle":"Evaluating Lactation Persistency, Lactation Curve Parameters, and Dairy Efficiency: The Role of Parity, Calving Season, and Days Open in Holstein-Friesian Cows","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-04-16 07:19:54","doi":"10.21203/rs.3.rs-6440916/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"050854a5-1724-4376-91ee-9970b3f7826a","owner":[],"postedDate":"April 16th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-04-23T15:23:37+00:00","versionOfRecord":[],"versionCreatedAt":"2025-04-16 07:19:54","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6440916","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6440916","identity":"rs-6440916","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}