Resumo: A diarréia neonatal em bezerros (DNB) é uma doença infecciosa grave em todo o mundo. No Uruguai, a taxa de mortalidade de bezerros associada a doenças infecciosas é alta. O colostro representa a principal fonte de anticorpos e está correlacionado com bons indicadores de saúde e sobrevivência durante a lactação. A vacinação contra a DNB melhora a composição de imunoglobulinas do colostro em vacas prenhes e o seu correto consumo garante a transmissão de anticorpos ao neonato. As vacinas contra DNB geralmente contêm bacterina ou fímbrias purificadas de E. coli, como a bacterina de E. coli CS31A+, bem como antígenos virais. A prevalência de clpG é uma das mais altas entre os genes de virulência de E. coli em fezes de bezerros no Uruguai. ClpG é a proteína estrutural da adesina CS31A. O objetivo do trabalho foi determinar o nível de anticorpos anti-ClpG no colostro de vacas Holandesas não vacinadas e vacinadas contra DNB no Uruguai. O estado funcional da glândula mamária foi analisado. Não foram encontradas diferenças significativas na composição de proteína ou lactose. As diferenças em termos de gordura foram consideradas dentro da média do colostro. Para as análises de anticorpos, uma proteína ClpG recombinante foi purificada usando um sistema de expressão de E. coli. As análises de ELISA mostraram anticorpos anti-ClpG em ambos os grupos, refletindo a exposição natural das vacas às cepas de E. coli CS31A+. Com o modelo misto utilizado, não foi detectada homogeneidade de variância, mas foram encontradas diferenças significativas nas medianas dos valores de IgG entre vacas vacinadas e não vacinadas. Em vacas vacinadas, foi observada uma tendência de aumento de IgG anti-ClpG no colostro, o que poderia resultar em um melhor resultado para os bezerros se a transferência passiva ocorresse de forma efetiva.

Resumen: La diarrea neonatal de terneros (DNT) es una enfermedad infecciosa grave a nivel mundial. En Uruguay, la tasa de mortalidad de terneros asociada a enfermedades infecciosas es alta. El calostro constituye la principal fuente de anticuerpos y se correlaciona con buenas trazas de salud y supervivencia durante la lactancia. La vacunación contra la DNT mejora la composición de inmunoglobulinas del calostro en vacas preñadas y su correcto consumo asegura la transmisión de anticuerpos al neonato. Las vacunas contra la DNT frecuentemente contienen bacterina o fimbrias purificadas de E. coli, como bacterina de E. coli CS31A+, así como antígenos virales. La prevalencia de clpG es una de las más altas entre los genes de virulencia de E. coli en heces de terneros en Uruguay. ClpG es la proteína estructural de la adhesina CS31A. El objetivo del trabajo fue determinar el nivel de anticuerpos anti-ClpG en calostro de vacas holstein-friesian sin vacunar y vacunadas contra la DNT en Uruguay. Se analizó el estado funcional de la glándula mamaria. No se encontraron diferencias significativas en la composición de proteína o lactosa. Las diferencias en términos de la grasa se asumieron dentro del promedio para el calostro. Para los análisis de anticuerpos se purificó una proteína ClpG recombinante usando un sistema de expresión en E. coli. Los análisis de ELISA mostraron anticuerpos anti-ClpG en ambos grupos, lo que refleja la exposición natural de las vacas a cepas E. coli CS31A+. Con el modelo mixto utilizado no se detectó homogeneidad de varianza, pero sí diferencias significativas en las medianas de los valores de IgG entre vacas vacunadas y no vacunadas. En vacas vacunadas se observó una tendencia de aumento de IgG anti-ClpG en el calostro, lo que podría resultar en un mejor resultado para los terneros si la transferencia pasiva ocurre efectivamente.

Abstract: Neonatal calf diarrhea (NCD) is a severe infectious disease, distributed worldwide. In Uruguay, the calf mortality rate in dairy farms associated with infectious diseases is high. Colostrum intake constitutes the primary source of antibodies of neonates and correlates with good tracers of health and survival during the suckling stage. Vaccination against NCD improves the colostrum’s immunoglobulin composition in pregnant cows. Its correct consumption ensures the transmission of antibodies to the calf and should prevent or reduce the occurrence and outcome of diseases. Several vaccines against NCD are on the market, containing E. coli bacterin, purified E. coli fimbriae together with toxoids, and viral antigens. E. coli CS31A+ bacterin have been included in some vaccines against NCD. The prevalence of clpG is one of the highest among E. coli virulence genes in calves feces in Uruguay. ClpG is the structural protein of CS31A adhesin. This work aimed to determine the level of anti-ClpG antibodies in the colostrum of Holstein-Friesian cows without vaccination and vaccinated against NCD in Uruguay. The colostrum composition was analyzed to determine the functional state of the mammary gland. Non-significant differences were determined in the colostrum-protein or -lactose composition. The differences in terms of fat were assumed on the average for colostrum. A recombinant ClpG protein was purified using a prokaryotic expression system from E. coli. ELISA analyses showed anti-ClpG antibodies in both groups of bovines, reflecting the natural exposure of cows to E. coli CS31A+ strains. Mixed model analysis showed no variance homogeneity between groups but significant differences in medians of the IgG values between groups of cows. A tendency to increase the amount of IgG against ClpG in the colostrum of vaccinated cows was observed, which can result in a better outcome for the calves if the passive transfer of IgG effectively occurs.

RESUMO Este estudo observacional descreve os efeitos de curto e longo prazo de fatores maternos em 226 novilhas Holandesas e suas proles. Foram obtidos dados maternos e informações do registro leiteiro. Novilhas jovens foram avaliadas, na janela de 60 a 105 dias de vida, com o escore de saúde, índice de desempenho e amostras de sangue para medir biomarcadores inflamatórios. Dados prospectivos sobre reprodução foram obtidos dos registros da fazenda. O peso das novilhas eutócicas foi superior ao das novilhas que nasceram de parto distócico. A proteína total plasmática e o peso foram maiores nas proles de vacas multíparas do que nas proles das primíparas. Bezerras que nasceram mais leves e no verão apresentaram menores concentrações de proteína total e índices de desempenho. A pontuação do escore fecal foi maior em bezerras nascidas no verão e nos meses frios para DRB. A prole de vacas multíparas nascidas a termo apresentou maior precocidade em relação à idade à primeira inseminação artificial e ao primeiro parto. Finalmente, a sazonalidade ao nascimento afetou a perda de prenhez e a idade ao primeiro parto. As novilhas nascidas no inverno tiveram menores taxas de perda de gestação do que as nascidas no verão. Além disso, esses animais eram mais precoces do que os nascidos nas estações frias. 22 leiteiro avaliadas 6 10 vida saúde inflamatórios fazenda distócico primíparas DRB Finalmente disso frias 2 1

ABSTRACT This observational study describes the short- and long-term effects of maternal factors in 226 Holstein heifers and their offspring. We obtained maternal data and information from the dairy register. Young heifers were assessed in the window of 60 to 105 days of life to perform the Calf Health Scoring System and performance index, and blood samples to measure inflammatory biomarkers. Prospective data on reproduction were obtained from dairy farm registers. The eutocic weight was higher than the dystocic calving heifers. Plasma total protein and weight were higher in the offspring of multiparous dams than in those of primiparous dams. Calves that were born lighter and in summer had lower concentrations of total protein and performance indices. The punctuation of the fecal score was higher in calves born in summer and cold months for BRD. Offspring from multiparous dams born at term exhibited greater precocity in terms of age at first artificial insemination and first parturition. Finally, seasonality at birth affected pregnancy loss and age at first calving. Heifers born in winter had lower rates of pregnancy loss than those born in summer. In addition, these animals were more precocious than animals born during the cold seasons. short longterm long 22 register 6 10 index biomarkers registers indices BRD parturition Finally addition seasons 2 1

Abstract Embryo transfer is just one of a range of assisted reproductive technologies – often the last one in a sequence of others – that has revolutionised the cattle breeding industry. The number of in vitro-produced embryos transferred annually now surpasses the number derived by traditional superovulation by a factor of four. Although issues with cryotolerance of IVP embryos, embryo loss, and, in some cases, calf birth weight remain to be fully resolved, IVP embryos are likely here to stay as a tool for genetic improvement in dairy herds, offering increased flexibility in sire usage allowing multiple pregnancies from elite dam-bull combinations to be generated and the ability to produce more embryos per unit time than traditional superovulation. What follows is a short personal look back at the last 30 years; if you are looking for deep insights into the underlying biology regulating embryo development, this is not the place to look! Please refer to some of the excellent recent reviews and research papers cited herein. industry vitroproduced vitro produced four loss cases resolved herds dambull dam bull 3 years development herein

ABSTRACT The objective of this study was to assess the effects of high-concentrate diets with and without the inclusion of soybean hull (SH; 0 or 500.8 g/kg) plus corn (whole or ground) on the performance, morphometric traits, and nutritional and metabolic parameters of crossbred dairy calves. We also aimed to assess the costs associated with the experimental diets employed. Thirty-six male calves with an average weight of 89±18.6 kg and age of 3.5 months were allocated to four treatments, with nine replicates of one calf/pen, in a completely randomized experimental design for 198 days. The inclusion of the SH and the physical form of corn did not influence animal performance or morphometric measurements; however, SH inclusion increased the digestibility of neutral detergent fiber and the intakes of dry matter and neutral detergent fiber, but did not affect total digestible nutrient intake. The physical form of corn did not influence nutrient intake or digestibility, which resulted in similar performance across the animals. Blood glucose levels as well as alkaline phosphatase and creatinine remained elevated regardless of the diet. The use of SH reduced the total plasma cholesterol content, and there was an interaction between the physical form of corn and SH inclusion in relation to creatinine levels, which were higher when using diets with whole corn and SH. Although the inclusion of up to 500.8 g/kg of SH in the diet reduces feed efficiency, its use decreases the cost per kilogram of weight gain. Dairy calves can exhibit satisfactory production performance when fed alternative ingredients such as whole corn or SH, which have a lower cost than ground corn, traditionally used in diet formulations. highconcentrate high concentrate (SH 5008 500 8 500. gkg g traits employed Thirtysix Thirty six 89186 89 18 6 89±18. 35 3 5 3. treatments calfpen calf pen calf/pen 19 days measurements however animals content efficiency gain formulations 50 8918 1 89±18 891 89±1 89±

Resumo A criação de bezerras é uma das atividades mais importantes na bovinocultura leiteira, visto que estas serão os animais de reposição do rebanho. Objetivou-se avaliar o efeito da estação de nascimento da bezerra no desenvolvimento na fase de cria e desempenho reprodutivo e produtivo. O experimento foi conduzido na Fazenda Experimental Glória, da Universidade Federal de Uberlândia. Foram avaliadas 74 bezerras nascidas de janeiro/2018 a março/2020, desde o primeiro dia de vida ao final da sua primeira lactação. Os animais foram categorizados de acordo com a estação de nascimento: primavera/verão (outubro a março) e outono/inverno (abril a setembro). Durante o aleitamento foi avaliado o peso dos animais nos dias: 0, 30, 60 após o nascimento e no desaleitamento. A temperatura retal, o escore de fezes, a ingestão de alimento e o comportamento animal foram monitorados diariamente. Na vida adulta foram avaliadas data da cobertura fértil, do parto e monitorada a produção de leite durante a primeira lactação. As variáveis analisadas foram: ganho de peso durante o aleitamento, ocorrência de doenças na fase de aleitamento, porcentagem de novilhas que pariram, idade ao primeiro parto e média de produção de leite da primeira lactação de acordo com a estação de nascimento. As variáveis contínuas foram analisadas por análise de variância e as variáveis binomiais por regressão logística no programa MINITAB. As bezerras nascidas na estação outono/inverno apresentam maior peso aos 30 dias, porém esta diferença foi compensada durante o aleitamento, não interferindo no desempenho reprodutivo e produtivo. leiteira rebanho Objetivouse Objetivou se produtivo Glória Uberlândia 7 janeiro2018 janeiro 2018 janeiro/201 março2020 março 2020 março/2020 primaveraverão primavera verão outubro outonoinverno outono inverno abril setembro. setembro . setembro) dias 0 6 desaleitamento retal fezes diariamente fértil pariram MINITAB 3 janeiro201 201 janeiro/20 março202 202 março/202 janeiro20 20 janeiro/2 março20 março/20 janeiro2 2 janeiro/ março2 março/2 março/

Abstract Raising heifers is one of the most important activities in dairy farming because heifers eventually replace the herd. This study was performed to evaluate how the calf’s birth season affects its early development and its reproductive and productive performance. The experiment was conducted at the Glória Experimental Farm of the Federal University of Uberlândia, Minas Gerais, Brazil. In total, 74 female calves born from January 2018 to March 2020 were evaluated from the first day of life to the end of their first lactation. The animals were classified according to their season of birth: spring/summer (October–March) or fall/winter (April–September). During the initial phase of life, the animals’ weights were assessed on days 0, 30, and 60 after birth and at weaning. The rectal temperature, fecal score, feed intake, and animal behavior were recorded daily. In the mature phase of life, the dates of conception and calving were evaluated, and milk production during the first lactation was monitored. The following variables were analyzed according to season of birth: weight gain and occurrence of diseases during the initial phase, percentage of heifers that calved, age at first calving, and average milk production during the first lactation. Continuous variables were analyzed by analysis of variance, and binomial variables were analyzed by logistic regression using the Minitab software program. Calves born in fall/winter had a higher weight at 30 days; however, this difference was compensated for during the initial phase and did not interfere with reproductive and productive performance. herd calfs calf s performance Uberlândia Gerais Brazil total 7 201 202 springsummer spring summer October–March OctoberMarch October (October–March fallwinter fall winter April–September. AprilSeptember April–September . April September (April–September) 0 6 weaning temperature score intake daily monitored calved variance program 3 however 20 (April–September 2

ABSTRACT The objective of this study was to assess the effects of two levels of soybean hulls (0 and 400.1 g/kg) and whole or ground corn in the diet of newborn crossbred dairy male calves on intake, performance, blood indicators, and feeding cost. Twenty-eight calves with an average weight of 33.0±6.2 kg and four days of age were distributed into four treatment groups in a completely randomized design (n = 7) for 56 days. Weekly samples of feed, diets, and leftovers were collected to determine dry matter and nutrient intakes. To evaluate apparent digestibility, samples were taken using titanium dioxide as a maker. Blood samples were also collected to evaluate blood indicators. The inclusion of soybean hulls resulted in greater neutral detergent fiber intake by the calves, but reduced their non-fibrous carbohydrates intake, which was also reduced by the use of whole corn in the diet. Although the total digestible nutrients content of diets decreased with the use of whole corn and inclusion of soybean hulls, its intake did not vary (0.75 kg/d), regardless of the factors analyzed. The apparent digestibilities of dry matter (0.87 kg/kg) and crude protein (0.89 kg/kg) were similar, resulting in similar performance between the animals, regardless of the factors analyzed. In the quantities evaluated, the use of soybean hulls or whole corn did not affect blood indicators and was insufficient to reduce feed costs; the cost of daily feed was $2.06, while the cost per kilogram of gain was $3.74. The inclusion of up to 400.1 g/kg of soybean hulls or the replacement of ground corn with whole corn does not affect the performance of crossbred dairy calves during the preweaning period, demonstrating that both can be used in animal feed during this phase of production. 0 ( 4001 400 1 400. gkg g Twentyeight Twenty eight 33062 33 6 2 33.0±6. n 7 5 intakes digestibility maker nonfibrous non fibrous 0.75 075 75 (0.7 kg/d, kgd kg/d , d kg/d) analyzed 0.87 087 87 (0.8 kg/kg kgkg 0.89 089 89 animals evaluated costs 206 06 $2.06 374 3 74 $3.74 period production 40 3306 33.0±6 0.7 07 (0. 0.8 08 8 20 $2.0 37 $3.7 4 330 33.0± 0. $2. $3. 33.0 $2 $3 33. $

Abstract This article provides an overview of assisted reproductive technologies (ART) and genome engineering to improve livestock production systems for the contribution of global sustainability. Most ruminant production systems are conducted on grassland conditions, as is the case of South American countries that are leaders in meat and milk production worldwide with a well-established grass-feed livestock. These systems have many strengths from an environmental perspective and consumer preferences but requires certain improvements to enhance resource efficiency. Reproductive performance is one of the main challenges particularly in cow-calf operations that usually are conducted under adverse conditions and thus ART can make a great contribution. Fixed-time artificial insemination is applied in South America in large scale programs as 20 to 30% of cows receive this technology every year in each country, with greater calving rate and significant herd genetic gain occurred in this region. Sexed semen has also been increasingly implemented, enhancing resource efficiency by a) obtaining desired female replacement and improving animal welfare by avoiding newborn male sacrifice in dairy industry, or b) alternatively producing male calves for beef industry. In vitro embryo production has been massively applied, with this region showing the greatest number of embryos produced worldwide leading to significant improvement in herd genetics and productivity. Although the contribution of these technologies is considerable, further improvements will be required for a significant livestock transformation and novel biotechnologies such as genome editing are already available. Through the CRISPR/Cas-based system it is possible to enhance food yield and quality, avoid animal welfare concerns, overcome animal health threats, and control pests and invasive species harming food production. In summary, a significant enhancement in livestock productivity and resource efficiency can be made through reproductive technologies and genome editing, improving at the same time profitability for farmers, and global food security and sustainability. (ART sustainability wellestablished well established grassfeed grass feed cowcalf cow calf Fixedtime Fixed 2 30 country implemented industry b considerable available CRISPR/Casbased CRISPRCasbased CRISPR/Cas based CRISPR Cas quality concerns threats summary farmers 3 Casbased CRISPRCas

Resumo Objetivou-se avaliar em vacas leiteiras mestiças que pariram um bezerro vivo, o efeito do tipo de parto (normal ou assistido) na ocorrência de desordens uterinas puerperais e no número de inseminações artificiais (IA) por concepção e taxa de prenhez 150 dias pós-parto (DPP). As vacas foram monitoradas durante o parto e o tipo de parto foi classificado como normal ou assistido. O parto normal não precisou de interferência humana, enquanto o parto assistido precisou de auxílio para retirada do bezerro por via vaginal. Foram registrados 825 partos, sendo 7 natimortos (0,85%) e 17 gemelares (2,06%). Foram analisados 801 partos simples, dos quais 766 (95,63%) foram normais e 35 (4,36%) foram assistidos. Foram avaliadas a ocorrência de desordens uterinas como a retenção de placenta associada com metrite (RP/ME) e endometrite clínica (EC). A ocorrência das doenças foi de 10,24% (82/801) para RP/ME, 12,86% para EC e 5.12% para RP/ME com CE. A maioria das vacas com parto normal tiveram puerpério saudável (73,89%), enquanto a maioria das vacas com parto assistido apresentaram desordens uterinas (74,29%). O número de IA por concepção foi semelhante nas vacas que tiveram parto normal ou assistido (2,39±0,08 e 3,00±0,43, P = 0,16). Não houve evidência de influência negativa do tipo de parto na taxa de prenhez 150 DPP de vacas leiteiras mestiças em lactação (P = 0,44). Vacas saudáveis apresentaram maior taxa de prenhez 150 DPP do que vacas afetadas por desordens uterinas no puerpério (51,65 vs. 42,92%). Vacas leiteiras mestiças com parto normal tiveram um puerpério saudável, comparadas às que tiveram parto assistido, por sua vez foram mais susceptíveis as desordens uterinas no puerpério. E vacas com puerpério saudável resultaram em maiores taxas de prenhez aos 150 dias pós parto. Objetivouse Objetivou se vivo (IA 15 pósparto DPP. . (DPP) humana vaginal 82 0,85% 085 0 85 (0,85% 1 2,06%. 206 2,06% 2 06 (2,06%) 80 simples 76 95,63% 9563 95 63 (95,63% 3 4,36% 436 4 36 (4,36% assistidos RPME RP ME (RP/ME EC. (EC) 1024 10 24 10,24 82/801 82801 (82/801 1286 12 86 12,86 512 5 5.12 CE 73,89%, 7389 73,89% , 73 89 (73,89%) 74,29%. 7429 74,29% 74 29 (74,29%) 2,39±0,08 239008 39 08 (2,39±0,0 300043 00 43 3,00±0,43 0,16. 016 0,16 16 0,16) 0,44. 044 0,44 44 0,44) 51,65 5165 51 65 (51,6 vs 42,92%. 4292 42,92% 42 92 42,92%) (DPP 8 0,85 (0,85 20 2,06 (2,06% 95,63 956 9 6 (95,63 4,36 (4,36 (EC 102 10,2 82/80 8280 (82/80 128 12,8 5.1 738 73,89 (73,89% 742 74,29 (74,29% 2,39±0,0 23900 (2,39±0, 30004 3,00±0,4 01 0,1 04 0,4 51,6 516 (51, 429 42,92 0,8 (0,8 2,0 (2,06 95,6 (95,6 4,3 (4,3 10, 82/8 828 (82/8 12, 5. 73,8 (73,89 74,2 (74,29 2,39±0, 2390 (2,39±0 3000 3,00±0, 0, 51, (51 42,9 (0, 2, (2,0 95, (95, 4, (4, 82/ (82/ 73, (73,8 74, (74,2 2,39±0 239 (2,39± 300 3,00±0 (5 42, (0 (2, (95 (4 (82 (73, (74, 2,39± 23 (2,39 30 3,00± ( (2 (9 (8 (73 (74 2,39 (2,3 3,00 (7 2,3 3,0 3,

Abstract The aim of this study was to evaluate the effect of the type of calving (normal or assisted) on the occurrence of puerperal uterine disorders and on the number of artificial inseminations (AI) per conception and pregnancy rate at 150 days postpartum (PPD). Cows were observed during parturition and the type of calving was classified as normal or assisted. Normal calving required no human interference, while assisted calving required a calf removal aid via vaginal access. There were 825 births, 7 stillbirths (0.85%) and 17 twins (2.06%). We analyzed 801 single births, from which 766 (95.63%) were normal and 35 (4.36%) assisted. Were evaluated the uterine disorders occurrence such as retained placenta combined with metritis (PR/ME) and clinical endometritis (CE). The overall occurrences were 10.24% (82/801) of RP/ME, 12.86% for CE and 5.12% for RP/ME and CE. Most of normal calving cows had healthy puerperium (73.89%), whereas a majority of assisted calving cows had uterine disorders (74.29%). The number of AI per conception was similar for cows that had either normal or assisted calving (2.39±0.08 and 3.00±0.43, P = 0.16). There was no evidence of negative influence of calving type on the 150 PPD pregnancy rate of lactating crossbreed dairy cows (P = 0.44). Healthy cows had higher 150 PPD pregnancy rate than cows affected by puerperium uterine disorders (51.65 vs. 42.92%). Normal calving crossbred dairy cows had a healthier puerperium, compared to cows with assisted calving which were more susceptible to puerperium uterine disorders. And cows with a health puerperium have a higher pregnancy rate at 150 days postpartum. (AI 15 PPD. . (PPD) interference access 82 births 0.85% 085 0 85 (0.85% 1 2.06%. 206 2.06% 2 06 (2.06%) 80 76 95.63% 9563 95 63 (95.63% 3 4.36% 436 4 36 (4.36% PR/ME PRME PR ME (PR/ME (CE) 1024 10 24 10.24 82/801 82801 (82/801 RPME RP 1286 12 86 12.86 512 5 5.12 73.89%, 7389 73.89% , 73 89 (73.89%) 74.29%. 7429 74.29% 74 29 (74.29%) 2.39±0.08 239008 39 08 (2.39±0.0 300043 00 43 3.00±0.43 0.16. 016 0.16 16 0.16) 0.44. 044 0.44 44 0.44) 51.65 5165 51 65 (51.6 vs 42.92%. 4292 42.92% 42 92 42.92%) (PPD 8 0.85 (0.85 20 2.06 (2.06% 95.63 956 9 6 (95.63 4.36 (4.36 (CE 102 10.2 82/80 8280 (82/80 128 12.8 5.1 738 73.89 (73.89% 742 74.29 (74.29% 2.39±0.0 23900 (2.39±0. 30004 3.00±0.4 01 0.1 04 0.4 51.6 516 (51. 429 42.92 0.8 (0.8 2.0 (2.06 95.6 (95.6 4.3 (4.3 10. 82/8 828 (82/8 12. 5. 73.8 (73.89 74.2 (74.29 2.39±0. 2390 (2.39±0 3000 3.00±0. 0. 51. (51 42.9 (0. 2. (2.0 95. (95. 4. (4. 82/ (82/ 73. (73.8 74. (74.2 2.39±0 239 (2.39± 300 3.00±0 (5 42. (0 (2. (95 (4 (82 (73. (74. 2.39± 23 (2.39 30 3.00± ( (2 (9 (8 (73 (74 2.39 (2.3 3.00 (7 2.3 3.0 3.

ABSTRACT: The objective of this study was to characterise husbandry and technical-productive practices at the calf rearing stage in dairy farms in Los Lagos Region, southern Chile. A face-to-face survey was applied to 22 dairy farms in Los Lagos Region in 2017. All farms performed artificial calf rearing under either of two systems: total barn confinement (48%) or a mixed system that considers the first stage with confinement and the second stage in open-air paddocks (52%). More than half (52%) of the farms supplied fresh colostrum to the calf from its dam and the rest of the farms used bottle or oesophageal tube. Only 30% of the farms evaluated colostrum quality using colostrometer (densimeter) or refractometer. After the colostrum supply, milk replacers, waste milk, or a mixture of both were used for calf feeding. Most of the farms (66.7%) did not have automated milk-feeding systems and used bottles (88.9%) and buckets (11.1%) instead. On average, calves were handled by 1.5 caretakers (SD: 0.63) of which 63.4% (SD: 40.2) were men. The average age for caretakers was 43.9 years (SD: 12.7), with 23.8% being less than 35 years old. Overall, results from this study can be used to identify key managements that could improve calves’ rearing productive traits.

Resumen El objetivo fue determinar el efecto de la edad al primer parto sobre la longevidad, el número de días productivos y la producción de leche durante toda la vida de las vacas Holstein y Pardo Suizo en la sabana tropical de Honduras. La información se recolectó de tres granjas lecheras con vacas Holstein (n= 1,391) y cuatro granjas con vacas Pardo Suizo (n= 480), nacidas entre 1993 y 2013, manejadas bajo sistemas intensivos. El modelo estadístico que describió las variables de interés incluyó el efecto de la granja, el grupo de edad al primer parto, el período de nacimiento, la estación de nacimiento y la interacción granja x período y el error residual. Se encontraron efectos de la granja, período, el grupo de edad al primer parto y la interacción granja x período en las variables de respuesta. Un efecto favorable de las vacas que tuvieron su primer parto a una edad más temprana en el número de días de producción y la producción de leche durante toda la vida, y un aumento en la longevidad, tanto en vacas Holstein como en vacas Pardo Suizo (P<0.05). En conclusión, las vacas que parieron a una edad temprana tuvieron más días productivos en la granja y produjeron más leche durante su vida productiva. Por lo tanto, hacer que las novillas paran a una edad temprana podría ser una estrategia de manejo para aumentar la productividad en la granja. Sin embargo, se debe tener en cuenta el peso al primer parto y los aspectos fisiológicos del animal.

Abstract The aim was to determine the effect of age at first calving on longevity, lifetime number of productive days and lifetime milk yield of Holstein and Brown Swiss cows in the tropical savanna of Honduras. The information was collected from three dairy farms with Holstein (n = 1,391) and four farms with Brown Swiss cows (n = 480), born from 1993 to 2013, managed under intensive systems. The statistical model that described the variables of interest included the effect of farm, group of age at first calving, period of birth, season of birth and the interaction farm x period and the residual error. Effects of farm, period group of age at first calving and interaction of farm x period were found on the response variables. A favorable effect of the cows that had their first calving at an earlier age on lifetime number of days in production and lifetime milk yield, and an increase in longevity, in both Holstein and Brown Swiss cows (P<0.05). In conclusion, cows that calved at an early age had more productive days in the farm and produced more milk during their productive life. Therefore, make the heifers to calf at an early age could be a management strategy to increase productivity in the farm. However, the weight at first calving and physiological aspects of the animal should be taken into consideration.

Resumen El objetivo fue evaluar el impacto de factores asociados al manejo de la madre y la calidad del calostro sobre la crianza de reemplazos bovinos durante la lactancia, en el sistema de producción de leche a pequeña escala. En 13 unidades de producción se obtuvo información del crecimiento corporal, la alimentación con calostro e información asociada a la madre de 220 becerras Holstein. Las variables de interés fueron: morbilidad, concentración de inmunoglobulinas en el calostro (CIC; <110 mg/ml), concentración de proteína sérica (CPS; <6.6 g/dl), ganancia diaria de peso (GDP; <0.650 kg/día) y ganancia diaria de altura (GDA; <0.222 cm/día). Los factores de estudio fueron: peso corporal al nacimiento (PCN; <42 kg), altura al nacimiento (AN; <82 cm), calostro consumido el primer día (CCPD; <4 l), calostro consumido el primer día/kg de PV (CPDPV), condición corporal al parto (CCP; <3), duración del periodo seco (DPS; >68 días), vacas primíparas (VP) y vacas sin dieta de reto (VSDR). Para determinar el impacto de los factores de estudio sobre los eventos de interés, se obtuvo la razón de momios a partir de análisis de regresión logística múltiple. Los factores identificados para morbilidad fueron CCPD y VP (P<0.1). Los factores para CIC fueron la DPS y VSDR (P<0.1), mientras que para la GDP lo fue VSDR (P<0.1). Finalmente, los factores para GDA fueron VSDR, PCN, AN y CPDPV (P<0.1). Estos resultados sugieren que la nutrición de la madre durante la gestación tardía tiene un impacto importante sobre la salud y el desarrollo corporal de las becerras durante la lactancia. Estudios adicionales deberán determinar los efectos a largo plazo.

Abstract The objective was to evaluate the impact of factors associated with the management of the mother and the quality of colostrum on the calf rearing during lactation, in the small-scale milk production system. In 13 dairy farms, information was obtained on body growth, colostrum feeding and information associated with the mother of 220 Holstein calves. The variables of interest were: morbidity, concentration of immunoglobulins in colostrum (CIC; <110 mg/ml), serum protein concentration (SPC; <6.6 g/dL), daily weight gain (DWG; <0.650 kg/d) and daily height gain (DHG; <0.222 cm/d). The study factors were: body weight at birth (BWB; <42 kg), height at birth (HB; <82 cm), colostrum consumed on the first day (CCFD; <4 l), colostrum consumed on the first day/kg of LW (CFDLW), body condition at calving (BCC; <3), length of the dry period (LDP; >68 d), primiparous cows (PC) and cows without a challenge diet (CWCD). To determine the impact of the study factors on the events of interest, the odds ratio was obtained from multiple logistic regression analyses. The factors identified for morbidity were CCFD and PC (P<0.1). The factors for CIC were LDP and CWCD (P<0.1), while for DWG, it was CWCD (P<0.1). Finally, the factors for DHG were CWCD, BWB, HB and CFDLW (P<0.1). These results suggest that the mother’s nutrition during late gestation has an important impact on the health and body development of calves during lactation. Further studies should determine long-term effects.

ABSTRACT The aim of this study was to estimate the prevalence of subclinical mastitis and identify environmental risk factors in dairy cattle from small producers in the high Peruvian mountains. A cross-sectional study was carried out, analyzing milk samples per mammary quarter from 300 Brown Swss cows belonging to 38 producers from the district of Santa Rosa, Melgar, in Puno, Peru. The area is located at an altitude of 3900-4300 m. The California Mastitis Test (CMT) was used for the detection of subclinical mastitis, while the identification of environmental factors was done through surveys and inspections to the sites. The prevalence of subclinical mastitis was 47.0% (141/300) and 21.2% (254/1200) at the level of cows and mammary quarters, respectively, without significant differences between quarters (p>0.05). The 15.75 and 24.25% of the four mammary quarters were positive to the degree of traces and level 1 of the CMT, respectively. Within the environmental factors, the type of milking (p=0.0004), the let-down of the milk by the calf (p=0.0001) and two milkings per day (p=0.001) were determining factors for the presentation of subclinical mastitis, while the pre-milking hygiene of the cow and the hygiene of the milkers did not denote importance.

RESUMEN El objetivo del estudio fue estimar la prevalencia de mastitis subclínica e identificar los factores de riesgo ambientales en vacunos lecheros de pequeños productores en alta montaña peruana. Se realizó un estudio transversal, analizando muestras de leche por cuarto mamario individual de 300 vacas Brown Swiss pertenecientes a 38 productores del distrito de Santa Rosa, Melgar, en Puno, Perú. La zona se encuentra a 3900-4300 m de altitud. Se utilizó la prueba de Mastitis de California (CMT) para la detección de mastitis subclínica, en tanto que la identificación de los factores ambientales se hizo mediante encuestas e inspecciones en las granjas. La prevalencia de mastitis subclínica fue de 47.0% (141/300) y 21.2% (254/1200) a nivel de vacas y cuartos mamarios, respectivamente, sin diferencias significativas entre cuartos mamarios (p>0.05). El 15.75 y 24.25% de los cuartos mamarios fue positivo al grado de trazas y nivel 1 del CMT, respetivamente. Dentro de los factores ambientales; el tipo de ordeño (p=0.0004), la inducción de la bajada de la leche por el ternero (p=0.0001) y dos ordeños al día (p=0.001) fueron determinantes para la presentación de mastitis subclínica, mientras que la higiene previa al ordeño de la vaca y la higiene del ordeñador no denotan importancia.

Resumo Espécies do gênero Eimeria possuem grande importância para os bezerros devido às perdas econômicas. O objetivo deste estudo foi identificar as espécies de Eimeria que acometem bezerros e os fatores de risco associados à infecção. Amostras fecais (387) foram coletadas de animais de fazendas leiteiras do Agreste Meridional de Pernambuco. As fezes foram avaliadas pela técnica de Gordon & Whitlock e realizada cultura em dicromato de potássio 2,5% para esporulação dos oocistos. Odds ratio (OR) foi calculada para avaliar os fatores de risco. Eimeria spp. foram detectadas em 50,65% (196/387) das amostras analisadas. Foram identificadas onze espécies, sendo E. bovis (26,64%; 548/2057), E. zuernii (19,69%; 405/2057) e E. ellipsoidalis (14,49%; 298/2057) as mais frequentes. Pequenos rebanhos (OR = 1,93), bezerros com idade de até seis meses (OR = 2,12), ausência de esterqueira (OR = 7,52), limpeza quinzenal (OR = 4,71), bezerreiros coletivos (OR = 3,26), ordenha manual (OR = 2,16) e ausência de assistência veterinária (OR = 2,28) foram considerados fatores de risco. Os dados revelaram espécies patogênicas em mais de 50% das propriedades. Dessa forma, ressalta-se a importância da adoção de medidas sanitárias, visando à diminuição da propagação desses protozoários nos rebanhos, e perdas econômicas associadas à infecção.

Abstract Eimeria species have importance to calves because of the economic losses. The aim of this study was to identify the species of Eimeria that affect calves and the risk factors associated with its natural infection. Fecal samples (387) were collected from dairy farms in the southern Agreste of Pernambuco. The feces were evaluated using the Gordon & Whitlock technique and were cultured in 2.5% potassium dichromate for sporulation of oocysts. Odds ratio (OR) were calculated to assess risk factors. Eimeria spp. were detected in 50.65% (196/387) of the samples. Eleven species were identified, being Eimeria bovis (26.64%; 548/2057), Eimeria zuernii (19.69%; 405/2057) and Eimeria ellipsoidalis (14.49%; 298/2057) those more frequent. Small herds (OR = 1.93), calves aged up to six months (OR = 2.12), absence of manure pit (OR = 7.52), fortnightly cleaning (OR = 4.71), collective calf pens (OR = 3.26), manual milking (OR = 2.16) and absence of veterinary care (OR = 2.28) were considered to be risk factors. The data revealed pathogenic species in more than 50% of the farms. Thus, the importance of adopting sanitary measures to reduce the spread of these protozoa in herds should be done, because of economic losses associated with its infection.

RESUMO O presente estudo objetivou investigar a morbidade e a mortalidade associadas às doenças mais comuns no período de criação de bezerras da raça Holandesa, em uma fazenda leiteira de alta produção. As bezerras (n = 600) foram alocadas em três grupos de acordo com a idade: G1 (1-7 dias, n = 216); G2 (30-40 dias, n = 188); G3 (69-85 dias, n = 196). Os animais foram avaliados durante 60 dias, em oito momentos diferentes. A morbidade foi de 47,67% (286/600) para diarreia, 73,00% (438/600) para doença respiratória bovina (DRB) e 3,83% (23/600) para inflamação umbilical (IU). A taxa de mortalidade foi de 2,33% (14/600), para o total de animais avaliados. A morbidade foi diferente entre os grupos, com maior frequência de diarreia (78,85%, 166/216) e IU (6,94%, 15/216) no G1, sendo a maior ocorrência de DRB no G3 (79,59%, 156/196). A diarreia foi associada à DRB no G1 e no G2. Mesmo em fazendas com boas práticas de manejo, há alta morbidade por diarreia e DRB, com a taxa de morbidade por diarreia diminuindo e a de DRB aumentando à medida que os animais envelhecem. Além disso, a diarreia é um importante fator de risco para DRB, especialmente em animais mais jovens.

ABSTRACT The present study aimed to investigate the morbidity and mortality associated with the most common diseases during the rearing period of Holstein calves in a high-production dairy farm. The calves (n = 600) were allocated to three groups based on age: G1 (1-7 days, n = 216), G2 (30-40 days, n = 188), and G3 (69-85 days, n = 196). They were evaluated over 60 days at eight different times. The morbidity rates were 47.67% (286/600) for diarrhea, 73.00% (438/600) for bovine respiratory disease (BRD), and 3.83% (23/600) for umbilical inflammation (UI). The mortality rate was 2.33% (14/600) for all the animals studied. The morbidity differed in the groups, with higher rates of diarrhea (78.85%, 166/216) and UI (6.94%, 15/216) in G1, and the highest rate of BRD in G3 (79.59%, 156/196). Diarrhea was associated with the occurrence of BRD in G1 and G2. Even in farms with good management practices, there is high morbidity associated with diarrhea and BRD, with the morbidity rate for diarrhea decreasing and that for BRD increasing as the animals get older. In addition, diarrhea is an important risk factor for BRD, especially in younger animals.

ABSTRACT Bovine leukemia virus (BLV) is a retroviral agent that primarily affects dairy cattle. Colostrum is the main source of immunoglobulins for calves; however, it is also a vehicle for the vertical transmission of BLV. The aim of this work was to determine the presence of BLV in colostrum and its potential to infect newborn calves. Seven mothers and their seven daughter calves were evaluated. Blood, colostrum, and milk samples were taken. An ELISA was performed to detect BLV in blood, colostrum and milk serums. Furthermore, a PCR test (env gene) was used for BLV detection in blood and colostrum. An identity analysis was used (phylogeny) to verify the origin of the sequences obtained from the DNA of mothers, calves, and colostrum. Six of the seven cows were positive for BLV by ELISA, while five of them were positive by PCR. None of the calves was positive by PCR at birth. However, the BLV provirus was found in two calves on day 15 and in one calf on day 30. The identity of the sequences was confirmed as BLV. Colostrum and milk are vehicles for the vertical transmission of BLV, which explains that three of the seven calves evaluated showed BLV infection during the early postpartum period.

RESUMEN El virus de la leucemia bovina (BLV) es un agente retroviral que afecta principalmente al ganado lechero. El calostro es la principal fuente de inmunoglobulinas para terneros. Sin embargo, también es un vehículo para la transmisión vertical del BLV. El objetivo de este trabajo fue determinar la presencia de BLV en muestras de calostro y su potencial para infectar terneros recién nacidos. Se evaluó un grupo de siete madres y sus siete terneras hijas. Se tomaron muestras de sangre, calostro y leche. Se realizó una prueba ELISA para determinar la presencia de anticuerpos anti-BLV en sueros de sangre, calostro y leche. Además, se realizó la técnica de PCR (gen env) en muestras de sangre de las madres y terneras, y en muestras de calostro. Se realizó un análisis de identidad (filogenia) para verificar el origen de las secuencias obtenidas del ADN de las madres, las terneras y el calostro. Seis de las siete vacas fueron positivas para BLV por ELISA, y cinco de ellas fueron positivas por PCR. Ninguno de los terneros fue positivo por PCR al nacer. Sin embargo, se encontró ADN proviral en dos terneras el día 15 y en otra ternera el día 30. Se confirmó que la identidad de todas las secuencias obtenidas era del BLV. El calostro y la leche son vehículos para la transmisión vertical de BLV, lo que explica que tres de las terneras evaluadas mostraron infección por BLV durante el período posparto temprano.