Effect of seropositivity to bovine leukosis virus, bovine viral diarrhea and neosporosis on productive and reproductive indices in dairy herds

Effect of seropositivity to bovine leukosis virus, bovine viral diarrhea and neosporosis on productive and reproductive indices in dairy herds | 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 Short Report Effect of seropositivity to bovine leukosis virus, bovine viral diarrhea and neosporosis on productive and reproductive indices in dairy herds Cristian C. Rúa-Giraldo, Albeiro López-Herrera, Z.Tatiana Ruiz-Cortés This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8232906/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 The objective was to compare seropositive and seronegative animals to bovine leukosis virus (BLV), bovine viral diarrhea (BVD) and Neospora canis (Nc) in seven productive characteristics (adjusted milk production (PDNa), percentage of adjusted protein (PPa), kilograms of adjusted protein (KgPROa), percentage of adjusted fat (PFa), kilograms of adjusted fat (KgFa), somatic cell score (SCS), all adjusted to 305 days, and duration of lactation (DurL)), and in six reproductive characteristics (age at first service of heifers (AgeFSh), services per conception in heifers (SCh), services per conception in cows (SC), age at parturition (AgeP), days open (DO) and calving interval (CI)). The presence of BLV resulted in low levels for KgPROa, KgFa, and high CI in infected cows. For AgeP, SCh and SC there was no effect of BLV seropositivity. It was a tendency of BLV to affect negatively AgeFSh, PDNa, DO, and SCS. Nc presence had negative effect on SC. A tendency to present a negative effect by DVB was found for PDNa; a significant effect of the interaction between DVB-Nc pathogens on PFa was found, and a tendency to present a negative effect of the interaction between DVB-Nc on KgFa and between BLV-DVB on CI. Antibodies Dairy Herds pathogens Epidemiology Milk production Introduction The specialized bovine milk production systems located in the high tropic regions of the department of Antioquia (Colombia) constitute a sector of great relevance in the economy, directly and indirectly. Therefore, strategies must constantly be sought that favor the progress of this livestock sector, and thus, of the producers and families that depend on this activity. Enzootic bovine leukosis (EBL) is a disease of high morbidity and low mortality, caused by infection with the bovine leukosis virus (BLV) (De la Sota, 2004 ), which result in a latent infection throughout the life of the animal. EBL mainly affects cattle, especially those dedicated to milk production, attacks their immune system by infecting B lymphocytes and generating persistent lymphocytosis (PL). It produces immunosuppression and economic losses derived from a decrease in milk production compared to negative animals. Furthermore, it is estimated that the reduction in the immune response capacity allows the entrance of other pathogenic agents that can cause reproductive problems in the herd, such as bovine viral diarrhea (BVD) and Neospora canis (Nc). They infect cattle and cause health problems that will negatively affect production and reproduction in animals. All of the above makes EBL a concern for producers in Colombia, which currently does not have an official diagnosis and control system. Due to this and to the absence of treatments or vaccines to prevent and control the negative effects of BLV and the latency of the virus, permanent negative effects can be generated on the productive and reproductive parameters of the animals, generating over time of time, greater economic losses per animal and, impact on the productive system (De la Sota, 2004 ; Ortega et al. 2016 ). The objective of the present study was to determine the effect of infection by BLV, BVD and Nc on the productive and reproductive parameters in a population of specialized dairy cows in the high tropics of the department of Antioquia, Colombia, South America. Materials and Methods Animals The target population was made up of 224,714 milking cows from a specialized dairy in the Valle de Aburrá, North and East regions of Antioquia. The sample size was calculated with an expected prevalence of 44% reported in a recent study carried out in the department of Antioquia (Úsuga-Monroy et al. 2018 ), a confidence level of 95%, a relative error of 10% (that is, an absolute error of 4.4%) and a design effect of 1.2, yielding a sample size (n) of 599 cows of various breeds and crosses ranging from 0 months of age to 14 years old. Animals were sampled in 16 municipalities, 3 from the Valle de Aburrá region, 7 from the Northern region, and 6 from the Eastern region. Convenience sampling was carried out in the dairy herds of the three regions. The samples were distributed in 53 herds as follows: 33 herds located in the North region, 10 herds in the Eastern region and 10 herds located in the Valle de Aburrá. The number of herds per region was not taken as a determining factor, but herds belonging to a milk control program from a colombian dairy collection and processing company called Colanta were included. The herds considered were those with good records of productive and reproductive information, which signed informed consent to participate in the project. More herds from the Northern region were included in the sampling, since it is the largest milk producer region in the department of Antioquia. Management, feeding and health were variable and depended on each herd. A proportional number of samples was taken in each farm, depending on the bovine population identified prior to sampling and were randomly selected. The following breeds were included in the sampling: JER: Jersey (n = 40), HO: Holstein (n = 191), RS: Swedish Red (n = 17), BSHO: Brown Swiss x Holstein (n = 4), JH: Jersey x Holstein (111), RSH: Swedish Red x Holstein (n = 6), AYR: Ayrshire (n = 9), AYRHO: Ayrshire x Holstein (n = 4), BS: Swiss Brown (n = 4), UN: Unidentified breed (n = 197), and others: Creollo breed BON-Blanco Orejinegro- x Holstein, Normand x Holstein, Angus x Holstein, Swedish Red x Jersey, Cebu Gyr x Normand (n = 16). In this way, the sampling unit constituted a representative value of the information found in the specialized dairy of Antioquia. Blood sampling and processing Blood sampling was performed from the middle coccygeal vein, centrifuged at 3000 rpm for 10 minutes and the plasma and serum were stored at -20ºC until analysis. The serological diagnosis of positivity to the three pathogens evaluated was made by the Enzyme-Linked Immunoassay (ELISA) test following the recommendations of the manufacturers of the diagnostic kits: for the analysis of seropositivity to BLV, the Svanovir, Svanova kit® was used; for Nc the IDEXX Neospora X2 kit and for BVD the commercial IDEXX BVDV p80 Ab kit. The latter two from the manufacturer IDEXX®. Determination of productive and reproductive parameters The productive characteristics evaluated were: adjusted milk production (PDNa), adjusted protein percentage (PPa), kilograms of adjusted protein (KgPROa), adjusted fat percentage (PFa), kilograms of fat per adjusted lactation (KgFa), adjusted somatic cell score (SCS), all adjusted to 305 days, and duration of lactation (DurL). The reproductive characteristics evaluated in this research were: age at first service in heifers (AgeFSh), services per heifer conception (SCh), calving interval (CI) measured as the number of days that elapsed between two consecutive calvings, number of services per conception of cows (SC) measured as the number of inseminations that were carried out until pregnancy detection and open days (DO) measured as the days that elapsed from calving to conception. Biologically reliable ranges of the characteristics were used as follows: DurL, data from 200 to 400 days were used; for PDNa, values from 3000 to 7500 kg of milk were accepted; for PPa values from 2% to 5% were included; for PFa values from 2.5% to 6%; for CI values from 300 to 540 days were analyzed; for DO, values from 30 to 260 days were studied. A logarithmic transformation of the characteristic somatic cell count (SCC) was per-formed to obtain the SCS, where SCS=(Log2 (SCC/100000) + 3) (Rodriguez et al. 2000 ). Statistical analysis The average for each characteristic in the population was determined, using the data during complete lactation and the means of each characteristic were established for the animals positive and negative for BLV, BVD or Nc. For the association analysis, a generalized linear model was used with a significance level of 0.05%; in addition, the odds ratios (OR) were calculated, which allows to define the degree or variability (percentage) in the values of the productive parameters and /or reproductive depending on whether or not they are positive for each pathogen (BLV, BVD or Nc). Variables with OR > 1 and p value < 0.05 were considered factors whose average is lower due to infection, while those with OR < 1 and p < 0.05 were factors whose average is higher due to infection. OR of 1 indicates that there is no positive or negative association between the variable and BLV, BVD or Nc infection (Norton et al. 2018 ). The R i386 4.2.0 and Jamovi 2.3.5 statistical packages were used and significance was assumed when p < 0.05. Results The 599 animals evaluated were distributed in 16 municipalities of the department of Antioquia. The total serological prevalence was 41.13% of infection for BLV, 28.48% of infection for Nc and 22.7% for BVD in the evaluated population. Of these 599 cows, 1363 lactations were used to make the association of productive and reproductive characteristics with BLV, BVD and Nc infection. The general averages for KgPROa and KgFa found were 117.1 + 29.5 and 215.1 + 37.1, respectively. Both parameters increased as the number of lactations increased until lactation 5 and then these parameters decreased for the L6 + group (Table 1 ). The SCS presented a gradual increase from the first lactation until reaching L6 or more, where a general average value of 3.62 was found for the specialized dairy in Antioquia (Table 1 ). Table 1 Evaluation of compositional parameters and sanitary quality in 53 specialized dairy herds in the high tropics of the department of Antioquia-Colombia, South America Lactation KgPROa KgFa SCS A SD N A SD N A SD N L1 163 28.9 1471 192 32.7 1472 3.2 1.4 664 L2 178 30.2 949 215 36.9 938 3.4 1.5 646 L3 187 28.9 718 230 38 711 3.6 1.5 585 L4 190 28.6 561 236 40.5 546 3.9 1.7 469 L5 190 29.8 394 234 40.6 389 4.1 1.7 369 L6+ 184 31.5 463 230 43.4 428 4.2 1.8 548 G 177.1 29.5 4556 215.1 37.1 4484 3.62 1.6 3281 KgPROa = kilograms of protein by lactation, adjusted to 305 days; KgFa = kilograms of lactation-adjusted fat; SCS = somatic cell score; L = lactation; L6 + = grouping of lactation from 6th parturition; A = average; SD = standard deviation; N = Amount of data in the analysis; G = general average BLV seropositivity was significant (p < 0.05) for KgPROa, KgGRAa, where the average was lower in seropositive cows and for CI (p = 0.05), being significantly higher in positive cows; for AgeP (p = 0.23), SCh (p = 0.33) and SC (p = 0.68) there was no effect of BLV seropositivity. For AgeFSh (p = 0.07), PDN (p = 0.11), DO (p = 0.09), and SCS (p = 0.10) a tendency to present a negative effect by BLV was found (Table 2 ). Table 2 . Results of association analyzes of productive and reproductive variables with Bovine Leukosis Virus (BLV) serodetection (positive and negative cows) in 599 cows in 53 herds from milk production regions in Antioquia-Colombia, South America. Variable P value model R 2 Odds ratio Source of variation P value Average + cows Average -cows PDNa <0 .001 0.10 0.98 BLV 0.10 5500 5633 KgPROa <0 .001 0.12 0.92 BLV 0.01 165.4 * 180 * KgFa <0 .001 0.19 0.89 BLV <0.001 195.1 * 220 * DurL <0 .001 0.06 0.95 BLV 0.14 307 309 SCS <0 .001 0.13 1.09 BLV 0.10 3.78 3.45 AgeFSh <0 .001 0.93 1.01 BLV 0.07 560 534 AgeP <0 .001 1.00 1.03 BLV 0.23 1556 1506 DO <0 .001 0.31 1.12 BLV 0.09 112 110 SCh <0 .001 0.33 1.09 BLV 0.33 1.49 1.36 SC <0 .001 0.03 1.02 BLV 0.68 1.91 1.87 CI <0 .001 0.93 1.01 BLV 0.05 387 * 385 * PDNa: adjusted to 305 days milk production (Kg); KgPROa: protein in kilograms; KgFa: fat in kilograms; DurL: duration of lactation (Days); CS: somatic cell score; AgeFSh: age at first service in heifers; AgeP: age at parturition; DO: days open; SCh: services per conception in heifers; SC: services per conception; CI: calving interval; * Significant data in bold The presence of Nc was significant (p < 0.05) for SC (p = 0.006) and a tendency to present a negative effect by BVD was found for PDNa (p = 0.1). A significant effect of the interaction between BVD-Nc pathogens on Fa (p = 0.03) was found, and a tendency to present a negative effect of the interaction between BVD-Nc on KgFa (p = 0.095) and between BLV-BVD on CI (p = 0.057) was detected. Table 3 depicts the averages in seropositive and seronegative cows of the characteristics that had a significant association with seropositivity to one of the three pathogens or to two of these when they occur in the same animal. Table 3 Analysis of association between productive and reproductive variables and seropositivity to Bovine Leukosis Virus (BLV), bovine viral diarrhea (BVD) and Neospora canis (Nc)(positive and negative cows) and the interactions between these pathogens in 599 cows in 53 herds from dairy production regions in Antioquia-Colombia, South America. Patogenes Parameters Odds ratio P value Average + cows Average - cows DVB PDNa 0.972 0.166 5190 5700 Nc SC 1.35 0.006 2.75 1.29 Nc DurL 0.960 0.142 299 315 BLV CI 1.03 0.052 387 385 BLV KgFa 0.884 0.001 195 220 BLV KgPROa 0.927 0.002 165 180 BLV-BVD PDNa 0.856 0.124 5119 5570 BLV-BVD CI 1.01 0.057 391 382 BVD-Nc Fa 0.864 0.03 3,4 4,5 PDNa: milk production adjusted to 305 days (Kg); SC: services per conception; DurL: duration of lactation (Days); CI: calving interval; KgFa: fat adjusted to 305 days in kilograms; KgPROa: protein adjusted to 305 days in kilograms; Fa: percentage Discussion This study is a pioneer in presenting the relationships between seropositivity for 3 pathogens (BLV, BVD, and Nc) with productive and reproductive variables in specialized dairy systems. Most research that determines the effects of pathogens on production has been carried out with positivity tests for a single pathogen (Arnaiz et al. 2021 ). The present investigation recorded a reduction in the average production of 133 kg of milk per lactation adjusted to 305 days, in BLV seropositive cows, equivalent to 2% (Table 2 ). In cows seropositive to BVD, the reduction in production (PDNa) was equivalent to 3% and in cows that were seropositive at the same time to BLV and Nc it was equivalent to 15% (Table 3 ). This is similar of results reported by Hobson et al. ( 2002 ) in Holstein that presented BVD-related abortions, and decreased in production of about 2%; similar also to seropositive Polish Holstein cows with 4.3% less than in non-infected cows (Norby et al. 2016 ); and to other studies in which Holstein cows presented a 1.1% milk production reduction (p = 0.052) when infected with BLV and a reduction in the average production per lactation adjusted to 305 days in cows infected with BVD, equivalent to 3% (Romero et al. 2014 ; Yue et al. 2021 ). Seropositive-BLV effect on milk production in our study was lower than that found in other studies in which it was a reduction of 10.41% (Nekouei et al. 2016 ), and of 28.14% in animals seropositive to BLV, BVD and Nc (Tiwari et al. 2007 ). In the present study, BLV infection was negatively associated (p = 0.01) with kilograms of protein per lactation, which was lower by 8.1% (Table 2 ). This data is higher than that found in other research, where leukosis-free cows had a higher protein content per lactation compared to seropositive ones (Erskine et al. 2011 ). Our results show that the BLV seropositivity variable was negatively significant for kilograms of fat produced by lactation (p = 0.001), where the amount of fat produced was lower by 11.3% for animals positive to BLV with respect to negative animals (Table 2 ). This data is contrary to that found in another study, where it was determined that positive cows have a higher fat content per lactation (304.1 Kg) than negative cows (302.6 Kg) (Tiwari et al. 2007 ). Modifications and changes that must be activated in order to maintain the defense system against pathogens that lead to a redistribution in the use of energy and nutrients towards defense pathways, directly and immediately affect the compositional quality of milk (Rhodes et al. 2003 ). The reason why BLV-positive animals tend to show lower milk production, compared to negative animals, is probably due to the fact that with the onset of BLV infection there is a decrease in the T cell population and an increase in the number of circulating B lymphocytes; this causes a high endogenous demand for proteins for cell production, which can influence the decreased availability of protein precursors for the metabolic pathways of milk production in the mammary gland. Parameter values tend to improve, but never to the same level as a seronegative animal (Romero et al. 2014 ). Milk quality is not only measured by its protein or fat content, hygienic quality is also very important for the producer payment system in Colombia, for the industry in charge of processing and subsequent milk products marketing and finally for the final consumer health. One measure of hygienic quality is the somatic cell score (SCS), an indicator that serves as a measure of the health of the mammary gland. In the present study, infection with BLV was not significant (p = 0.10) in relation to the effect on SCS, but there is a tendency for positive animals to present a higher somatic cell score, in the order 9% (Table 2 ). This may be due to the fact that when infected with the virus, the mammary gland becomes susceptible to the colonization of microorganisms that cause infectious processes; the presence of antigens triggers an immunological response, in which the galactopoietic tissue undergoes cellular desquamation as a defense mechanism and there is an increased passage of leukocyte cells from the blood to the cistern of the mammary gland, which causes an increase in the SCS (Wu et al. 2003 ). These values agree with what was reported in another study, where the SCS of BLV seropositive cows was 2.51 in contrast to that of seronegative cows of 1.98 (p ≤ 0.05) (Cadavid, 2012 ). On the other hand, another study indicated that infection with BLV significantly increased the SCS (4.8 compared to 3.9) especially in cows that were in mid-lactation and with 4 or more parturitions (Bojarojć-Nosowicz et al. 2006). In the present study, the effect of seropositivity to BLV was not significant (p = 0.07) for AgeFSh, but there is a tendency for animals positive for this virus to take longer to arrive at the first service (26 days longer in positive animals) (Table 2 ). This value agrees with what was reported that seropositive animals needed around 22.97 days more to reach the first service, compared to seronegative animals (Romero et al. 2014 ). The effect of BLV positivity was not significant (p = 0.09) for DO, but there is a tendency for positive animals to have a greater number of days necessary to achieve effective pregnancy, of the order of 1% (Table 3 ). This is related to the fact that BLV positivity had a significant effect (p = 0.05) increasing the CI (Table 2 ). This value is lower than what was reported in Costa Rica where seropositive animals presented wider CI (Romero et al. 2014 ). No effect of BLV seropositivity was found with respect to SC (p = 0.68), where BLV-positive animals presented an average of 1.91 SC, while negative animals presented 1.87 SC (Table 3 ). This coincides with what was reported in a study in dairy cows from Costa Rica, where no significant effect of BLV serological status on the average SC was observed (Romero et al. 2014 ). In the present study, a negative effect of Nc seropositivity on SC (2% increase); Nc-positive animals tend to present early fetal death with repetition of heat, abortion in the middle third of gestation, perinatal or neonatal death, and cases of infertility, all these resulting in the increase of the SC to reach a pregnancy (Moore et al. 2005 ). Some significant interactions were found between seropositivity for two pathogens and effect on productive and/or reproductive indices. Furthermore, a trend towards significant interaction was found in some cases for two pathogens, and in no case was any trend or significant interactions found between seropositivity to 3 pathogens in terms of their effects on the productive and/or reproductive variables. Taking together, it can be concluded that the BLV infection has a negative effect on milk production, since seropositive animals produce less milk per lactation than non-infected animals. Kilograms of fat and protein per lactation are also negatively affected, with productions lower Kg, respectively, compared to animals negative for this pathogen. The sanitary quality of the milk in BLV-positive animals is also diminished, presenting SCS values in their milk that are higher than those in negative animals. The seropositivity of animals against BLV fluctuates with age, since there was a progressive increase in positivity with age, reaching its highest value in animals with 6 or more parturitions. The negative effects found of BLV infection on productive and reproductive parameters are greater as the age of the animal increases. In the herds included in our study, BVD seropositivity had a small detrimental effect on milk production, as well as a negative trend on the CI when there is an interaction with BLV. Also, positivity to Nc had a negative effect on the number of effective services, directly causing an increase in the CI. Declarations Acknowledgments The authors would like to thank the Colombia Consortium: this research was funded by the Universidad de Antioquia (https://www. udea.edu.co), the Universidad Nacional de Colombia (https://unal.edu. co), the Government of Antioquia (https://www.antioquia.gov.co), the Universidad Pontificia Bolivariana and COLANTA dairy cooperative through the CONVOCATORIA CONJUNTA DE PROYECTOS EN EL MARCO DE LA AGENDA REGIONAL DE I + D of 2020. The funder was not involved in the study design, data collection and analysis, publication decisions, or manuscript preparation. Statement of Animal Ethics All animal experiments followed the CCAC Guidelines on the care and use of farm animals in research and were approved by the Committee for the Care and Use of Animals-CICUA of the Universidad Nacional de Colombia, Medellín campus (CICUA-020-2020, August 28 th 2020). All procedures were carried out in accordance with relevant regulations and best practices for the care and use of farm animals. Conflicts of interest statement All the authors, we disclose any actual or potential conflicts of interest that could affect our ability to objectively present or review research or data. Funding This work was supported by the Universidad de Antioquia, the Universidad Nacional de Colombia-UN, the Government of Antioquia-Colombia, the Universidad Pontificia Bolivariana and COLANTA dairy cooperative through the CONVOCATORIA CONJUNTA DE PROYECTOS EN EL MARCO DE LA AGENDA REGIONAL DE I + D of 2020, UN Hermes grant number 50166. Competing Interests The authors declare that they have no conflict of interest Authors Contributions All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Rúa-Giraldo, López-Herrera and Ruiz-Cortés. The first draft of the manuscript was written by Rúa-Giraldo and Ruiz-Cortés and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. Data availability The raw data supporting the conclusions of this article will be made available by the authors upon reasonable request. Ethics approval This study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the Committee for the Care and Use of Animals-CICUA of the Universidad Nacional de Colombia (28 th of August 2020, No. CICUA-020-2020). Consent to participate Not applicable. This study did not involve human participants, and therefore no consent to participate was required. Consent to publish Not applicable. This study did not involve any individual person’s data in any form (including images or videos), and thus no consent to publish was required. References Arnaiz I, Cerviño M, Martínez S, Fouz R and Diéguez FJ (2021) Bovine viral diarrhea virus (BVDV) infection: Effect on reproductive performance and milk yield in dairy herds. Vet J. 277:105747. doi: 10.1016/j.tvjl.2021.105747. Bojarojc-Nosowicz B and Kaczmarczyk E (2006) Somatic cell count and chemical composition of milk in naturally BLV-infected cows with different phenotypes of blood leukocyte acid phosphatase. Archives Animal Breeding Tierzucht. 49: 17-28. https://doi.org/10.5194/aab-49-17-2006. Cadavid L (2012) Impacto del virus de la leucosis bovina en la producción de leche, Tesis Maestría en Ciencias Agrarias, Valle del Cauca, Universidad Nacional de Colombia, Palmira, Colombia; pp. 67-75. https://repositorio.unal.edu.co/bitstream/handle/unal/11772/lascarioartemocadavidgutierrez.2012.pdf?sequence=1&isAllowed=y. De la Sota, MD (2004) Manual de procedimientos leucosis bovina enzoótica, Dirección Nacional de Sanidad y Calidad Agroalimentaria. Buenos Aires, SENASA, 34p. http://www.intranet.senasa.gov.ar/intranet/imagenes/archivos/dnsa/manuales_de_procedimiento/09%20Leucosis.pdf. Erskine R, Bartlett P, Sabo K and Sordillo L (2011) Bovine leukemia virus infection in dairy cattle: Effecton serological response to immunization against J5 Escherichia coli bacterin. J. Vet. Med. 3: 915-747. doi: 10.4061/2011/915747. Hobson J, Duffield T, Kelton D, Lissemore K, Hietala S and Leslie K (2002) Neospora caninum serostatus and milk production in Holstein cattle. JAVMA. 221: 1160-1164. https://doi.org/10.2460/javma.2002.221.1160. Moore D, Odeón A, Venturini M and Campero C (2005) Neosporosis bovina. General concepts, immunity and perspectives for vaccination. Rev Argent Microbiol. 37: 217-228. http://www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S0325-75412005000400011&lng=es. Nekouei O, VanLeeuwen J, Stryhn H, Kelton D and Keefe G (2016). Lifetime effects of infection with bovine leukemia virus on longevity and milk production of dairy cows. Prev Vet Med. 133:1-9. doi: 10.1016/j.prevetmed.2016.09.011. Norby B, Bartlett PC, Byrem TM and Erskine RJ (2016) Effect of infection with bovine leukemia virus on milk production in Michigan dairy cows. J. Dairy Sci. 99: 2043-2052. doi: 10.3168/jds.2015-10089. Norton EC, Dowd BE and Maciejewski ML (2018) Odds Ratios—Current Best Practice and Use. JAMA. 320: 84–85. https://doi.org/10.1001/JAMA.2018.6971. Ortega D, Sánchez A, Tobón J, Chaparro Y, Cortés S and Gutiérrez M (2016) Seroprevalence and risk factors associated with bovine leukemia virus in Colombia. J. Vet. Med. Anim. Health. 8:35-43. doi: 10.5897/JVMAH2016.0457. Rhodes JK, Pelzer KD and Johnson YJ (2003) Economic implications of bovine leukemia virus infection in mid-Atlantic dairy herds. JAVMA. 3: 34-52. doi:10.2460/javma.2003.223.346. Rodriguez S, Gianola D and Shook G (2000) Evaluation of models for somatic cell score lactation patterns in Holsteins. Livest. Prod. Sci. 67: 19–30. doi: 10.1016/s0301-6226(00)00193-7. Romero JJ, Dávila G, Beita G and Dolz G (2014) Effect of serological status of the Bovine Leucosis Virus (BLV) on milk production of dairy herds in Costa Rica. Agron. Costarricense. 30: 43-55. https://www.revistas.una.ac.cr/index.php/veterinaria/article/view/6324. Tiwari A, Vanleeuwen JA, Dohoo IR, Keefe GP, Haddad JP, Tremblay R, Scott HM and Whiting T (2007) Production effects of pathogens causing bovine leukosis, bovine viral diarrhea, paratuberculosis, and neosporosis. J. Dairy Sci. 90: 659-69. doi: 10.3168/jds.S0022-0302(07)71548-5. Úsuga-Monroy C, Echeverri J and López A (2018) Presencia de los genotipos 1 y 3 del virus de la leucemia bovina en Antioquia, Colombia. Rev. U.D.C.A Act. y Div. Cient. 21:119-126. https://doi.org/10.31910/rudca.v21.n1.2018.670. Wu D, Murakami K, Morooka A, Jin H and Sentsui H (2003) In vivo transcription of bovine leukemia virus and bovine immunodeficiency-like virus. Virus Res.2: 81-87. doi: 10.1016/s0168-1702(03)00222-3. Yue X, Steeneveld W, Van der Voort M, Van Schaik G, Vernooij J, Van Duijn L, Veldhuis A and Hogeveen H (2021) The effect of bovine viral diarrhea virus introduction on milk production of Dutch dairy herds. J. Dairy Sci. 104:2074-2086. doi: 10.3168/jds.2020-18866. 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. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8232906","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Short Report","associatedPublications":[],"authors":[{"id":554784134,"identity":"66235a22-c24c-4a8b-ac61-5046003d5e76","order_by":0,"name":"Cristian C. Rúa-Giraldo","email":"","orcid":"","institution":"Cooperative University of Colombia","correspondingAuthor":false,"prefix":"","firstName":"Cristian","middleName":"C.","lastName":"Rúa-Giraldo","suffix":""},{"id":554784137,"identity":"e798e253-3d36-4988-b402-a36484b40e9b","order_by":1,"name":"Albeiro López-Herrera","email":"","orcid":"","institution":"National University of Colombia","correspondingAuthor":false,"prefix":"","firstName":"Albeiro","middleName":"","lastName":"López-Herrera","suffix":""},{"id":554784139,"identity":"f61aa7aa-ee9f-487b-ab57-69333025657a","order_by":2,"name":"Z.Tatiana Ruiz-Cortés","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA7UlEQVRIiWNgGAWjYFAC5gYwxcbAfICBB8xMIKSFEaaFLYFELQwMPAbEaZGfkdi64QfDvcQ+/jPfJN5U2DHws+cYMPyowGPHjMS2mz0MxYltDGe3Sc45k8wg2fPGgLHnDG4tzBKJbTd4GBIS2xh7t0nztjEzGNzIMWBmbMOthQ2o5eYfkBZmnmfSvP/qGewJaeEBarkNtoWNh02at+Ewg4EEAS0SPA/bbssYJBi38bAZW845dpxH4syzgoP4/CLfnnzs5puKBNn5/Ycf3nhTUy3H35688QG+EIMAAySXgogDhDSMglEwCkbBKMAPAKwmSidiuybcAAAAAElFTkSuQmCC","orcid":"","institution":"University of Antioquia","correspondingAuthor":true,"prefix":"","firstName":"Z.Tatiana","middleName":"","lastName":"Ruiz-Cortés","suffix":""}],"badges":[],"createdAt":"2025-11-28 19:23:16","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8232906/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8232906/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":97420909,"identity":"548a244e-5334-449a-bee6-49751adcacb6","added_by":"auto","created_at":"2025-12-04 08:28:40","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":49861,"visible":true,"origin":"","legend":"","description":"","filename":"BReportBovineLeukosisBVDNeosporosisDairy.docx","url":"https://assets-eu.researchsquare.com/files/rs-8232906/v1/78ff83888c8a1af275388f77.docx"},{"id":97420910,"identity":"ea3e857a-6516-406a-ab74-2956611d53fc","added_by":"auto","created_at":"2025-12-04 08:28:40","extension":"json","order_by":1,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":4986,"visible":true,"origin":"","legend":"","description":"","filename":"ed1b4efafc474c44b8484f1c4e4513c4.json","url":"https://assets-eu.researchsquare.com/files/rs-8232906/v1/b18c577cbeab2b9ae163fc3f.json"},{"id":97666974,"identity":"09e1ebef-5495-48ba-8abf-185334cd9972","added_by":"auto","created_at":"2025-12-08 09:22:33","extension":"xml","order_by":2,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":82659,"visible":true,"origin":"","legend":"","description":"","filename":"ed1b4efafc474c44b8484f1c4e4513c41enriched.xml","url":"https://assets-eu.researchsquare.com/files/rs-8232906/v1/facd1761c9e5042efaabde19.xml"},{"id":97420912,"identity":"1cd1fc78-a4f0-4cb4-9df3-23117ea7548c","added_by":"auto","created_at":"2025-12-04 08:28:40","extension":"xml","order_by":3,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":82190,"visible":true,"origin":"","legend":"","description":"","filename":"ed1b4efafc474c44b8484f1c4e4513c41structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8232906/v1/fa9e6827828be32d348fcff9.xml"},{"id":97420911,"identity":"539815ee-3d80-4bd7-88e1-fc6bc3e794f5","added_by":"auto","created_at":"2025-12-04 08:28:40","extension":"html","order_by":4,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":85560,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8232906/v1/7cf86caf368e36463ec7714a.html"},{"id":98776055,"identity":"f3c46630-7906-49b4-bca4-f9aad1e703e6","added_by":"auto","created_at":"2025-12-22 12:21:54","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":734770,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8232906/v1/2b778cc7-8388-4c2a-abe6-bacb6ea9c192.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Effect of seropositivity to bovine leukosis virus, bovine viral diarrhea and neosporosis on productive and reproductive indices in dairy herds","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe specialized bovine milk production systems located in the high tropic regions of the department of Antioquia (Colombia) constitute a sector of great relevance in the economy, directly and indirectly. Therefore, strategies must constantly be sought that favor the progress of this livestock sector, and thus, of the producers and families that depend on this activity. Enzootic bovine leukosis (EBL) is a disease of high morbidity and low mortality, caused by infection with the bovine leukosis virus (BLV) (De la Sota, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2004\u003c/span\u003e), which result in a latent infection throughout the life of the animal. EBL mainly affects cattle, especially those dedicated to milk production, attacks their immune system by infecting B lymphocytes and generating persistent lymphocytosis (PL). It produces immunosuppression and economic losses derived from a decrease in milk production compared to negative animals. Furthermore, it is estimated that the reduction in the immune response capacity allows the entrance of other pathogenic agents that can cause reproductive problems in the herd, such as bovine viral diarrhea (BVD) and Neospora canis (Nc). They infect cattle and cause health problems that will negatively affect production and reproduction in animals. All of the above makes EBL a concern for producers in Colombia, which currently does not have an official diagnosis and control system. Due to this and to the absence of treatments or vaccines to prevent and control the negative effects of BLV and the latency of the virus, permanent negative effects can be generated on the productive and reproductive parameters of the animals, generating over time of time, greater economic losses per animal and, impact on the productive system (De la Sota, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2004\u003c/span\u003e; Ortega et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). The objective of the present study was to determine the effect of infection by BLV, BVD and Nc on the productive and reproductive parameters in a population of specialized dairy cows in the high tropics of the department of Antioquia, Colombia, South America.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eAnimals\u003c/h2\u003e\u003cp\u003eThe target population was made up of 224,714 milking cows from a specialized dairy in the Valle de Aburr\u0026aacute;, North and East regions of Antioquia. The sample size was calculated with an expected prevalence of 44% reported in a recent study carried out in the department of Antioquia (\u0026Uacute;suga-Monroy et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), a confidence level of 95%, a relative error of 10% (that is, an absolute error of 4.4%) and a design effect of 1.2, yielding a sample size (n) of 599 cows of various breeds and crosses ranging from 0 months of age to 14 years old. Animals were sampled in 16 municipalities, 3 from the Valle de Aburr\u0026aacute; region, 7 from the Northern region, and 6 from the Eastern region. Convenience sampling was carried out in the dairy herds of the three regions. The samples were distributed in 53 herds as follows: 33 herds located in the North region, 10 herds in the Eastern region and 10 herds located in the Valle de Aburr\u0026aacute;. The number of herds per region was not taken as a determining factor, but herds belonging to a milk control program from a colombian dairy collection and processing company called Colanta were included. The herds considered were those with good records of productive and reproductive information, which signed informed consent to participate in the project. More herds from the Northern region were included in the sampling, since it is the largest milk producer region in the department of Antioquia. Management, feeding and health were variable and depended on each herd. A proportional number of samples was taken in each farm, depending on the bovine population identified prior to sampling and were randomly selected. The following breeds were included in the sampling: JER: Jersey (n\u0026thinsp;=\u0026thinsp;40), HO: Holstein (n\u0026thinsp;=\u0026thinsp;191), RS: Swedish Red (n\u0026thinsp;=\u0026thinsp;17), BSHO: Brown Swiss x Holstein (n\u0026thinsp;=\u0026thinsp;4), JH: Jersey x Holstein (111), RSH: Swedish Red x Holstein (n\u0026thinsp;=\u0026thinsp;6), AYR: Ayrshire (n\u0026thinsp;=\u0026thinsp;9), AYRHO: Ayrshire x Holstein (n\u0026thinsp;=\u0026thinsp;4), BS: Swiss Brown (n\u0026thinsp;=\u0026thinsp;4), UN: Unidentified breed (n\u0026thinsp;=\u0026thinsp;197), and others: Creollo breed BON-Blanco Orejinegro- x Holstein, Normand x Holstein, Angus x Holstein, Swedish Red x Jersey, Cebu Gyr x Normand (n\u0026thinsp;=\u0026thinsp;16). In this way, the sampling unit constituted a representative value of the information found in the specialized dairy of Antioquia.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eBlood sampling and processing\u003c/h3\u003e\n\u003cp\u003eBlood sampling was performed from the middle coccygeal vein, centrifuged at 3000 rpm for 10 minutes and the plasma and serum were stored at -20\u0026ordm;C until analysis. The serological diagnosis of positivity to the three pathogens evaluated was made by the Enzyme-Linked Immunoassay (ELISA) test following the recommendations of the manufacturers of the diagnostic kits: for the analysis of seropositivity to BLV, the Svanovir, Svanova kit\u0026reg; was used; for Nc the IDEXX Neospora X2 kit and for BVD the commercial IDEXX BVDV p80 Ab kit. The latter two from the manufacturer IDEXX\u0026reg;.\u003c/p\u003e\n\u003ch3\u003eDetermination of productive and reproductive parameters\u003c/h3\u003e\n\u003cp\u003eThe productive characteristics evaluated were: adjusted milk production (PDNa), adjusted protein percentage (PPa), kilograms of adjusted protein (KgPROa), adjusted fat percentage (PFa), kilograms of fat per adjusted lactation (KgFa), adjusted somatic cell score (SCS), all adjusted to 305 days, and duration of lactation (DurL).\u003c/p\u003e\u003cp\u003eThe reproductive characteristics evaluated in this research were: age at first service in heifers (AgeFSh), services per heifer conception (SCh), calving interval (CI) measured as the number of days that elapsed between two consecutive calvings, number of services per conception of cows (SC) measured as the number of inseminations that were carried out until pregnancy detection and open days (DO) measured as the days that elapsed from calving to conception.\u003c/p\u003e\u003cp\u003eBiologically reliable ranges of the characteristics were used as follows: DurL, data from 200 to 400 days were used; for PDNa, values from 3000 to 7500 kg of milk were accepted; for PPa values from 2% to 5% were included; for PFa values from 2.5% to 6%; for CI values from 300 to 540 days were analyzed; for DO, values from 30 to 260 days were studied.\u003c/p\u003e\u003cp\u003eA logarithmic transformation of the characteristic somatic cell count (SCC) was per-formed to obtain the SCS, where SCS=(Log2 (SCC/100000)\u0026thinsp;+\u0026thinsp;3) (Rodriguez et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2000\u003c/span\u003e).\u003c/p\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003eStatistical analysis\u003c/h2\u003e\u003cp\u003eThe average for each characteristic in the population was determined, using the data during complete lactation and the means of each characteristic were established for the animals positive and negative for BLV, BVD or Nc. For the association analysis, a generalized linear model was used with a significance level of 0.05%; in addition, the odds ratios (OR) were calculated, which allows to define the degree or variability (percentage) in the values of the productive parameters and /or reproductive depending on whether or not they are positive for each pathogen (BLV, BVD or Nc). Variables with OR\u0026thinsp;\u0026gt;\u0026thinsp;1 and p value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 were considered factors whose average is lower due to infection, while those with OR\u0026thinsp;\u0026lt;\u0026thinsp;1 and p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 were factors whose average is higher due to infection. OR of 1 indicates that there is no positive or negative association between the variable and BLV, BVD or Nc infection (Norton et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). The R i386 4.2.0 and Jamovi 2.3.5 statistical packages were used and significance was assumed when p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eThe 599 animals evaluated were distributed in 16 municipalities of the department of Antioquia. The total serological prevalence was 41.13% of infection for BLV, 28.48% of infection for Nc and 22.7% for BVD in the evaluated population. Of these 599 cows, 1363 lactations were used to make the association of productive and reproductive characteristics with BLV, BVD and Nc infection.\u003c/p\u003e\u003cp\u003eThe general averages for KgPROa and KgFa found were 117.1\u0026thinsp;+\u0026thinsp;29.5 and 215.1\u0026thinsp;+\u0026thinsp;37.1, respectively. Both parameters increased as the number of lactations increased until lactation 5 and then these parameters decreased for the L6\u0026thinsp;+\u0026thinsp;group (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The SCS presented a gradual increase from the first lactation until reaching L6 or more, where a general average value of 3.62 was found for the specialized dairy in Antioquia (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eEvaluation of compositional parameters and sanitary quality in 53 specialized dairy herds in the high tropics of the department of Antioquia-Colombia, South America\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"10\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eLactation\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e\u003cp\u003eKgPROa\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e\u003cp\u003eKgFa\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c10\" namest=\"c8\"\u003e\u003cp\u003eSCS\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eA\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSD\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eN\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eA\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eSD\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eN\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eA\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eSD\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003eN\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eL1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e163\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e28.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1471\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e192\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e32.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e1472\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e3.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e1.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e664\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eL2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e178\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e30.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e949\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e215\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e36.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e938\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e3.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e1.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e646\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eL3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e187\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e28.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e718\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e230\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e38\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e711\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e3.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e1.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e585\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eL4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e190\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e28.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e561\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e236\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e40.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e546\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e3.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e1.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e469\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eL5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e190\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e29.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e394\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e234\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e40.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e389\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e4.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e1.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e369\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eL6+\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e184\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e31.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e463\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e230\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e43.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e428\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e4.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e1.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e548\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eG\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e177.1\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003e29.5\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e4556\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e215.1\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e37.1\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003e4484\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e\u003cb\u003e3.62\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e\u003cb\u003e1.6\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e\u003cb\u003e3281\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"10\"\u003eKgPROa\u0026thinsp;=\u0026thinsp;kilograms of protein by lactation, adjusted to 305 days; KgFa\u0026thinsp;=\u0026thinsp;kilograms of lactation-adjusted fat;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"10\"\u003eSCS\u0026thinsp;=\u0026thinsp;somatic cell score; L\u0026thinsp;=\u0026thinsp;lactation; L6\u0026thinsp;+\u0026thinsp;=\u0026thinsp;grouping of lactation from 6th parturition; A\u0026thinsp;=\u0026thinsp;average; SD\u0026thinsp;=\u0026thinsp;standard deviation; N\u0026thinsp;=\u0026thinsp;Amount of data in the analysis; G\u0026thinsp;=\u0026thinsp;general average\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eBLV seropositivity was significant (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) for KgPROa, KgGRAa, where the average was lower in seropositive cows and for CI (p\u0026thinsp;=\u0026thinsp;0.05), being significantly higher in positive cows; for AgeP (p\u0026thinsp;=\u0026thinsp;0.23), SCh (p\u0026thinsp;=\u0026thinsp;0.33) and SC (p\u0026thinsp;=\u0026thinsp;0.68) there was no effect of BLV seropositivity. For AgeFSh (p\u0026thinsp;=\u0026thinsp;0.07), PDN (p\u0026thinsp;=\u0026thinsp;0.11), DO (p\u0026thinsp;=\u0026thinsp;0.09), and SCS (p\u0026thinsp;=\u0026thinsp;0.10) a tendency to present a negative effect by BLV was found (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eTable 2\u003c/strong\u003e. Results of association analyzes of productive and reproductive variables with Bovine Leukosis Virus (BLV) serodetection (positive and negative cows) in 599 cows in 53 herds from milk production regions in Antioquia-Colombia, South America.\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"563\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eVariable\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP value model\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 50px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eOdds ratio\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSource of variation\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAverage\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;+ cows\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 80px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAverage\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;-cows\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003ePDNa\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e\u0026lt;0\u0026thinsp;.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 50px;\"\u003e\n \u003cp\u003e0.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e0.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003eBLV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e0.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e5500\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 80px;\"\u003e\n \u003cp\u003e5633\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eKgPROa\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e\u0026lt;0\u0026thinsp;.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 50px;\"\u003e\n \u003cp\u003e0.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e0.92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003eBLV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.01\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e165.4\u003csup\u003e*\u003c/sup\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 80px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e180\u003csup\u003e*\u003c/sup\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eKgFa\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e\u0026lt;0\u0026thinsp;.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 50px;\"\u003e\n \u003cp\u003e0.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e0.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003eBLV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026lt;0.001\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e195.1\u003csup\u003e*\u003c/sup\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 80px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e220\u003csup\u003e*\u003c/sup\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003eDurL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e\u0026lt;0\u0026thinsp;.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 50px;\"\u003e\n \u003cp\u003e0.06\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e0.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003eBLV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e0.14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e307\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 80px;\"\u003e\n \u003cp\u003e309\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003eSCS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e\u0026lt;0\u0026thinsp;.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 50px;\"\u003e\n \u003cp\u003e0.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e1.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003eBLV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e0.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e3.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 80px;\"\u003e\n \u003cp\u003e3.45\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003eAgeFSh\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e\u0026lt;0\u0026thinsp;.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 50px;\"\u003e\n \u003cp\u003e0.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e1.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003eBLV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e0.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e560\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 80px;\"\u003e\n \u003cp\u003e534\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003eAgeP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e\u0026lt;0\u0026thinsp;.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 50px;\"\u003e\n \u003cp\u003e1.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e1.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003eBLV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e0.23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e1556\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 80px;\"\u003e\n \u003cp\u003e1506\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003eDO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e\u0026lt;0\u0026thinsp;.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 50px;\"\u003e\n \u003cp\u003e0.31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e1.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003eBLV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e0.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e112\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 80px;\"\u003e\n \u003cp\u003e110\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003eSCh\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e\u0026lt;0\u0026thinsp;.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 50px;\"\u003e\n \u003cp\u003e0.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e1.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003eBLV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e0.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e1.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 80px;\"\u003e\n \u003cp\u003e1.36\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003eSC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e\u0026lt;0\u0026thinsp;.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 50px;\"\u003e\n \u003cp\u003e0.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e1.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003eBLV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e0.68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e1.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 80px;\"\u003e\n \u003cp\u003e1.87\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCI\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e\u0026lt;0\u0026thinsp;.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 50px;\"\u003e\n \u003cp\u003e0.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 59px;\"\u003e\n \u003cp\u003e1.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003eBLV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 64px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.05\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e387\u003csup\u003e*\u003c/sup\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 80px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e385\u003csup\u003e*\u003c/sup\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003ePDNa: adjusted to 305 days milk production (Kg); KgPROa: protein in kilograms; KgFa: fat in kilograms; DurL: duration of lactation (Days); CS: somatic cell score; AgeFSh: age at first service in heifers; AgeP: age at parturition; DO: days open; SCh: services per conception in heifers; SC: services per conception; CI: calving interval; \u003cstrong\u003e\u003csup\u003e*\u003c/sup\u003e\u003c/strong\u003eSignificant data in bold\u003c/p\u003e\u003c/b\u003e\u003cp\u003eThe presence of Nc was significant (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) for SC (p\u0026thinsp;=\u0026thinsp;0.006) and a tendency to present a negative effect by BVD was found for PDNa (p\u0026thinsp;=\u0026thinsp;0.1). A significant effect of the interaction between BVD-Nc pathogens on Fa (p\u0026thinsp;=\u0026thinsp;0.03) was found, and a tendency to present a negative effect of the interaction between BVD-Nc on KgFa (p\u0026thinsp;=\u0026thinsp;0.095) and between BLV-BVD on CI (p\u0026thinsp;=\u0026thinsp;0.057) was detected.\u003c/p\u003e\u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e depicts the averages in seropositive and seronegative cows of the characteristics that had a significant association with seropositivity to one of the three pathogens or to two of these when they occur in the same animal.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eAnalysis of association between productive and reproductive variables and seropositivity to Bovine Leukosis Virus (BLV), bovine viral diarrhea (BVD) and Neospora canis (Nc)(positive and negative cows) and the interactions between these pathogens in 599 cows in 53 herds from dairy production regions in Antioquia-Colombia, South America.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePatogenes\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eParameters\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eOdds ratio\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eP value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eAverage\u003c/p\u003e\u003cp\u003e+ cows\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eAverage\u003c/p\u003e\u003cp\u003e- cows\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDVB\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePDNa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.972\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.166\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e5190\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e5700\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNc\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSC\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1.35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e0.006\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e2.75\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e1.29\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNc\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDurL\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.960\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.142\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e299\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e315\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBLV\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCI\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1.03\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e0.052\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e387\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e385\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBLV\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eKgFa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.884\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e0.001\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e195\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e220\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBLV\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eKgPROa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.927\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e0.002\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e165\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e180\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBLV-BVD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePDNa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.856\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.124\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e5119\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e5570\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBLV-BVD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCI\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1.01\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e0.057\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e391\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e382\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBVD-Nc\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.864\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e0.03\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e3,4\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e4,5\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"6\"\u003ePDNa: milk production adjusted to 305 days (Kg); SC: services per conception; DurL: duration of lactation (Days); CI: calving interval; KgFa: fat adjusted to 305 days in kilograms; KgPROa: protein adjusted to 305 days in kilograms; Fa: percentage\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study is a pioneer in presenting the relationships between seropositivity for 3 pathogens (BLV, BVD, and Nc) with productive and reproductive variables in specialized dairy systems. Most research that determines the effects of pathogens on production has been carried out with positivity tests for a single pathogen (Arnaiz et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe present investigation recorded a reduction in the average production of 133 kg of milk per lactation adjusted to 305 days, in BLV seropositive cows, equivalent to 2% (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). In cows seropositive to BVD, the reduction in production (PDNa) was equivalent to 3% and in cows that were seropositive at the same time to BLV and Nc it was equivalent to 15% (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). This is similar of results reported by Hobson et al. (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2002\u003c/span\u003e) in Holstein that presented BVD-related abortions, and decreased in production of about 2%; similar also to seropositive Polish Holstein cows with 4.3% less than in non-infected cows (Norby et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2016\u003c/span\u003e); and to other studies in which Holstein cows presented a 1.1% milk production reduction (p\u0026thinsp;=\u0026thinsp;0.052) when infected with BLV and a reduction in the average production per lactation adjusted to 305 days in cows infected with BVD, equivalent to 3% (Romero et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Yue et al. \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Seropositive-BLV effect on milk production in our study was lower than that found in other studies in which it was a reduction of 10.41% (Nekouei et al. \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), and of 28.14% in animals seropositive to BLV, BVD and Nc (Tiwari et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2007\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eIn the present study, BLV infection was negatively associated (p\u0026thinsp;=\u0026thinsp;0.01) with kilograms of protein per lactation, which was lower by 8.1% (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). This data is higher than that found in other research, where leukosis-free cows had a higher protein content per lactation compared to seropositive ones (Erskine et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2011\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eOur results show that the BLV seropositivity variable was negatively significant for kilograms of fat produced by lactation (p\u0026thinsp;=\u0026thinsp;0.001), where the amount of fat produced was lower by 11.3% for animals positive to BLV with respect to negative animals (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). This data is contrary to that found in another study, where it was determined that positive cows have a higher fat content per lactation (304.1 Kg) than negative cows (302.6 Kg) (Tiwari et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2007\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eModifications and changes that must be activated in order to maintain the defense system against pathogens that lead to a redistribution in the use of energy and nutrients towards defense pathways, directly and immediately affect the compositional quality of milk (Rhodes et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2003\u003c/span\u003e). The reason why BLV-positive animals tend to show lower milk production, compared to negative animals, is probably due to the fact that with the onset of BLV infection there is a decrease in the T cell population and an increase in the number of circulating B lymphocytes; this causes a high endogenous demand for proteins for cell production, which can influence the decreased availability of protein precursors for the metabolic pathways of milk production in the mammary gland. Parameter values tend to improve, but never to the same level as a seronegative animal (Romero et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2014\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eMilk quality is not only measured by its protein or fat content, hygienic quality is also very important for the producer payment system in Colombia, for the industry in charge of processing and subsequent milk products marketing and finally for the final consumer health. One measure of hygienic quality is the somatic cell score (SCS), an indicator that serves as a measure of the health of the mammary gland. In the present study, infection with BLV was not significant (p\u0026thinsp;=\u0026thinsp;0.10) in relation to the effect on SCS, but there is a tendency for positive animals to present a higher somatic cell score, in the order 9% (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). This may be due to the fact that when infected with the virus, the mammary gland becomes susceptible to the colonization of microorganisms that cause infectious processes; the presence of antigens triggers an immunological response, in which the galactopoietic tissue undergoes cellular desquamation as a defense mechanism and there is an increased passage of leukocyte cells from the blood to the cistern of the mammary gland, which causes an increase in the SCS (Wu et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2003\u003c/span\u003e). These values agree with what was reported in another study, where the SCS of BLV seropositive cows was 2.51 in contrast to that of seronegative cows of 1.98 (p\u0026thinsp;\u0026le;\u0026thinsp;0.05) (Cadavid, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). On the other hand, another study indicated that infection with BLV significantly increased the SCS (4.8 compared to 3.9) especially in cows that were in mid-lactation and with 4 or more parturitions (Bojarojć-Nosowicz et al. 2006).\u003c/p\u003e\u003cp\u003eIn the present study, the effect of seropositivity to BLV was not significant (p\u0026thinsp;=\u0026thinsp;0.07) for AgeFSh, but there is a tendency for animals positive for this virus to take longer to arrive at the first service (26 days longer in positive animals) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). This value agrees with what was reported that seropositive animals needed around 22.97 days more to reach the first service, compared to seronegative animals (Romero et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). The effect of BLV positivity was not significant (p\u0026thinsp;=\u0026thinsp;0.09) for DO, but there is a tendency for positive animals to have a greater number of days necessary to achieve effective pregnancy, of the order of 1% (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). This is related to the fact that BLV positivity had a significant effect (p\u0026thinsp;=\u0026thinsp;0.05) increasing the CI (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). This value is lower than what was reported in Costa Rica where seropositive animals presented wider CI (Romero et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). No effect of BLV seropositivity was found with respect to SC (p\u0026thinsp;=\u0026thinsp;0.68), where BLV-positive animals presented an average of 1.91 SC, while negative animals presented 1.87 SC (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). This coincides with what was reported in a study in dairy cows from Costa Rica, where no significant effect of BLV serological status on the average SC was observed (Romero et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2014\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eIn the present study, a negative effect of Nc seropositivity on SC (2% increase); Nc-positive animals tend to present early fetal death with repetition of heat, abortion in the middle third of gestation, perinatal or neonatal death, and cases of infertility, all these resulting in the increase of the SC to reach a pregnancy (Moore et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2005\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eSome significant interactions were found between seropositivity for two pathogens and effect on productive and/or reproductive indices. Furthermore, a trend towards significant interaction was found in some cases for two pathogens, and in no case was any trend or significant interactions found between seropositivity to 3 pathogens in terms of their effects on the productive and/or reproductive variables.\u003c/p\u003e\u003cp\u003eTaking together, it can be concluded that the BLV infection has a negative effect on milk production, since seropositive animals produce less milk per lactation than non-infected animals. Kilograms of fat and protein per lactation are also negatively affected, with productions lower Kg, respectively, compared to animals negative for this pathogen. The sanitary quality of the milk in BLV-positive animals is also diminished, presenting SCS values in their milk that are higher than those in negative animals. The seropositivity of animals against BLV fluctuates with age, since there was a progressive increase in positivity with age, reaching its highest value in animals with 6 or more parturitions. The negative effects found of BLV infection on productive and reproductive parameters are greater as the age of the animal increases. In the herds included in our study, BVD seropositivity had a small detrimental effect on milk production, as well as a negative trend on the CI when there is an interaction with BLV. Also, positivity to Nc had a negative effect on the number of effective services, directly causing an increase in the CI.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe authors would like to thank the Colombia Consortium: this research was funded by the Universidad de Antioquia (https://www. udea.edu.co), the Universidad Nacional de Colombia (https://unal.edu. co), the Government of Antioquia (https://www.antioquia.gov.co), the Universidad Pontificia Bolivariana and COLANTA dairy cooperative through the CONVOCATORIA CONJUNTA DE PROYECTOS EN EL MARCO DE LA AGENDA REGIONAL DE I + D of \u0026nbsp;2020. \u0026nbsp;The funder was not involved in the study design, data collection and analysis, publication decisions, or manuscript preparation.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatement of Animal Ethics\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll animal experiments followed the CCAC Guidelines on the care and use of farm animals in research and were approved by the Committee for the Care and Use of Animals-CICUA of the Universidad Nacional de Colombia, Medell\u0026iacute;n campus (CICUA-020-2020, August 28\u003csup\u003eth\u003c/sup\u003e 2020). All procedures were carried out in accordance with relevant regulations and best practices for the care and use of farm animals.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflicts of interest statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll the authors, we disclose any actual or potential conflicts of interest that could affect our ability to objectively present or review research or data.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the\u0026nbsp;Universidad de Antioquia, the Universidad Nacional de Colombia-UN, the Government of Antioquia-Colombia, the Universidad Pontificia Bolivariana and COLANTA dairy cooperative through the CONVOCATORIA CONJUNTA DE PROYECTOS EN EL MARCO DE LA AGENDA REGIONAL DE I + D of 2020, UN Hermes grant number 50166. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no conflict of interest\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by R\u0026uacute;a-Giraldo, L\u0026oacute;pez-Herrera and Ruiz-Cort\u0026eacute;s. The first draft of the manuscript was written by R\u0026uacute;a-Giraldo and Ruiz-Cort\u0026eacute;s and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe raw data supporting the conclusions of this article will be made available by the authors upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the Committee for the Care and Use of Animals-CICUA of the Universidad Nacional de Colombia (28\u003csup\u003eth\u003c/sup\u003e of August 2020, No. CICUA-020-2020).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable. This study did not involve human participants, and therefore no consent to participate was required.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to publish\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable. This study did not involve any individual person\u0026rsquo;s data in any form (including images or videos), and thus no consent to publish was required.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eArnaiz I, Cervi\u0026ntilde;o M, Mart\u0026iacute;nez S, Fouz R and Di\u0026eacute;guez FJ (2021) Bovine viral diarrhea virus (BVDV) infection: Effect on reproductive performance and milk yield in dairy herds. Vet J. 277:105747. doi: 10.1016/j.tvjl.2021.105747.\u003c/li\u003e\n\u003cli\u003eBojarojc-Nosowicz B and Kaczmarczyk E (2006) Somatic cell count and chemical composition of milk in naturally BLV-infected cows with different phenotypes of blood leukocyte acid phosphatase. Archives Animal Breeding Tierzucht. 49: 17-28. https://doi.org/10.5194/aab-49-17-2006.\u003c/li\u003e\n\u003cli\u003eCadavid L (2012) Impacto del virus de la leucosis bovina en la producci\u0026oacute;n de leche, Tesis Maestr\u0026iacute;a en Ciencias Agrarias, Valle del Cauca, Universidad Nacional de Colombia, Palmira, Colombia; pp. 67-75. https://repositorio.unal.edu.co/bitstream/handle/unal/11772/lascarioartemocadavidgutierrez.2012.pdf?sequence=1\u0026amp;amp;isAllowed=y.\u003c/li\u003e\n\u003cli\u003eDe la Sota, MD (2004) Manual de procedimientos leucosis bovina enzo\u0026oacute;tica, Direcci\u0026oacute;n Nacional de Sanidad y Calidad Agroalimentaria. Buenos Aires, SENASA, 34p. http://www.intranet.senasa.gov.ar/intranet/imagenes/archivos/dnsa/manuales_de_procedimiento/09%20Leucosis.pdf.\u003c/li\u003e\n\u003cli\u003eErskine R, Bartlett P, Sabo K and Sordillo L (2011) Bovine leukemia virus infection in dairy cattle: Effecton serological response to immunization against J5 Escherichia coli bacterin. J. Vet. Med. 3: 915-747. doi: 10.4061/2011/915747.\u003c/li\u003e\n\u003cli\u003eHobson J, Duffield T, Kelton D, Lissemore K, Hietala S and Leslie K (2002) Neospora caninum serostatus and milk production in Holstein cattle. JAVMA. 221: 1160-1164. https://doi.org/10.2460/javma.2002.221.1160.\u003c/li\u003e\n\u003cli\u003eMoore D, Ode\u0026oacute;n A, Venturini M and Campero C (2005) Neosporosis bovina. General concepts, immunity and perspectives for vaccination. Rev Argent Microbiol. 37: 217-228. http://www.scielo.org.ar/scielo.php?script=sci_arttext\u0026amp;pid=S0325-75412005000400011\u0026amp;lng=es.\u003c/li\u003e\n\u003cli\u003eNekouei O, VanLeeuwen J, Stryhn H, Kelton D and Keefe G (2016). Lifetime effects of infection with bovine leukemia virus on longevity and milk production of dairy cows. Prev Vet Med. 133:1-9. doi: 10.1016/j.prevetmed.2016.09.011. \u003c/li\u003e\n\u003cli\u003eNorby B, Bartlett PC, Byrem TM and Erskine RJ (2016) Effect of infection with bovine leukemia virus on milk production in Michigan dairy cows. J. Dairy Sci. 99: 2043-2052. doi: 10.3168/jds.2015-10089.\u003c/li\u003e\n\u003cli\u003eNorton EC, Dowd BE and Maciejewski ML (2018) Odds Ratios\u0026mdash;Current Best Practice and Use. JAMA. 320: 84\u0026ndash;85. https://doi.org/10.1001/JAMA.2018.6971. \u003c/li\u003e\n\u003cli\u003eOrtega D, S\u0026aacute;nchez A, Tob\u0026oacute;n J, Chaparro Y, Cort\u0026eacute;s S and Guti\u0026eacute;rrez M (2016) Seroprevalence and risk factors associated with bovine leukemia virus in Colombia. J. Vet. Med. Anim. Health. 8:35-43. doi: 10.5897/JVMAH2016.0457.\u003c/li\u003e\n\u003cli\u003eRhodes JK, Pelzer KD and Johnson YJ (2003) Economic implications of bovine leukemia virus infection in mid-Atlantic dairy herds. JAVMA. 3: 34-52. doi:10.2460/javma.2003.223.346.\u003c/li\u003e\n\u003cli\u003eRodriguez S, Gianola D and Shook G (2000) Evaluation of models for somatic cell score lactation patterns in Holsteins. Livest. Prod. Sci. 67: 19\u0026ndash;30. doi: 10.1016/s0301-6226(00)00193-7.\u003c/li\u003e\n\u003cli\u003eRomero JJ, D\u0026aacute;vila G, Beita G and Dolz G (2014) Effect of serological status of the Bovine Leucosis Virus (BLV) on milk production of dairy herds in Costa Rica. Agron. Costarricense. 30: 43-55. https://www.revistas.una.ac.cr/index.php/veterinaria/article/view/6324.\u003c/li\u003e\n\u003cli\u003eTiwari A, Vanleeuwen JA, Dohoo IR, Keefe GP, Haddad JP, Tremblay R, Scott HM and Whiting T (2007) Production effects of pathogens causing bovine leukosis, bovine viral diarrhea, paratuberculosis, and neosporosis. J. Dairy Sci. 90: 659-69. doi: 10.3168/jds.S0022-0302(07)71548-5.\u003c/li\u003e\n\u003cli\u003e\u0026Uacute;suga-Monroy C, Echeverri J and L\u0026oacute;pez A (2018) Presencia de los genotipos 1 y 3 del virus de la leucemia bovina en Antioquia, Colombia. Rev. U.D.C.A Act. y Div. Cient. 21:119-126. https://doi.org/10.31910/rudca.v21.n1.2018.670.\u003c/li\u003e\n\u003cli\u003eWu D, Murakami K, Morooka A, Jin H and Sentsui H (2003) In vivo transcription of bovine leukemia virus and bovine immunodeficiency-like virus. Virus Res.2: 81-87. doi: 10.1016/s0168-1702(03)00222-3.\u003c/li\u003e\n\u003cli\u003eYue X, Steeneveld W, Van der Voort M, Van Schaik G, Vernooij J, Van Duijn L, Veldhuis A and Hogeveen H (2021) The effect of bovine viral diarrhea virus introduction on milk production of Dutch dairy herds. J. Dairy Sci. 104:2074-2086. doi: 10.3168/jds.2020-18866. \u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"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":"Antibodies, Dairy Herds pathogens, Epidemiology, Milk production","lastPublishedDoi":"10.21203/rs.3.rs-8232906/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8232906/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe objective was to compare seropositive and seronegative animals to bovine leukosis virus (BLV), bovine viral diarrhea (BVD) and Neospora canis (Nc) in seven productive characteristics (adjusted milk production (PDNa), percentage of adjusted protein (PPa), kilograms of adjusted protein (KgPROa), percentage of adjusted fat (PFa), kilograms of adjusted fat (KgFa), somatic cell score (SCS), all adjusted to 305 days, and duration of lactation (DurL)), and in six reproductive characteristics (age at first service of heifers (AgeFSh), services per conception in heifers (SCh), services per conception in cows (SC), age at parturition (AgeP), days open (DO) and calving interval (CI)). The presence of BLV resulted in low levels for KgPROa, KgFa, and high CI in infected cows. For AgeP, SCh and SC there was no effect of BLV seropositivity. It was a tendency of BLV to affect negatively AgeFSh, PDNa, DO, and SCS. Nc presence had negative effect on SC. A tendency to present a negative effect by DVB was found for PDNa; a significant effect of the interaction between DVB-Nc pathogens on PFa was found, and a tendency to present a negative effect of the interaction between DVB-Nc on KgFa and between BLV-DVB on CI.\u003c/p\u003e","manuscriptTitle":"Effect of seropositivity to bovine leukosis virus, bovine viral diarrhea and neosporosis on productive and reproductive indices in dairy herds","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-04 08:28:36","doi":"10.21203/rs.3.rs-8232906/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":"9e5a988e-7c9e-457d-b887-4ed596f16476","owner":[],"postedDate":"December 4th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-12-20T12:39:00+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-04 08:28:36","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8232906","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8232906","identity":"rs-8232906","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}