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Objective: To assess the diurnal behavioral response of beef cattle in feedlot in the dry tropics. Materials and Methods: During fall, a prospective observational study was carried out for six weeks long. At 8:00, 12:00 and 16:00 h, behavioral patterns, temperature and relative humidity were recorded, and the temperature and humidity index was calculated. Cattle were housed in pens provided with polypropylene shade and pens without shade. Results: At 8:00 h, the cattle under shade and cattle without access to shade were subjected to environmental conditions of thermal comfort category (p<0.01); but at 12:00 h cattle under shade were in thermal danger and thermal alert at 16:00 h. For cattle without access to shade at 12:00 and 16:00 h, the thermal danger persisted (p<0.01). Feed access was inhibited at 8:00 and 12:00 h and increased at 16:00 h, but rumination decreased at 8:00 and 16:00 h and increased at 12:00 h (p<0.01). Rest indicators were mostly observed in danger and thermal alert (p<0.01). The agonist indicators were inhibited at 8:00 and 12:00 h (p≤0.04). Social behavior was mostly manifest at 4:00 p.m. (p<0.001). Conclusions: The diurnal expression of bovine behavior related to the climatic factor and the provision of shade, can be inhibited in the hours of highest caloric load expressed as the Temperature and Humidity Index. Key words: animal behaviour, animal welfare, warm season, animal housing, thermal stress, Bos indicus (AGROVOC Multilingual Thesaurus), Objetivo: Valorar la respuesta conductual diurna de bovinos productores de carne en finalización intensiva en el trópico seco. Materiales y Métodos: En el otoño se realizó un estudio observacional prospectivo con duración de seis semanas. A las 8:00, 12:00 y 16:00 h se registraron las pautas conductuales, temperatura ambiente y humedad relativa; el índice de temperatura y humedad fue calculado. Los bovinos se alojaron en corrales provistos de sombra de polipropileno y corrales sin sombra. Resultados: A las 8:00 h todos los bovinos estuvieron sujetos a condiciones ambientales de confort térmico (p<0.01); pero a las 12:00 h los bovinos bajo sombra estuvieron en peligro térmico y a las 16:00 h en alerta térmica, y a las 12:00 y 16:00 h en los bovinos sin acceso a sombra persistió el peligro térmico (p<0.01). El acceso al comedero se inhibió a las 8:00 y 12:00 h e incrementó a las 16:00 h, pero la rumia disminuyó a las 8:00 y 16:00 y aumentó a las 12:00 h (p<0.01). Los indicadores de descanso son mayormente observados en peligro y alerta térmica (p<0.01). Los indicadores agonistas se encuentran inhibidos a las 8:00 y 12:00 h (p≤0.04). La conducta social es mayormente manifiesta a las 16:00 h (p<0.001). Conclusiones: La expresión diurna de la conducta bovina relacionada con el factor climático y la provisión de sombra, puede ser inhibida en las horas de más alta influencia calórica expresada en el índice de temperatura y humedad.

Objective: To assess the diurnal behavioral response of beef cattle in feedlot in the dry tropics. Materials and Methods: During fall, a prospective observational study was carried out for six weeks long. At 8:00, 12:00 and 16:00 h, behavioral patterns, temperature and relative humidity were recorded, and the temperature and humidity index was calculated. Cattle were housed in pens provided with polypropylene shade and pens without shade. Results: At 8:00 h, the cattle under shade and cattle without access to shade were subjected to environmental conditions of thermal comfort category (p<0.01); but at 12:00 h cattle under shade were in thermal danger and thermal alert at 16:00 h. For cattle without access to shade at 12:00 and 16:00 h, the thermal danger persisted (p<0.01). Feed access was inhibited at 8:00 and 12:00 h and increased at 16:00 h, but rumination decreased at 8:00 and 16:00 h and increased at 12:00 h (p<0.01). Rest indicators were mostly observed in danger and thermal alert (p<0.01). The agonist indicators were inhibited at 8:00 and 12:00 h (p≤0.04). Social behavior was mostly manifest at 4:00 p.m. (p<0.001). Conclusions: The diurnal expression of bovine behavior related to the climatic factor and the provision of shade, can be inhibited in the hours of highest caloric load expressed as the Temperature and Humidity Index. Key words: animal behaviour, animal welfare, warm season, animal housing, thermal stress, Bos indicus (AGROVOC Multilingual Thesaurus), Objetivo: Valorar la respuesta conductual diurna de bovinos productores de carne en finalización intensiva en el trópico seco. Materiales y Métodos: En el otoño se realizó un estudio observacional prospectivo con duración de seis semanas. A las 8:00, 12:00 y 16:00 h se registraron las pautas conductuales, temperatura ambiente y humedad relativa; el índice de temperatura y humedad fue calculado. Los bovinos se alojaron en corrales provistos de sombra de polipropileno y corrales sin sombra. Resultados: A las 8:00 h todos los bovinos estuvieron sujetos a condiciones ambientales de confort térmico (p<0.01); pero a las 12:00 h los bovinos bajo sombra estuvieron en peligro térmico y a las 16:00 h en alerta térmica, y a las 12:00 y 16:00 h en los bovinos sin acceso a sombra persistió el peligro térmico (p<0.01). El acceso al comedero se inhibió a las 8:00 y 12:00 h e incrementó a las 16:00 h, pero la rumia disminuyó a las 8:00 y 16:00 y aumentó a las 12:00 h (p<0.01). Los indicadores de descanso son mayormente observados en peligro y alerta térmica (p<0.01). Los indicadores agonistas se encuentran inhibidos a las 8:00 y 12:00 h (p≤0.04). La conducta social es mayormente manifiesta a las 16:00 h (p<0.001). Conclusiones: La expresión diurna de la conducta bovina relacionada con el factor climático y la provisión de sombra, puede ser inhibida en las horas de más alta influencia calórica expresada en el índice de temperatura y humedad.

Background: The Gyr breed is widely used in Colombian low tropic dairy production systems. During the last 10 years, the Asociación Colombiana de Criadores de Ganado Cebú† - ASOCEBU, has been leading a dairy milk control program which led to the creation of a dataset that permits to carry out the first analysis of milk yield in Gyr cattle in the country using records from several herds. Objectives: To study milk production dynamics of Gyr cattle in the Colombian low tropic through the estimation of lactation curves and four derived production parameters: total milk yield between 5 and 305 days (TMY305), peak milk yield (PMY), days at peak (DP) and persistency (P). Methods: 13,798 daily milk yield records from 1,510 cows performing in 103 herds were used; the total number of lactations was 2,480. Four models were considered: Wood, Wiltmink, Papajcsik & Bordero, and a second-degree polynomial. Mean square error, mean absolute error, mean square error of prediction, Akaike and Bayesian information criteria were used to select the model better describing each lactation using the majority rule, that is, the model selected by most criteria was the chosen one. The shape of each fitted lactation curve was checked using basic results from calculus which permitted the classification of the estimated curves into two groups: typical and atypical; only typical functions were used to compute the four aforementioned production parameters. Results: The second-order polynomial was the model most frequently selected, while the Papajcsik & Bordero model had the lowest frequency. Average TMY305, PMY, DP and P were 3,489.86 kg, 17.28 kg, 57.17 days, and 0.83, respectively, with coefficients of variation: 0.27, 0.21, 0.41, and 0.16. Conclusions: This study permitted to identify individuals with outstanding phenotypic performance. To the best of our knowledge, this is the first study of this kind involving thousands of lactations from Gyr cows performing in several regions of Colombian lo, Antecedentes: Gir é uma raça Bos indicus amplamente utilizada em sistemas de produção leiteira no trópico baixo Colombiano. A Asociación Colombiana de Criadores de Ganado Cebú- ASOCEBU, lidera um programa de controle de leite nos últimos 10 anos, o que permitiu à coleta de um conjunto de dados para realizar a primeira análise de produção de leite em bovinos Gir no país com informações de vários rebanhos. Objetivo: Estudar a dinâmica da produção de leite por meio da estimativa das curvas de lactação e quatro parâmetros de produção derivados: produção total de leite entre 5 e 305 dias (TMY305), produção de leite no pico de lactação (PMY), dias em produção de leite no pico de lactação (DP) e persistência (P). Métodos: Foram utilizados 13.798 registros de produção diária de leite de 1.510 vacas de 103 fazendas , totalizando 2.480 lactações. Foram considerados quatro modelos: Wood, Wiltmink, Papajcsik & Bordero e um polinômio de segundo grau. Para selecionar o modelo que melhor descreve cada lactação foram utilizados os seguintes critérios: erro quadrado médio, erro absoluto médio, e erro quadrado médio de predição. O modelo selecionado pela maioria dos parâmetros, de acordo com os critérios de informação de Akaike e Bayesiano, foi o escolhido. A forma de cada curva de lactação ajustada foi verificada utilizando os resultados básicos do cálculo, isso permitiu classificar as curvas estimadas em dois grupos: típico e atípico, e apenas funções típicas foram utilizadas para calcular os quatro parâmetros de produção acima mencionados. Resultados: O polinômio de segunda ordem foi o modelo mais frequentemente selecionado, enquanto o modelo Papajcsik & Bordero apresentou a menor frequência. A média de TMY305, PMY, DP e P foram 3.489,86 kg, 17,28 kg, 57,17 de 0,83, respectivamente, com coeficientes de variação de 0,27, 0,21, 0,41 e 0,16. Conclusões: Este estudo permitiu identificar indivíduos com excelente desempenho fenotípico. De acordo com a literatura atual, este é o primeiro, Antecedentes: La raza Gyr es ampliamente utilizada en las lecherías de trópico bajo en Colombia. Durante los últimos 10 años, la Asociación Colombiana de Criadores de Ganado Cebú – ASOCEBU, ha liderado un programa de control lechero que generó una base de datos que permite llevar a cabo el primer análisis de producción de leche de la raza Gyr en el país, considerando individuos de varias fincas. Objetivos: Caracterizar la dinámica de producción de leche de ganado Gyr en el trópico bajo colombiano mediante la estimación de curvas de lactancia y cuatro parámetros de producción derivados: producción total entre 5 y 305 días (TMY305), pico de lactancia (PMY), días al pico (DP) y persistencia (P). Métodos: Se utilizaron 13.798 registros de producción diaria de leche de 1.510 vacas provenientes de 103 fincas, el total de lactancias fue 2.480. Se consideraron cuatro modelos: Wood, Wiltmink, Papajcsik & Bordero, y un polinomio de segundo grado. Los criterios usados para elegir el modelo que mejor describió cada lactancia fueron: error cuadrático medio, error absoluto medio, error cuadrático medio de predicción, criterio de información de Akaike y criterio de información Bayesiano. Se utilizó el criterio de mayoría, esto es, el modelo seleccionado fue aquel elegido por más criterios. La forma de cada una de las curvas de lactancia estimadas fue chequeada utilizando resultados básicos del cálculo, esto permitió clasificar las curvas estimadas en dos grupos: típicas y atípicas; solamente las curvas típicas fueron empleadas para calcular los cuatro parámetros antes mencionados. Resultados: El polinomio de segundo grado fue el modelo que se seleccionó con mayor frecuencia, mientras que el modelo Papajcsik & Bordero tuvo la menor frecuencia. Los promedios para TMY305, PMY, DP y P fueron 3.489,86 kg, 17,28 kg, 57,17 días, y 0,83, respectivamente, con coeficientes de variación 0,27, 0,21, 0,41 y 0,16. Conclusiones: Este estudio permitió identificar individuos con desempeño fenotípi

Background: No dairy breed or crossbreed has superior overall performance in all environments; therefore, it is necessary to determine which crossbreed is the most suitable for the Mexican tropic and what proportion of European breed is optimum for reproduction. Objective: To assess the effect of the proportion of Bos taurus (Bt) genes on reproductive performance of Holstein×Zebu (HZ) and Brown Swiss×Zebu (BZ) cows, and compare reproductive performance of these genotypes in a dual-purpose production system. Methods: Cows were maintained in a rotational grazing system on African star grass (Cynodon plectostachyus) in Veracruz, Mexico. Cows were milked twice daily. Calves were kept tied to the side of their dams while the cows were milked. Results: The percentage of Bt genes did not affect (p>0.05) fertility traits (age at first calving, days to first service after calving, services per conception, conception rate at first service, days open until conception, gestation length, and calving interval) of BZ cows. In contrast, HZ cows with less than 75% Holstein (H) genes were 0.3 years younger (p<0.05) at first calving and had 39.8 fewer days open (p<0.05) than HZ cows with 75% H genes or more. In addition, the calving interval of HZ cows with less than 75% H genes was 44.8 days shorter (p<0.05) than that of HZ cows with 75% H genes or more. The HZ cows had five fewer days pregnant and were 22.8 kg heavier at calving (p<0.05) than BZ cows. Conclusions: The effect of the percentage of Bt genes on cow fertility depends on the dairy breed used. In general, BZ and HZ cows present similar reproductive performance., Antecedentes: Nenhuma raça ou cruza leiteira tem desempenho geral superior em todos os ambientes; portanto, é necessário determinar qual cruza leiteira é mais apropriada no trópico mexicano e qual proporção da raça europeia é ideal para a reprodução das vacas. Objetivo: Avaliar o efeito da proporção de genes Bos taurus (Bt) no desempenho reprodutivo de vacas Holandês×Zebu (HZ) e Pardo Suíço×Zebu (PZ), e comparar o desempenho reprodutivo desses dois genótipos em sistema de produção de dupla aptidão. Métodos: As vacas foram mantidas em sistema de pastoreio rotacional em capim Estrela de África (Cynodon plectostachyus) em Veracruz, México. As vacas foram ordenhadas duas vezes por dia. Os bezerros foram mantidos ao lado de suas mães enquanto eram ordenhadas. Resultados: A porcentagem dos genes Bt não afetou (p>0,05) nenhuma característica de fertilidade (idade ao primeiro parto, número de dias para o primeiro serviço pós-parto, serviços por concepção, taxa de prenhes no primeiro serviço, dias abertos, período de gestação e intervalo entre partos) das vacas PZ. Em contraste, vacas HC com menos de 75% dos genes Holandês (H) eram 0,3 anos mais jovens (p<0,05) no primeiro parto e tiveram 39,8 dias abertos a menos (p<0,05) do que as vacas HZ com 75% ou mais dos genes H. Além disso, o intervalo de parto das vacas HZ com menos de 75% dos genes H foram 44,8 dias mais curtos (p<0,05) do que as vacas HZ com 75% ou mais de genes H. As vacas HZ tiveram cinco dias de gestação a menos e foram 22,8 kg mais pesadas no parto (p<0,05) do que as PZ. Conclusões: O efeito da porcentagem de genes Bt na fertilidade da vaca dependeu da raça leiteira utilizada. Em geral, as vacas PZ e HZ tiveram desempenho reprodutivo semelhante., Antecedentes: Ninguna raza lechera o cruce tiene un desempeño general superior en todos los ambientes; por lo tanto, es necesario determinar cuál cruce lechero es más apropiado en el trópico mexicano y qué proporción de raza europea es óptima para la reproducción. Objetivo: Evaluar el efecto de la proporción de genes Bos taurus (Bt) en el desempeño reproductivo de vacas cruzadas Holstein×Cebú (HC) y Pardo Suizo×Cebú (PC), y comparar el desempeño reproductivo de estos dos genotipos en un sistema de producción doble propósito. Métodos: Las vacas se mantuvieron en un sistema de pastoreo rotacional en zacate Estrella de África (Cynodon plectostachyus) en Veracruz, México. Las vacas se ordeñaron dos veces al día. Los becerros se mantuvieron atados, a un costado de sus madres mientras éstas se ordeñaron. Resultados: El porcentaje de genes Bt no afectó (p>0,05) ninguna característica de fertilidad (edad a primer parto, días a primer servicio después del parto, servicios por concepción, tasa de preñez a primer servicio, días abiertos a la concepción, duración de la gestación, e intervalo entre partos) de las vacas PC. En contraste, las vacas HC con menos de 75% de genes Holstein (H) fueron 0,3 años más jóvenes (p<0,05) al primer parto y tuvieron 39,8 días abiertos menos (p<0,05) que las vacas HC con 75% de genes H o más. Además, el intervalo entre partos de las vacas HC con menos de 75% de genes H fue 44,8 días más corto (p<0,05) que el de las vacas HC con 75% de genes H o más. Las vacas HC tuvieron cinco días de gestación menos y fueron 22,8 kg más pesadas al parto (p<0,05) que las PC. Conclusiones: El efecto del porcentaje de genes Bt sobre la fertilidad de la vaca depende de la raza lechera usada. En general, las vacas PC y HC tienen similar desempeño reproductivo.

The improvement of milk production of indigenous Sudanese cattle such as Bos indicus Butana and its cross with Holstein is a major goal of the Sudanese government to ensure sufficient healthy nutrition in the country. In this study, we investigated the K232A polymorphism of diacylglycerol acyltransferase (DGAT1), a well-known modulator of milk production in other breeds. We determined allele frequencies and the allele effects on milk production. Therefore, 93 purebred Butana and 203 Butana × Holstein crossbred cattle were genotyped using competitive allele-specific PCR assays. Association analysis was performed using a linear mixed model in R. In purebred Butana cattle, the lysine DGAT1 protein variant K232, which is found to be associated with higher fat and protein contents, as well as higher fat yield was highly frequent at 0.929, while its frequency in Butana × Holstein crossbred cattle was 0.394. Significant effects were found on milk yield (P = 7.6 × 10−20), fat yield (P = 2.2 × 10−17), protein yield (P = 2.0 × 10−19) and lactose yield (P = 4.0 × 10−18) in crossbred cattle. As expected, the protein variant K232 was disadvantageous since it was decreasing milk, protein, and lactose yields by 1.741 kg, 0.063 kg and 0.084 kg, respectively. No significant effects were found for milk fat, protein, and lactose contents. The high frequency of the lysine DGAT1 protein variant K232 in Butana cattle could contribute to their high milk fat content in combination with low milk yield. In Butana × Holstein crossbred cattle, the DGAT1 marker can be used for effective selection and thus genetic improvement of milk production., Peer Reviewed

Background: The Gyr breed is widely used in Colombian low tropic dairy production systems. During the last 10 years, the Asociación Colombiana de Criadores de Ganado Cebú† - ASOCEBU, has been leading a dairy milk control program which led to the creation of a dataset that permits to carry out the first analysis of milk yield in Gyr cattle in the country using records from several herds. Objectives: To study milk production dynamics of Gyr cattle in the Colombian low tropic through the estimation of lactation curves and four derived production parameters: total milk yield between 5 and 305 days (TMY305), peak milk yield (PMY), days at peak (DP) and persistency (P). Methods: 13,798 daily milk yield records from 1,510 cows performing in 103 herds were used; the total number of lactations was 2,480. Four models were considered: Wood, Wiltmink, Papajcsik & Bordero, and a second-degree polynomial. Mean square error, mean absolute error, mean square error of prediction, Akaike and Bayesian information criteria were used to select the model better describing each lactation using the majority rule, that is, the model selected by most criteria was the chosen one. The shape of each fitted lactation curve was checked using basic results from calculus which permitted the classification of the estimated curves into two groups: typical and atypical; only typical functions were used to compute the four aforementioned production parameters. Results: The second-order polynomial was the model most frequently selected, while the Papajcsik & Bordero model had the lowest frequency. Average TMY305, PMY, DP and P were 3,489.86 kg, 17.28 kg, 57.17 days, and 0.83, respectively, with coefficients of variation: 0.27, 0.21, 0.41, and 0.16. Conclusions: This study permitted to identify individuals with outstanding phenotypic performance. To the best of our knowledge, this is the first study of this kind involving thousands of lactations from Gyr cows performing in several regions of Colombian lo, Antecedentes: Gir é uma raça Bos indicus amplamente utilizada em sistemas de produção leiteira no trópico baixo Colombiano. A Asociación Colombiana de Criadores de Ganado Cebú- ASOCEBU, lidera um programa de controle de leite nos últimos 10 anos, o que permitiu à coleta de um conjunto de dados para realizar a primeira análise de produção de leite em bovinos Gir no país com informações de vários rebanhos. Objetivo: Estudar a dinâmica da produção de leite por meio da estimativa das curvas de lactação e quatro parâmetros de produção derivados: produção total de leite entre 5 e 305 dias (TMY305), produção de leite no pico de lactação (PMY), dias em produção de leite no pico de lactação (DP) e persistência (P). Métodos: Foram utilizados 13.798 registros de produção diária de leite de 1.510 vacas de 103 fazendas , totalizando 2.480 lactações. Foram considerados quatro modelos: Wood, Wiltmink, Papajcsik & Bordero e um polinômio de segundo grau. Para selecionar o modelo que melhor descreve cada lactação foram utilizados os seguintes critérios: erro quadrado médio, erro absoluto médio, e erro quadrado médio de predição. O modelo selecionado pela maioria dos parâmetros, de acordo com os critérios de informação de Akaike e Bayesiano, foi o escolhido. A forma de cada curva de lactação ajustada foi verificada utilizando os resultados básicos do cálculo, isso permitiu classificar as curvas estimadas em dois grupos: típico e atípico, e apenas funções típicas foram utilizadas para calcular os quatro parâmetros de produção acima mencionados. Resultados: O polinômio de segunda ordem foi o modelo mais frequentemente selecionado, enquanto o modelo Papajcsik & Bordero apresentou a menor frequência. A média de TMY305, PMY, DP e P foram 3.489,86 kg, 17,28 kg, 57,17 de 0,83, respectivamente, com coeficientes de variação de 0,27, 0,21, 0,41 e 0,16. Conclusões: Este estudo permitiu identificar indivíduos com excelente desempenho fenotípico. De acordo com a literatura atual, este é o primeiro, Antecedentes: La raza Gyr es ampliamente utilizada en las lecherías de trópico bajo en Colombia. Durante los últimos 10 años, la Asociación Colombiana de Criadores de Ganado Cebú – ASOCEBU, ha liderado un programa de control lechero que generó una base de datos que permite llevar a cabo el primer análisis de producción de leche de la raza Gyr en el país, considerando individuos de varias fincas. Objetivos: Caracterizar la dinámica de producción de leche de ganado Gyr en el trópico bajo colombiano mediante la estimación de curvas de lactancia y cuatro parámetros de producción derivados: producción total entre 5 y 305 días (TMY305), pico de lactancia (PMY), días al pico (DP) y persistencia (P). Métodos: Se utilizaron 13.798 registros de producción diaria de leche de 1.510 vacas provenientes de 103 fincas, el total de lactancias fue 2.480. Se consideraron cuatro modelos: Wood, Wiltmink, Papajcsik & Bordero, y un polinomio de segundo grado. Los criterios usados para elegir el modelo que mejor describió cada lactancia fueron: error cuadrático medio, error absoluto medio, error cuadrático medio de predicción, criterio de información de Akaike y criterio de información Bayesiano. Se utilizó el criterio de mayoría, esto es, el modelo seleccionado fue aquel elegido por más criterios. La forma de cada una de las curvas de lactancia estimadas fue chequeada utilizando resultados básicos del cálculo, esto permitió clasificar las curvas estimadas en dos grupos: típicas y atípicas; solamente las curvas típicas fueron empleadas para calcular los cuatro parámetros antes mencionados. Resultados: El polinomio de segundo grado fue el modelo que se seleccionó con mayor frecuencia, mientras que el modelo Papajcsik & Bordero tuvo la menor frecuencia. Los promedios para TMY305, PMY, DP y P fueron 3.489,86 kg, 17,28 kg, 57,17 días, y 0,83, respectivamente, con coeficientes de variación 0,27, 0,21, 0,41 y 0,16. Conclusiones: Este estudio permitió identificar individuos con desempeño fenotípi

Background: No dairy breed or crossbreed has superior overall performance in all environments; therefore, it is necessary to determine which crossbreed is the most suitable for the Mexican tropic and what proportion of European breed is optimum for reproduction. Objective: To assess the effect of the proportion of Bos taurus (Bt) genes on reproductive performance of Holstein×Zebu (HZ) and Brown Swiss×Zebu (BZ) cows, and compare reproductive performance of these genotypes in a dual-purpose production system. Methods: Cows were maintained in a rotational grazing system on African star grass (Cynodon plectostachyus) in Veracruz, Mexico. Cows were milked twice daily. Calves were kept tied to the side of their dams while the cows were milked. Results: The percentage of Bt genes did not affect (p>0.05) fertility traits (age at first calving, days to first service after calving, services per conception, conception rate at first service, days open until conception, gestation length, and calving interval) of BZ cows. In contrast, HZ cows with less than 75% Holstein (H) genes were 0.3 years younger (p<0.05) at first calving and had 39.8 fewer days open (p<0.05) than HZ cows with 75% H genes or more. In addition, the calving interval of HZ cows with less than 75% H genes was 44.8 days shorter (p<0.05) than that of HZ cows with 75% H genes or more. The HZ cows had five fewer days pregnant and were 22.8 kg heavier at calving (p<0.05) than BZ cows. Conclusions: The effect of the percentage of Bt genes on cow fertility depends on the dairy breed used. In general, BZ and HZ cows present similar reproductive performance., Antecedentes: Nenhuma raça ou cruza leiteira tem desempenho geral superior em todos os ambientes; portanto, é necessário determinar qual cruza leiteira é mais apropriada no trópico mexicano e qual proporção da raça europeia é ideal para a reprodução das vacas. Objetivo: Avaliar o efeito da proporção de genes Bos taurus (Bt) no desempenho reprodutivo de vacas Holandês×Zebu (HZ) e Pardo Suíço×Zebu (PZ), e comparar o desempenho reprodutivo desses dois genótipos em sistema de produção de dupla aptidão. Métodos: As vacas foram mantidas em sistema de pastoreio rotacional em capim Estrela de África (Cynodon plectostachyus) em Veracruz, México. As vacas foram ordenhadas duas vezes por dia. Os bezerros foram mantidos ao lado de suas mães enquanto eram ordenhadas. Resultados: A porcentagem dos genes Bt não afetou (p>0,05) nenhuma característica de fertilidade (idade ao primeiro parto, número de dias para o primeiro serviço pós-parto, serviços por concepção, taxa de prenhes no primeiro serviço, dias abertos, período de gestação e intervalo entre partos) das vacas PZ. Em contraste, vacas HC com menos de 75% dos genes Holandês (H) eram 0,3 anos mais jovens (p<0,05) no primeiro parto e tiveram 39,8 dias abertos a menos (p<0,05) do que as vacas HZ com 75% ou mais dos genes H. Além disso, o intervalo de parto das vacas HZ com menos de 75% dos genes H foram 44,8 dias mais curtos (p<0,05) do que as vacas HZ com 75% ou mais de genes H. As vacas HZ tiveram cinco dias de gestação a menos e foram 22,8 kg mais pesadas no parto (p<0,05) do que as PZ. Conclusões: O efeito da porcentagem de genes Bt na fertilidade da vaca dependeu da raça leiteira utilizada. Em geral, as vacas PZ e HZ tiveram desempenho reprodutivo semelhante., Antecedentes: Ninguna raza lechera o cruce tiene un desempeño general superior en todos los ambientes; por lo tanto, es necesario determinar cuál cruce lechero es más apropiado en el trópico mexicano y qué proporción de raza europea es óptima para la reproducción. Objetivo: Evaluar el efecto de la proporción de genes Bos taurus (Bt) en el desempeño reproductivo de vacas cruzadas Holstein×Cebú (HC) y Pardo Suizo×Cebú (PC), y comparar el desempeño reproductivo de estos dos genotipos en un sistema de producción doble propósito. Métodos: Las vacas se mantuvieron en un sistema de pastoreo rotacional en zacate Estrella de África (Cynodon plectostachyus) en Veracruz, México. Las vacas se ordeñaron dos veces al día. Los becerros se mantuvieron atados, a un costado de sus madres mientras éstas se ordeñaron. Resultados: El porcentaje de genes Bt no afectó (p>0,05) ninguna característica de fertilidad (edad a primer parto, días a primer servicio después del parto, servicios por concepción, tasa de preñez a primer servicio, días abiertos a la concepción, duración de la gestación, e intervalo entre partos) de las vacas PC. En contraste, las vacas HC con menos de 75% de genes Holstein (H) fueron 0,3 años más jóvenes (p<0,05) al primer parto y tuvieron 39,8 días abiertos menos (p<0,05) que las vacas HC con 75% de genes H o más. Además, el intervalo entre partos de las vacas HC con menos de 75% de genes H fue 44,8 días más corto (p<0,05) que el de las vacas HC con 75% de genes H o más. Las vacas HC tuvieron cinco días de gestación menos y fueron 22,8 kg más pesadas al parto (p<0,05) que las PC. Conclusiones: El efecto del porcentaje de genes Bt sobre la fertilidad de la vaca depende de la raza lechera usada. En general, las vacas PC y HC tienen similar desempeño reproductivo.

The Bos indicus zebu cattle Butana is the most commonly used indigenous dairy cattle breed in Sudan. In the last years, high-yielding Holstein dairy cattle were introgressed into Butana cattle to improve their milk yield and simultaneously keep their good adaption to extreme environmental conditions. With the focus on the improvement of milk production, other problems arose such as an increased susceptibility to mastitis. Thus, genetic selection for mastitis resistance should be considered to maintain healthy and productive cows. In this study, we tested 10 single nucleotide polymorphisms (SNPs) which had been associated with somatic cell score (SCS) in Holstein cattle for association with SCS in 37 purebred Butana and 203 Butana × Holstein crossbred cattle from Sudan. Animals were genotyped by competitive allele-specific PCR assays and association analysis was performed using a linear mixed model. All 10 SNPs were segregating in the crossbred Butana × Holstein populations, but only 8 SNPs in Sudanese purebred Butana cattle. The SNP on chromosome 13 was suggestively associated with SCS in the Butana × Holstein crossbred population (rs109441194, 13:79,365,467, PBF = 0.054) and the SNP on chromosome 19 was significantly associated with SCS in both populations (rs41257403, 19:50,027,458, Butana: PBF = 0.003, Butana × Holstein: PBF = 6.2 × 10−16). The minor allele of both SNPs showed an increase in SCS. Therefore, selection against the disadvantageous minor allele could be used for genetic improvement of mastitis resistance in the studied populations. However, investigations in a bigger population and across the whole genome are needed to identify additional genomic loci., Peer Reviewed

This study was carried out to evaluate the effects of selection criteria for post-weaning daily gain (PWDG) and early sexual heifer precocity (PP14) on the performance, carcass traits and meat quality of Nellore bulls. In year one, 50 animals were selected according to their expected progeny differences (EPDs) for PWDG and grouped as high (HG) or low (LG) groups. In year two, 50 animals were selected according to EPD for PP14 and also grouped as high (HP) or low (LP). After slaughter, samples of the longissimus muscle area (LMA) were used to evaluate meat quality. Most of performance traits were not affected by the selection criteria. However, the HG group had higher dressing percentage (p = 0.028), LMA (p = 0.02) and fat trim in the forequarter (p = 0.04) compared to the LG group. The HP group tended to have greater dry matter intake (p = 0.08), LMA (p = 0.05), rump fat (p = 0.04), heavier striploins (p = 0.07), tenderloins (p = 0.09) and briskets (p = 0.08) compared with LP group. In conclusion, the selection based on divergent groups PWDG or PP14 has a small impact on performance, carcass and meat quality traits.

El presente estudio se lo realizó con la finalidad de identificar a dos tipos de garrapatas, Rhipicephalus microplus y Amblyomma cajennense en vacunos de la parroquia Huambi del cantón Sucúa, ubicada en la provincia de Morona Santiago. Se utilizaron 367 vacunos elegidos al azar, tomando como dato una muestra significativa de la población total de bovinos existentes en la parroquia, en los cuales se tomó información de los niveles de infestación de garrapatas clasificando a los bovinos por la genética y por el sexo. El proceso de recolección de las garrapatas fue de manera manual, donde el tamaño mínimo de los ectoparásitos debía ser mayor a 4mm, estos ectoparásitos obtenidos fueron colocados en alcohol al 70% para su sacrificio, conservación y posterior análisis en frascos debidamente rotulados por animal. En relación a la genética presento mucha más resistencia los Bos Indicus con un 13.6% de animales infestados; los Bos Taurus presentaron el 19,3% de animales y los cruces presentaron una infestación del 32% de animales; todo esto en relación a la especie R. microplus; mientras que para la especie A. cajennense los resultados dieron que para B. indicus un 4% de animales infestados, para B. Taurus un 7% de animales y para los cruces dio un total del 14% de vacunos con infestación ectoparasitaria. En relación al sexo de los bovinos las hembras fueron mucho más susceptibles que los machos teniendo el 22,35% de hembras infestadas y un 18,75% de machos; en relación a la esoecie A. cajennense no hubo diferencias en el grado de infestación entre machos y hembras.

El presente estudio se lo realizó con la finalidad de identificar a dos tipos de garrapatas, Rhipicephalus microplus y Amblyomma cajennense en vacunos de la parroquia Huambi del cantón Sucúa, ubicada en la provincia de Morona Santiago. Se utilizaron 367 vacunos elegidos al azar, tomando como dato una muestra significativa de la población total de bovinos existentes en la parroquia, en los cuales se tomó información de los niveles de infestación de garrapatas clasificando a los bovinos por la genética y por el sexo. El proceso de recolección de las garrapatas fue de manera manual, donde el tamaño mínimo de los ectoparásitos debía ser mayor a 4mm, estos ectoparásitos obtenidos fueron colocados en alcohol al 70% para su sacrificio, conservación y posterior análisis en frascos debidamente rotulados por animal. En relación a la genética presento mucha más resistencia los Bos Indicus con un 13.6% de animales infestados; los Bos Taurus presentaron el 19,3% de animales y los cruces presentaron una infestación del 32% de animales; todo esto en relación a la especie R. microplus; mientras que para la especie A. cajennense los resultados dieron que para B. indicus un 4% de animales infestados, para B. Taurus un 7% de animales y para los cruces dio un total del 14% de vacunos con infestación ectoparasitaria. En relación al sexo de los bovinos las hembras fueron mucho más susceptibles que los machos teniendo el 22,35% de hembras infestadas y un 18,75% de machos; en relación a la esoecie A. cajennense no hubo diferencias en el grado de infestación entre machos y hembras.

El presente estudio se lo realizó con la finalidad de identificar a dos tipos de garrapatas, Rhipicephalus microplus y Amblyomma cajennense en vacunos de la parroquia Huambi del cantón Sucúa, ubicada en la provincia de Morona Santiago. Se utilizaron 367 vacunos elegidos al azar, tomando como dato una muestra significativa de la población total de bovinos existentes en la parroquia, en los cuales se tomó información de los niveles de infestación de garrapatas clasificando a los bovinos por la genética y por el sexo. El proceso de recolección de las garrapatas fue de manera manual, donde el tamaño mínimo de los ectoparásitos debía ser mayor a 4mm, estos ectoparásitos obtenidos fueron colocados en alcohol al 70% para su sacrificio, conservación y posterior análisis en frascos debidamente rotulados por animal. En relación a la genética presento mucha más resistencia los Bos Indicus con un 13.6% de animales infestados; los Bos Taurus presentaron el 19,3% de animales y los cruces presentaron una infestación del 32% de animales; todo esto en relación a la especie R. microplus; mientras que para la especie A. cajennense los resultados dieron que para B. indicus un 4% de animales infestados, para B. Taurus un 7% de animales y para los cruces dio un total del 14% de vacunos con infestación ectoparasitaria. En relación al sexo de los bovinos las hembras fueron mucho más susceptibles que los machos teniendo el 22,35% de hembras infestadas y un 18,75% de machos; en relación a la esoecie A. cajennense no hubo diferencias en el grado de infestación entre machos y hembras.

Objective: The objective of this study was to evaluate the effect of pre-synchronization with progesterone (P4) for 3 and 6 days in Nelore cows in postpartum anestrus period, submitted to a fixed-time artificial insemination program (FTAI). Materials and methods: Seventy-four multiparous Nelore cows with a body condition of 2.5 were used. The cows were submitted to three experimental groups, control group and groups pre-synchronized with P4 for a period of 3 and 6 days. For the determination of postpartum anestrus status, ultrasound scans and blood samples were taken to verify the absence of endogenous P4. Forty-five days after AI, gestation was diagnosed. Data were obtained by descriptive analysis and in the case of presentation of significant differences the Chi-square test was used, considering a frequency of P < 0.05. Results: A higher gestation rate was observed for the group that was pre-synchronized for three days with P4 (40 %), in relation to the groups of six days of pre-synchronization and control (25 % and 32 %, respectively). Conclusion: It is possible to conclude that the pre-synchronization with P4 for three days improved the gestation rate of Nelore cows in the postpartum anestrus period., Resumo Objetivo: O objetivo deste estudo foi avaliar o efeito da pré-sincronização com progesterona (P4) durante 3 e 6 dias em vacas de raça Nelore em período de anestro pós-parto, submetidas a um programa de inseminação artificial em tempo fixo (IATF). Materiais e métodos: Foram utilizadas 74 vacas multíparas da raça Nelore com estado de condição corporal de 2,5. As vacas foram submetidas a três grupos experimentais, grupo controle e grupos pré-sincronizados com P4 por um período de 3 e 6 dias. Para a determinação do estado de anestro pós-parto, foram realizadas ultrassonografias e coleta de amostras de sangue com a finalidade de verificar a ausência de P4 endógena. Quarenta e cinco dias após a IA foi realizado o diagnostico da gestação. Os dados foram obtidos por análise descritiva e no caso de diferenças significativas foi utilizado o teste do Quí-quadrado, considerando-se uma freqüência de P < 0,05. Resultados: Foi observada maior taxa de gestação para o grupo que foi pré-sincronizado por três dias com P4 (40 %), com relação aos grupos de seis dias de pré-sincronização e controle (25 % e 32 %, respetivamente). Conclusão: É possível concluir que a pré-sincronização com P4 por três dias, melhorou a taxa de gestação de vacas Nelore em período de anestro pós-parto., Resumen Objetivo. Este trabajo tuvo como objetivo evaluar el efecto de la pre-sincronización con progesterona (P4) por 3 y 6 días en vacas de raza Nelore en periodo de anestro posparto, sometidas a un programa de inseminación artificial a tiempo fijo (IATF). Materiales y métodos: Fueron utilizadas 74 vacas multíparas de raza Nelore con estado de condición corporal de 2,5. Las vacas fueron sometidas a tres grupos experimentales, grupo control y grupos pre-sincronizados con P4 por un periodo de 3 y 6 días. Para la determinación del estado de anestro posparto, fueron realizadas ecografías y toma de muestras de sangre con la finalidad de verificar la ausencia de P4 endógena. Cuarenta y cinco días después de la IA fue realizado el diagnóstico de la gestación. Los datos fueron obtenidos por análisis descriptivo y en el caso de presentación de diferencias significativas fue utilizado la prueba de Chi-cuadrado, considerándose una frecuencia de P< 0,05. Resultados: Fue observada mayor tasa de gestación para el grupo que fue pre-sincronizado por tres días con P4 (40 %), con relación a los grupos de seis días de pre-sincronización y control (25 % y 32 %, respectivamente). Conclusión: Es posible concluir que la pre-sincronización con P4 por tres días, mejoró la tasa de gestación de vacas de raza Nelore en periodo de anestro posparto.

Several models for predicting dry matter intake (DMI) of replacement dairy heifers have been developed; however, only a few have been evaluated using data from heifers of different breeds raised under tropical conditions. Thus, the objective of this study was to evaluate the DMI equations for dairy heifers managed under tropical conditions. A total of 230 treatment means from 61 studies using dairy heifers (n = 1513 heifers, average body weight = 246 kg) were used. The animals were grouped into two groups based on their genetics: (1) Bos taurus (Holstein, Jersey, Brown Swiss, and Holstein × Jersey) and (2) crossbred (Bos taurus × Bos indicus). Seven previously published DMI equations (HH, HHJ, QUI, STA, 2001 NRC, OFLin, and OFNLin) for heifers were evaluated using mean bias, slope bias, mean squared prediction errors (MSPE) and its decomposition, and other model evaluation statistics. For Bos taurus heifers, our results indicated that OFNLin and HHJ had lower mean bias (0.13 and 0.16 kg/d, respectively) than other models. There was no significant slope or mean bias for HHJ and OFNLin (p > 0.05), indicating agreement between the observed and predicted DMI values. All other models had a significant mean bias (p < 0.05), whereas the QUI model also presented a significant slope bias (p < 0.02). For crossbred heifers, the STA equation was the only one that did not present mean and slope bias significance (p > 0.05). All other DMI models had significant mean bias when evaluated using crossbred data (p < 0.04), and QUI, OFLin, and OFNLin also presented significant slope bias (p < 0.01). Based on our results, predictions from OFNLin and HHJ best represented the observed DMI of Bos taurus heifers (MSPE ≤ 1.25 kg2/d2, mean bias ≤ 0.16 kg/d), whereas STA was the best model for crossbred heifers (MSPE = 1.25 kg2/d2, mean bias = 0.09 k

This study was carried out to evaluate the effects of selection criteria for post-weaning daily gain (PWDG) and early sexual heifer precocity (PP14) on the performance, carcass traits and meat quality of Nellore bulls. In year one, 50 animals were selected according to their expected progeny differences (EPDs) for PWDG and grouped as high (HG) or low (LG) groups. In year two, 50 animals were selected according to EPD for PP14 and also grouped as high (HP) or low (LP). After slaughter, samples of the longissimus muscle area (LMA) were used to evaluate meat quality. Most of performance traits were not affected by the selection criteria. However, the HG group had higher dressing percentage (p = 0.028), LMA (p = 0.02) and fat trim in the forequarter (p = 0.04) compared to the LG group. The HP group tended to have greater dry matter intake (p = 0.08), LMA (p = 0.05), rump fat (p = 0.04), heavier striploins (p = 0.07), tenderloins (p = 0.09) and briskets (p = 0.08) compared with LP group. In conclusion, the selection based on divergent groups PWDG or PP14 has a small impact on performance, carcass and meat quality traits.

Bovine Tuberculosis (bTB) caused by Mycobacterium bovis is a livestock disease of global economic and public health importance. There are currently no effective vaccines available for livestock and so control relies on animal level surveillance and pasteurization of dairy products. A new alternative control approach is to exploit the genetic variability of the host; recent studies have demonstrated that breeding European taurine cattle, such as Holsteins for increased resistance to bTB is feasible. The utility of such an approach is still unknown for African cattle populations. This study aims to assess genetic variation in bTB resistance and the underlying genomic architecture of cattle in Cameroon. We conducted a cross-sectional study of 2,346 slaughter cattle in Cameroon. Retropharyngeal lymph node samples were collected and cultured on Lowenstein Jensen media and the BACTEC MGIT 960 system, and M. bovis was identified using the Hain® Genotype kits. A total of 153 cattle were positive for M. bovis and were archived along with a random selection of negative samples. In this study, we genotyped archived samples from 212 cattle. Their genomic diversity was characterized using PCA, hierarchical clustering and admixture analysis. We assessed genetic variation in bTB resistance using heritability analysis and compared quantitative trait loci. Previous research on this study population have shown that Fulani cattle are more susceptible to bTB than mixed breeds. However, here we show that these apparent phenotypic differences in breeds are not reflected by clear genomic differences. At the genetic level, both the Fulani and mixed cattle show similar patterns of admixture with evidence of both taurine and indicine ancestry. There was little European taurine introgression within the studied population. Hierarchical clustering showed clusters of cattle that differed in their susceptibility to bTB. Our findings allude to bTB resistance being polygenic in nature. This stud

Introduction. There is not much information on pure cattle with a genealogical certificate in Costa Rica. It is necessary to know the status of this population to direct efforts towards the productive improvement of the Zebu cattle breeds. Objective. To update the database of the Costa Rican Cebu Cattle Breeders Association (ASOCEBÚ), characterize this population and analyze the use of males of the gray Brahman breed in the country. Materials and methods. An inventory was done in 121 herds to update the Association’s database to 2018. The information was sorted by breed, sex, age, total animals, breeders, socio-economic region, province, and canton. The frequency of use of gray Brahman breeders was determined. Results. A total of 10 995 pure animals were counted, distributed in six breeds (gray Brahman, red Brahman, Nelore, Gyr, Guzerat, and Indubrasil). The gray Brahman breed predominated with 74.5 % of the population and 76.8 % of the total of breeders. The Chorotega region had the highest registered population (49.5 %) and the highest number of breeders (37.2 %). 55.8 % of the total population came from ten breeders, however, the largest number of herds corresponds to farms with few animals. In the gray Brahman breed, 60.8 % of the population comes from domestic bulls, and 39.2 % from other countries. Conclusion. Registered pure zebu cattle are distributed throughout the whole country. Attention should be put to genetic management to minimize inbreeding. Census and survey managers are encouraged to include the purebred populations in their assessments., Introducción. Existe escasa información sobre ganado puro con certificado genealógico en Costa Rica. Es necesario conocer el estado de esta población para dirigir esfuerzos en la mejora productiva del ganado cebú. Objetivo. Actualizar la base de datos de la Asociación de Criadores de Ganado Cebú de Costa Rica (ASOCEBÚ), caracterizar dicha población y analizar el uso de los machos de la raza Brahman gris en el país. Materiales y métodos. Se realizó un inventario en 121 ganaderías para actualizar la base de datos de la Asociación al año 2018. La información se clasificó por raza, sexo, edad, total de animales, criadores, región socio-económica, provincia y cantón. Se determinó la frecuencia de uso de reproductores Brahman gris. Resultados. Se contabilizaron 10 995 animales puros, distribuidos en seis razas (Brahman gris, Brahman rojo, Nelore, Gyr, Guzerat e Indubrasil). La raza Brahman gris predominó con un 74,5 % de la población y 76,8 % del total de criadores. La región Chorotega presentó la mayor población inscrita (49,5 %) y el mayor número de criadores (37,2 %). El 55,8 % de la población total provino de diez criadores, sin embargo, el mayor número de ganaderías correspondió a fincas con pocos animales. En la raza Brahman gris, el 60,8 % de la población provino de toros nacionales y el 39,2 % del extranjero. Conclusión. Los cebuinos puros registrados se distribuyen en todo el país. Se debe poner atención al manejo genético para minimizar la consanguidad. Se recomienda a los encargados de censos y encuestas, incluir la población de razas puras dentro de las evaluaciones.

Interfaces between protected areas and their peripheries in southern Africa are subject to interactions between wildlife and livestock that vary in frequency and intensity. In these areas, the juxtaposition between production and conservation land uses in a context of increasing anthropisation can create issues associated with human-wildlife coexistence and raises concerns for biodiversity conservation, local development and livelihoods. This literature review aimed at addressing the need to consolidate and gather in one article current knowledge on potential uses of satellite remote sensing (SRS) products by movement ecologists to investigate the sympatry of wildlife/domestic ungulates in savanna interface environments. A keyword querying process of peer reviewed scientific paper, thesis and books has been implemented to identify references that (1) characterize the main environmental drivers impacting buffalo (Syncerus caffer caffer) and cattle (Bos taurus & Bos indicus) movements in southern Africa environments, (2) describe the SRS contribution to discriminate and characterize these drivers. In total, 327 references have been selected and analyzed. Surface water, precipitation, landcover and fire emerged as key drivers impacting the buffalo and cattle movements. These environmental drivers can be efficiently characterized by SRS, mainly through open-access SRS products and standard image processing methods. Applying SRS to better understand buffalo and cattle movements in semi-arid environments provides an operational framework that could be replicated in other type of interface where different wild and domestic species interact. There is, however, a need for animal movement ecologists to reinforce their knowledge of remote sensing and/or to increase pluridisciplinary collaborations.

Introduction. There is not much information on pure cattle with a genealogical certificate in Costa Rica. It is necessary to know the status of this population to direct efforts towards the productive improvement of the Zebu cattle breeds. Objective. To update the database of the Costa Rican Cebu Cattle Breeders Association (ASOCEBÚ), characterize this population and analyze the use of males of the gray Brahman breed in the country. Materials and methods. An inventory was done in 121 herds to update the Association’s database to 2018. The information was sorted by breed, sex, age, total animals, breeders, socio-economic region, province, and canton. The frequency of use of gray Brahman breeders was determined. Results. A total of 10 995 pure animals were counted, distributed in six breeds (gray Brahman, red Brahman, Nelore, Gyr, Guzerat, and Indubrasil). The gray Brahman breed predominated with 74.5 % of the population and 76.8 % of the total of breeders. The Chorotega region had the highest registered population (49.5 %) and the highest number of breeders (37.2 %). 55.8 % of the total population came from ten breeders, however, the largest number of herds corresponds to farms with few animals. In the gray Brahman breed, 60.8 % of the population comes from domestic bulls, and 39.2 % from other countries. Conclusion. Registered pure zebu cattle are distributed throughout the whole country. Attention should be put to genetic management to minimize inbreeding. Census and survey managers are encouraged to include the purebred populations in their assessments., Introducción. Existe escasa información sobre ganado puro con certificado genealógico en Costa Rica. Es necesario conocer el estado de esta población para dirigir esfuerzos en la mejora productiva del ganado cebú. Objetivo. Actualizar la base de datos de la Asociación de Criadores de Ganado Cebú de Costa Rica (ASOCEBÚ), caracterizar dicha población y analizar el uso de los machos de la raza Brahman gris en el país. Materiales y métodos. Se realizó un inventario en 121 ganaderías para actualizar la base de datos de la Asociación al año 2018. La información se clasificó por raza, sexo, edad, total de animales, criadores, región socio-económica, provincia y cantón. Se determinó la frecuencia de uso de reproductores Brahman gris. Resultados. Se contabilizaron 10 995 animales puros, distribuidos en seis razas (Brahman gris, Brahman rojo, Nelore, Gyr, Guzerat e Indubrasil). La raza Brahman gris predominó con un 74,5 % de la población y 76,8 % del total de criadores. La región Chorotega presentó la mayor población inscrita (49,5 %) y el mayor número de criadores (37,2 %). El 55,8 % de la población total provino de diez criadores, sin embargo, el mayor número de ganaderías correspondió a fincas con pocos animales. En la raza Brahman gris, el 60,8 % de la población provino de toros nacionales y el 39,2 % del extranjero. Conclusión. Los cebuinos puros registrados se distribuyen en todo el país. Se debe poner atención al manejo genético para minimizar la consanguidad. Se recomienda a los encargados de censos y encuestas, incluir la población de razas puras dentro de las evaluaciones.

In Brazil, jaguars and pumas both constitute threats to cattle farming due to predation on calves. Since both jaguar and puma populations decline, con-flicts with humans should be avoided in order to prevent poaching, which can lead to the number of wild cats in Brazil decreasing further. The aim of this study was to identify in which environments attacks on cattle mainly occur and whether some groups of cattle are more affected than others. With such knowledge, more effective countermeasures might be deployed in order to prevent attacks, leading to better coexistence. During 2017 and 2018, two farms affected by predation were visited. With the assistance of the ranchers, the sites for attacks were analysed with regard to vegetation types, date, moon phase and traits of the calves. The positions of carcasses were docu-mented with GPS acquired from a mobile phone. Age, breed and sex of the killed animals were also documented. The species of the predator was estab-lished by the ranchers based on the type of damage endured by the carcass, footprints and if it had been covered by foliage. The geographical positions of the attack sites were analysed using ArcGIS. Predated calves were up to one year old, only one calf was older, The age group consisting of calves of 180-270 days was more affected than expected at the farm Sao Bento, as few animals in that age range were present on the farm. Pumas took much younger prey than jaguars. Both pumas and jaguars hunted at one of the farms while the other farm only experienced puma attacks. Overall, more at-tacks occurred in open vegetation than close to or in forests. However, both farms disproportionally consist of open vegetation, and hence forests still seem to be important for jaguars and pumas while hunting. There were a number of attacks recorded within 100 m of houses and roads. Moon phase affected predation; there was a higher risk of killing prey at new moon or close to it. Most of the attacks occurred during the dry se, I Brasilien betraktas jaguarer och pumor som ett hot mot boskapsuppfödningen då de kan döda boskap. Både jaguarer och pumor har minskat i antal. Tjuvjakt kan leda till att antalet vilda kattdjur i Brasilien minskar ännu mera, det är därför viktigt att motverka konflikter mellan människor och vilda katter. Syftet med denna undersökning var att identifiera i vilka miljöer jakt på boskap huvudsakligen uppstår och om vissa grupper av boskap påverkas mer än andra. Med den kunskapen kan effektivare åtgärder kanske vidtas för att förhindra attacker, vilket kan leda till bättre samexistens. Under 2017- 2018 besöktes två gårdar. Med hjälp av boskapsskötare analyserades attacker på boskap med avseende på vegetation, månfas och kalvens egenskaper såsom ålder, ras och kön. Positionerna där boskap hittats dödade bestämdes med GPS i en mobiltelefon. De dödade djurens ålder och kön bestämdes utifrån uppgifter från gårdarna. Med hjälp av boskapsskötare och baserat på skador på kadavret, tassavtryck och om kadavret var täckt med buskage bedömdes det om predatorn var en jaguar eller en puma. Attackernas geografiska positioner har sedan analyserats med ArcGIS. Kalvarnas som dödats var upp till ett år gamla, endast en kalv var äldre. Åldersgruppen 180–270 dagar drabbades mer än förväntat på gården Sao Bento då många boskap i den åldersgruppen sålts och det därför fanns relativt få djur i den åldersgruppen på gården. Pumor tog mycket yngre boskap än jaguarer. Både pumor och jaguarer jagade på en av gårdarna medan den andra gården bara hade pumaattacker. Fler attacker förekom i öppen vegetation än vid skogsområden. Dock bestod bägge gårdarna till största delen av öppen vegetation. I det sammanhanget skedde relativt många attacker ändå vid skogskanter vilket tolkades som att skogsområden ändå verkar vara viktiga för jaguarer och pumpor när de jagar. Det förekom attacker inom 100 m från hus och vägar. Månens faser påverkade antalet attacker; det var högre risk för boskap att dödas vid nymå

In vitro production (IVP) of embryos and associated technologies in cattle have shown significant progress in recent years, in part driven by a better understanding of the full potential of these tools by end users. The combination of IVP with sexed semen (SS) and genomic selection (GS) is being successfully and widely used in North America, South America and Europe. The main advantages offered by these technologies include a higher number of embryos and pregnancies per unit of time, and a wider range of potential female donors from which to retrieve oocytes (including open cyclic females and ones up to 3 months pregnant), including high index genomic calves, a reduced number of sperm required to produce embryos and increased chances of obtaining the desired sex of offspring. However, there are still unresolved aspects of IVP of embryos that limit a wider implementation of the technology, including potentially reduced fertility from the use of SS, reduced oocyte quality after in vitro oocyte maturation and lower embryo cryotolerance, resulting in reduced pregnancy rates compared to in vivo-produced embryos. Nevertheless, promising research results have been reported, and work is in progress to address current deficiencies. The combination of GS, IVP and SS has proven successful in the commercial field in several countries assisting practitioners and cattle producers to improve reproductive performance, efficiency and genetic gain.

In vitro production (IVP) of embryos and associated technologies in cattle have shown significant progress in recent years, in part driven by a better understanding of the full potential of these tools by end users. The combination of IVP with sexed semen (SS) and genomic selection (GS) is being successfully and widely used in North America, South America and Europe. The main advantages offered by these technologies include a higher number of embryos and pregnancies per unit of time, and a wider range of potential female donors from which to retrieve oocytes (including open cyclic females and ones up to 3 months pregnant), including high index genomic calves, a reduced number of sperm required to produce embryos and increased chances of obtaining the desired sex of offspring. However, there are still unresolved aspects of IVP of embryos that limit a wider implementation of the technology, including potentially reduced fertility from the use of SS, reduced oocyte quality after in vitro oocyte maturation and lower embryo cryotolerance, resulting in reduced pregnancy rates compared to in vivo-produced embryos. Nevertheless, promising research results have been reported, and work is in progress to address current deficiencies. The combination of GS, IVP and SS has proven successful in the commercial field in several countries assisting practitioners and cattle producers to improve reproductive performance, efficiency and genetic gain.

Introduction. There is little research about the effect of crossbred between Bos indicus * Bos indicus breeding, however, crossbreeding is an important optimization’s tool used by the livestock producers. Objective. The objective of this study was to determine the behavior of growth characteristics on different proportions of Bos indicus breed crosses. Materials and methods. The analysis was made based on production records of a selected cattle farm with Brahman, Nelore and commercial stock located in the North Pacific region, Costa Rica. The records of 4.294 animals, collected during the 2002-2012 period in the farm, were used; the breed groups included in the study were: Brahman, Nelore, Guzerat, ½ Brahman ½ Nelore, ½ Brahman ½ Guzerat, ¼ Brahman ¾ Nelore, and ¼ Nelore ¾ Brahman. Birth weight, weaning weight, weaning daily weight gain, year old weight, year old daily weight gain, 18 months weight, and 18 months daily weight gain were analyzed according to the breed group of the offspring and the parents. In addition, the non-additive effects (sex, season of birth and year of birth) and their influence on the characteristics were analyzed. Results. It was found that the Brahman, Nelore and ¼ Nelore ¾ Brahman breed groups had the highest weights at all ages, male animals presented higher weights for most of the analyzed characteristics (P <0.05); the animals born in the rainy season presented the highest weights for all the characteristics, in relation to the dry season, while the year of birth did not present trends. The study concluded that the breed group of the mother influenced the early ages of the offspring and the breed group of the father caused differences after one year of age. Likewise, the study concluded that the variables sex and season of birth presented defined behaviors, while the year of birth have fluctuating results. Conclusion. In crossbreds Bos indicus, the breed group of the progenitors have influences in the growth characteristics of progeny, Introducción. Las investigaciones sobre el efecto del cruzamiento entre Bos indicus * Bos indicus son escasos, no obstante, el cruzamiento es una herramienta de optimización importante para el productor pecuario. Objetivo. El objetivo de este trabajo consistió en determinar el comportamiento de las características de crecimiento con base en diferentes proporciones de cruzamientos raciales Bos indicus. Materiales y métodos. El análisis se realizó con base en registros productivos de una ganadería con bovinos seleccionados Brahman y Nelore, y ganado comercial, ubicada en la región Pacífico Norte, Costa Rica. Se utilizaron los registros de 4294 animales, recopilados durante el periodo 2002-2012. Los grupos raciales incluidos en el estudio fueron: Brahman, Nelore, Gucerá, ½ Brahman ½ Nelore, ½ Brahman ½ Gucerá, ¼ Brahman ¾ Nelore y ¼ Nelore ¾ Brahman. Se evaluaron las características de peso al nacimiento, peso al destete, ganancia diaria de peso al destete, peso al año de edad, ganancia diaria de peso al año de edad, peso a los 18 meses, ganancia diaria de peso a los 18 meses, según grupo racial de la cría y de los progenitores. Adicionalmente, se analizaron los efectos no aditivos (sexo, época y año de nacimiento) y su influencia sobre las características. Resultados. Los grupos Brahman, Nelore y ¼ Nelore ¾ Brahman tuvieron los mayores pesos en todas las edades, los animales machos presentaron pesos superiores para la mayor parte de las características analizadas (P<0,05); los animales nacidos en época lluviosa presentaron los mayores pesos para todas las características, respecto a la época seca, mientras que el año de nacimiento no presentó tendencias. La raza de la madre influyó en edades tempranas de la cría y el grupo racial del padre en las diferencias posteriores al año de edad. Además, las variables sexo y época de nacimiento presentaron comportamientos definidos, mientras el año de nacimiento mostró resultados fluctuantes. Conclusión. En cruzamientos raciales

Introduction. There is little research about the effect of crossbred between Bos indicus * Bos indicus breeding, however, crossbreeding is an important optimization’s tool used by the livestock producers. Objective. The objective of this study was to determine the behavior of growth characteristics on different proportions of Bos indicus breed crosses. Materials and methods. The analysis was made based on production records of a selected cattle farm with Brahman, Nelore and commercial stock located in the North Pacific region, Costa Rica. The records of 4.294 animals, collected during the 2002-2012 period in the farm, were used; the breed groups included in the study were: Brahman, Nelore, Guzerat, ½ Brahman ½ Nelore, ½ Brahman ½ Guzerat, ¼ Brahman ¾ Nelore, and ¼ Nelore ¾ Brahman. Birth weight, weaning weight, weaning daily weight gain, year old weight, year old daily weight gain, 18 months weight, and 18 months daily weight gain were analyzed according to the breed group of the offspring and the parents. In addition, the non-additive effects (sex, season of birth and year of birth) and their influence on the characteristics were analyzed. Results. It was found that the Brahman, Nelore and ¼ Nelore ¾ Brahman breed groups had the highest weights at all ages, male animals presented higher weights for most of the analyzed characteristics (P <0.05); the animals born in the rainy season presented the highest weights for all the characteristics, in relation to the dry season, while the year of birth did not present trends. The study concluded that the breed group of the mother influenced the early ages of the offspring and the breed group of the father caused differences after one year of age. Likewise, the study concluded that the variables sex and season of birth presented defined behaviors, while the year of birth have fluctuating results. Conclusion. In crossbreds Bos indicus, the breed group of the progenitors have influences in the growth characteristics of progeny, Introducción. Las investigaciones sobre el efecto del cruzamiento entre Bos indicus * Bos indicus son escasos, no obstante, el cruzamiento es una herramienta de optimización importante para el productor pecuario. Objetivo. El objetivo de este trabajo consistió en determinar el comportamiento de las características de crecimiento con base en diferentes proporciones de cruzamientos raciales Bos indicus. Materiales y métodos. El análisis se realizó con base en registros productivos de una ganadería con bovinos seleccionados Brahman y Nelore, y ganado comercial, ubicada en la región Pacífico Norte, Costa Rica. Se utilizaron los registros de 4294 animales, recopilados durante el periodo 2002-2012. Los grupos raciales incluidos en el estudio fueron: Brahman, Nelore, Gucerá, ½ Brahman ½ Nelore, ½ Brahman ½ Gucerá, ¼ Brahman ¾ Nelore y ¼ Nelore ¾ Brahman. Se evaluaron las características de peso al nacimiento, peso al destete, ganancia diaria de peso al destete, peso al año de edad, ganancia diaria de peso al año de edad, peso a los 18 meses, ganancia diaria de peso a los 18 meses, según grupo racial de la cría y de los progenitores. Adicionalmente, se analizaron los efectos no aditivos (sexo, época y año de nacimiento) y su influencia sobre las características. Resultados. Los grupos Brahman, Nelore y ¼ Nelore ¾ Brahman tuvieron los mayores pesos en todas las edades, los animales machos presentaron pesos superiores para la mayor parte de las características analizadas (P<0,05); los animales nacidos en época lluviosa presentaron los mayores pesos para todas las características, respecto a la época seca, mientras que el año de nacimiento no presentó tendencias. La raza de la madre influyó en edades tempranas de la cría y el grupo racial del padre en las diferencias posteriores al año de edad. Además, las variables sexo y época de nacimiento presentaron comportamientos definidos, mientras el año de nacimiento mostró resultados fluctuantes. Conclusión. En cruzamientos raciales

Syftet med litteraturstudien är att undersöka skillnaderna mellan kons underarter och se vad det finns för åtgärder för att anpassa dem för framtida klimatförändringar. I dagsläget bedöms klimatförändringarna leda till högre temperaturer globalt som kan resultera i värmestressade kor. De höga temperaturerna och den höga luftfuktigheten resulterar i en icke-funktionell värmeavgivningen från kons kropp som därefter orsakar värmestress. Värmestress kan resultera i en minskning av foderintag, tillväxt, fertilitet, och produktionseffektivitet, och det är därför viktigt för kon att hålla sin kroppstemperatur på en jämn nivå. Bos indicus och Bos taurus är underarter till uroxen (Bos primigenius) där Bos indicus anpassat sig till varma klimat medan Bos taurus främst avlats för en hög mjölkavkastning och tillväxt. Studier visar på att Bos indicus höga värmetolerans främst orsakas av dess mindre kroppsyta, effektiva svettkörtlar, ljusa päls, låga metabolism och bra förmåga att avleda värme. För att anpassa Bos taurus till de höga temperaturer finns det lösningar genom skötsel och hantering eller korsningsavel och genomisk selektion där valet av åtgärd beror på gårdens egna resurser. Samtidigt som klimatförändringarna orsakar högre temperaturer globalt ökar också konsumtionen och efterfrågan på kött och mejeriprodukter främst i utvecklingsländer. Från den information som publicerats i denna litteraturstudie dras slutsatsen att Bos taurus behöver bättre värmetolerans för att klara av de framtida klimatförändringarna., The purpose of this study was to examine the differences between cattle subspecies and identify measures to adapt them for future climate changes. At present, climate change is expected to lead to higher temperatures globally, which can result in heat stressed cattle. The high temperature and the high humidity results in a nonfunctional heat release from the body of the cow, which subsequently causes heat stress. Heat stress can result in decrease in food intake, growth, fertility and production efficiency and it is therefore important for the cow to keep the body temperature at an even level. Bos indicus and Bos taurus are subspecies of the aurochs (Bos primigenius) where Bos indicus is adapted to warm climates while Bos taurus is bred for high milk yields and growth. Studies show that the high heat tolerance of Bos indicus is mainly caused by its smaller body surface area, effective sweat glands, light coat, low metabolic rate and the ability to dissipate heat. To adapt the Bos taurus to the high temperatures there are solutions through care and handling or crossbreeding and genomic selection where the choice of measure depends on the farm’s own resources. While climate change causes higher temperatures globally, consumption and demand for meat and dairy products increase in developing countries. From the information published in this literature study, it is concluded that Bos taurus need more heat tolerance to cope with the future climate change.

The liver plays a central role in metabolism and produces important hormones. Hepatic estrogen receptors and the release of insulin-like growth factor 1 (IGF1) are critical links between liver function and the reproductive system. However, the role of liver in pubertal development is not fully understood. To explore this question, we applied transcriptomic analyses to liver samples of pre- and post-pubertal Brahman heifers and identified differentially expressed (DE) genes and genes encoding transcription factors (TFs). Differential expression of genes suggests potential biological mechanisms and pathways linking liver function to puberty. The analyses identified 452 DE genes and 82 TF with significant contribution to differential gene expression by using a regulatory impact factor metric. Brain-derived neurotrophic factor was observed as the most down-regulated gene (P = 0.003) in post-pubertal heifers and we propose this gene influences pubertal development in Brahman heifers. Additionally, co-expression network analysis provided evidence for three TF as key regulators of liver function during pubertal development: the signal transducer and activator of transcription 6, PBX homeobox 2, and polybromo 1. Pathway enrichment analysis identified transforming growth factor-beta and Wnt signaling pathways as significant annotation terms for the list of DE genes and TF in the co-expression network. Molecular information regarding genes and pathways described in this work are important to further our understanding of puberty onset in Brahman heifers.

The liver plays a central role in metabolism and produces important hormones. Hepatic estrogen receptors and the release of insulin-like growth factor 1 (IGF1) are critical links between liver function and the reproductive system. However, the role of liver in pubertal development is not fully understood. To explore this question, we applied transcriptomic analyses to liver samples of pre- and post-pubertal Brahman heifers and identified differentially expressed (DE) genes and genes encoding transcription factors (TFs). Differential expression of genes suggests potential biological mechanisms and pathways linking liver function to puberty. The analyses identified 452 DE genes and 82 TF with significant contribution to differential gene expression by using a regulatory impact factor metric. Brain-derived neurotrophic factor was observed as the most down-regulated gene (P = 0.003) in post-pubertal heifers and we propose this gene influences pubertal development in Brahman heifers. Additionally, co-expression network analysis provided evidence for three TF as key regulators of liver function during pubertal development: the signal transducer and activator of transcription 6, PBX homeobox 2, and polybromo 1. Pathway enrichment analysis identified transforming growth factor-beta and Wnt signaling pathways as significant annotation terms for the list of DE genes and TF in the co-expression network. Molecular information regarding genes and pathways described in this work are important to further our understanding of puberty onset in Brahman heifers.

The objective of this work was to identify 2 genera of tick Rhipicephalus microplus and Amblyomma cajennense in bovines, in the Huambi parish of Canton Sucúa, province of Morona Santiago, for the development of the study 367 bovines were randomly selected, where the level was measured of infestation related to the genetics of bovines, age, sex and grass, ticks were collected manually from bovines and placed in a flask that had 70% alcohol for slaughter and subsequent analysis.In genetics, the Bos Indicus showed greater resistance, with a total of 3 infested bovines of 22, Bos Taurus presented 51 of 264 and the crosses presented 24 of 78 for the genus R. microplus, while for A. cajenennse 1 of 25 Bos Indicus presented infestation, 20 of 263 Bos Taurus and 11 of 78 crosses. For sex, females showed to be more susceptible than males for the genus R. microplus, with 57 of 255 infested females and 21 of 112 males, and for the genus A. cajennense there was no difference between sex. For the age, animals with less than one year showed an average resistance of 7.2% infested bovines and 17.2% of bovines older than one year. In the types of pasture 32% of bovines presented ticks in Brachiarias, 10% in King Grass and 0% in Elefante and Gramalote

The objective of this work was to identify 2 genera of tick Rhipicephalus microplus and Amblyomma cajennense in bovines, in the Huambi parish of Canton Sucúa, province of Morona Santiago, for the development of the study 367 bovines were randomly selected, where the level was measured of infestation related to the genetics of bovines, age, sex and grass, ticks were collected manually from bovines and placed in a flask that had 70% alcohol for slaughter and subsequent analysis.In genetics, the Bos Indicus showed greater resistance, with a total of 3 infested bovines of 22, Bos Taurus presented 51 of 264 and the crosses presented 24 of 78 for the genus R. microplus, while for A. cajenennse 1 of 25 Bos Indicus presented infestation, 20 of 263 Bos Taurus and 11 of 78 crosses. For sex, females showed to be more susceptible than males for the genus R. microplus, with 57 of 255 infested females and 21 of 112 males, and for the genus A. cajennense there was no difference between sex. For the age, animals with less than one year showed an average resistance of 7.2% infested bovines and 17.2% of bovines older than one year. In the types of pasture 32% of bovines presented ticks in Brachiarias, 10% in King Grass and 0% in Elefante and Gramalote

The objective of this work was to identify 2 genera of tick Rhipicephalus microplus and Amblyomma cajennense in bovines, in the Huambi parish of Canton Sucúa, province of Morona Santiago, for the development of the study 367 bovines were randomly selected, where the level was measured of infestation related to the genetics of bovines, age, sex and grass, ticks were collected manually from bovines and placed in a flask that had 70% alcohol for slaughter and subsequent analysis.In genetics, the Bos Indicus showed greater resistance, with a total of 3 infested bovines of 22, Bos Taurus presented 51 of 264 and the crosses presented 24 of 78 for the genus R. microplus, while for A. cajenennse 1 of 25 Bos Indicus presented infestation, 20 of 263 Bos Taurus and 11 of 78 crosses. For sex, females showed to be more susceptible than males for the genus R. microplus, with 57 of 255 infested females and 21 of 112 males, and for the genus A. cajennense there was no difference between sex. For the age, animals with less than one year showed an average resistance of 7.2% infested bovines and 17.2% of bovines older than one year. In the types of pasture 32% of bovines presented ticks in Brachiarias, 10% in King Grass and 0% in Elefante and Gramalote

BACKGROUND: Males of the cattle tick Rhipicephalus microplus produce salivary immunoglobulin-binding proteins and allotypic variations in IgG are associated with tick loads in bovines. These findings indicate that antibody responses may be essential to control tick infestations. Infestation loads with cattle ticks are heritable: some breeds carry high loads of reproductively successful ticks, in others, few ticks feed and they reproduce inefficiently. Different patterns of humoral immunity against tick salivary proteins may explain these phenotypes.METHODS: We describe the profiles of humoral responses against tick salivary proteins elicited during repeated artificial infestations of bovines of a tick-resistant (Nelore) and a tick-susceptible (Holstein) breed. We measured serum levels of total IgG1, IgG2 and IgE immunoglobulins and of IgG1 and IgG2 antibodies specific for tick salivary proteins. With liquid chromatography followed by mass spectrometry we identified tick salivary proteins that were differentially recognized by serum antibodies from tick-resistant and tick-susceptible bovines in immunoblots of tick salivary proteins separated by two-dimensional electrophoresis.RESULTS: Baseline levels of total IgG1 and IgG2 were significantly higher in tick-susceptible Holsteins compared with resistant Nelores. Significant increases in levels of total IgG1, but not of IgG2 accompanied successive infestations in both breeds. Resistant Nelores presented with significantly higher levels of salivary-specific antibodies before and at the first challenge with tick larvae; however, by the third challenge, tick-susceptible Holsteins presented with significantly higher levels of IgG1 and IgG2 tick salivary protein-specific antibodies. Importantly, sera from tick-resistant Nelores reacted with 39 tick salivary proteins in immunoblots of salivary proteins separated in two dimensions by electrophoresis versus only 21 spots reacting with sera from tick-susceptible

Crossbreeding Bos indicus with Bos taurus cattle was explored as a measure to manage ectoparasite infestation specifically comparing tick, mite, fly and lice resistance between Brahman, Sussex and Brahman x Sussex crossbreds. The study area was located in the central Free State on different farms, not more than 15km apart, where cattle breeds were followed and ectoparasites collected on a monthly basis from March 2014 to March 2015. The aim of the study was to determine if Brahman cattle have a natural ectoparasite resistance and if this resistance can be linked to certain breed characteristics when compared to other cattle breeds such as Sussex. A second aim was to establish if the resistance qualities identified are preserved in the cross bred generations. Ectoparasites were collected from both the on-host environment by inspecting 20 cattle from each breed every month as well as the off-host environment through tick drags, fluorescent light traps and sticky fly traps. Ectoparasite abundance regarding both the on-host and off-host environment were also compared to mean monthly temperature and rainfall numbers A total of five Ixodidae species were collected from the animals over the study period including Hyalomma rufipes (3797), R. evertsi evertsi (596), H. truncatum (393), R. decoloratus (29) and R. appendiculatus (30). All of the tick species except for H. truncatum showed a higher affinity for the Sussex breed. The Sussex cattle groups also had the most tick infested individuals over the entire test period. Attachment areas for ticks showed Sussex cattle to have nine areas of tick attachment with Red Brahman two, Grey Brahman three and the crossbred cattle with four attachment areas, corresponding more to the Brahman breeds than the Sussex breed. A greater overview was gained of Diptera diversity and abundance as well as the presence of veterinary important Diptera ectoparasites in the Kroonstad region. Rainfall however, seemed to be a factor influencing host p, Brahman Breeders Association of South Africa

Objective To investigate the mitigating effects of administration of local anaesthetic or systemic meloxicam on the electroencephalographic (EEG) and cardiovascular responses during surgical castration of Bos indicus bull calves. Study design Prospective, randomized, experimental study. Animals Thirty-six 6–8 month-old Bos indicus bull calves, with a mean ± standard deviation weight of 237 ± 19 kg. Methods Animals were allocated randomly to three groups of 12 (group L, 260 mg of 2% lidocaine subcutaneously and intratesticularly 5 minutes prior to castration; group M, 0.5 mg kg−1 of meloxicam subcutaneously 30 minutes prior to castration; group C, no preoperative analgesia administered). Anaesthesia was induced and maintained with halothane (0.9–1.1%) in oxygen. Electroencephalogram, heart rate (HR) and mean blood pressure (MAP) were recorded for 300 seconds prior to (baseline, B) and from the start of surgery (first testicle removal, T1). HR and MAP were compared at 10 second intervals for 90 seconds from the start of T1. Median frequency (F50), spectral edge frequency (F95) and total power of the EEG (Ptot) were analysed using area under the curve comparing T1 to B. Results All EEG variables were significantly different between B and T1 (p ≤ 0.0001). No differences in F50 were found between groups during T1 (p = 0.6491). F95 and Ptot were significantly different between group L and groups C and M during T1 (p = 0.0005 and 0.0163, respectively). There were transient significant changes in HR and MAP in groups L and M compared to group C during the 20–50 second periods. Conclusions The EEG changes indicate nociceptive responses in all three groups during surgical castration, greater in group L compared to groups C and M. Both analgesics attenuated the peracute cardiovascular response. Lidocaine and meloxicam administered prior to castration attenuated these responses in Bos indicus bull c

The objective of the present study was to determine the milk yield of Simmental-Zebu and Brown Swiss-Zebu cows with different proportions of Bos taurus genes. The study was carried out from 1985 to 2007 at the the Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Playa Vicente research station (Veracruz, Mexico). The site presents a humid tropical climate. Milk yield records of Simmental × Zebu and Brown Swiss × Zebu cows with different proportions of Bos taurus genes (50, 62.5 or 75%) were analyzed. The cows were maintained in rotational grazing of the introduced pastures: Star grass (Cynodon plectostachyus) and Guinea (Panicum maximum), and were milked twice a day, after a restricted suckling by their calves. Calves were weaned at 210 days of age. The statistical model included the fixed effects of breed group, year of calving, season of calving, lactation number, and lactation length as a linear covariate; in addition, the model included sire of the cow within breed group as a random effect. The lactation length of Brown Swiss × Zebu cows was greater (P<0.05) than that of Simmental × Zebu cows. Milk yield per lactation, per day and per calving interval of Simmental × Zebu and Brown Swiss × Zebu cows were similar. Third-parity cows yielded more milk (P<0.001) per lactation, per day and per calving interval than first- and second-parity cows. Second-parity cows yielded more milk (P<0.001) per lactation, per day and per calving interval than first-parity cows., El objetivo del presente trabajo fue determinar la producción de leche en vacas Simmental-Cebú y Suizo Pardo-Cebú con diferentes proporciones de genes Bos taurus. El estudio se realizó de 1985 a 2007 en el sitio experimental Playa Vicente (Veracruz, México), del Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias. El sitio presenta un clima tropical húmedo. Se analizaron los registros de producción de leche de vacas Simmental × Cebú y Suizo Pardo × Cebú con diferentes proporciones de genes Bos taurus (50, 62,5 o 75%). Las vacas se mantuvieron en pastoreo rotacional con pastos introducidos: Estrella de África (Cynodon plectostachyus) y Guinea (Panicum maximum), y fueron ordeñadas dos veces al día, después de un amamantamiento restringido del becerro. Estos fueron destetados a los 210 días de edad. El modelo estadístico incluyó los efectos fijos de grupo racial, año y época de parto, número y duración de la lactancia como covariable lineal; además del efecto aleatorio del semental anidado dentro de grupo racial. La duración de la lactancia de las vacas Suizo Pardo × Cebú fue mayor (P<0,05) que en Simmental × Cebú. La producción de leche por lactancia, por día y por día interparto fue similar en las vacas Simmental × Cebú y Suizo Pardo × Cebú. Las vacas de tres lactancias produjeron más leche (P<0,001), por día y por día interparto, que las de una y dos lactancias. Las vacas de dos lactancias produjeron más leche (P<0,001) por lactancia, por día y por día interparto, que las de una lactancia.

El objetivo de esta investigación fue analizar la información de los registros productivos de crías nacidas durante los años 2001 – 2007 de una finca ganadera ubicada en Cañas, Guanacaste. Ahí se evaluaron 3 razas (Brahman. Santa Gertrudis y Simbrah) y sus cruces, los registros fueron recopilados y ordenados en hojas electrónicas, donde se identificaron los animales y se incluyeron otras mediciones calculadas con los datos existentes. Las variables evaluadas fueron peso al nacimiento (PN), peso al destete (PD), Peso al destete a 205 días (Días al destete (DD) -205) y ganancia de peso diaria (GPD). Los terneros de raza pura Brahman tendieron a presentar mayores PN, sin embargo cuando las madres son Brahman puro las crías provenientes de machos no cebuínos tienden a nacer con menor peso, por un efecto propio de las hembras Bos indicus. Los animales Brahman puro presentaron menores PD y menor GPD con respecto a los terneros nacidos de cruces genéticos con Santa Gertrudis y Simmental, debido a un efecto de heterosis materna que estimula una mayor producción de leche, lo que permite una mayor GPD, destetando terneros más pesados. Los terneros nacidos de padres cruzados Bos indicus – Bos taurus, presentan mayores PD y GDP por un efecto de heterosis que beneficia a las crías, permitiendo una mayor adaptación a las condiciones climáticas sin sacrificar la productividad. Los machos en promedio fueron más pesados que las hembras, 1,25 kg al nacimiento y 16,26 kg al destete a 205 días.

El objetivo de esta investigación fue analizar la información de los registros productivos de crías nacidas durante los años 2001 – 2007 de una finca ganadera ubicada en Cañas, Guanacaste. Ahí se evaluaron 3 razas (Brahman. Santa Gertrudis y Simbrah) y sus cruces, los registros fueron recopilados y ordenados en hojas electrónicas, donde se identificaron los animales y se incluyeron otras mediciones calculadas con los datos existentes. Las variables evaluadas fueron peso al nacimiento (PN), peso al destete (PD), Peso al destete a 205 días (Días al destete (DD) -205) y ganancia de peso diaria (GPD). Los terneros de raza pura Brahman tendieron a presentar mayores PN, sin embargo cuando las madres son Brahman puro las crías provenientes de machos no cebuínos tienden a nacer con menor peso, por un efecto propio de las hembras Bos indicus. Los animales Brahman puro presentaron menores PD y menor GPD con respecto a los terneros nacidos de cruces genéticos con Santa Gertrudis y Simmental, debido a un efecto de heterosis materna que estimula una mayor producción de leche, lo que permite una mayor GPD, destetando terneros más pesados. Los terneros nacidos de padres cruzados Bos indicus – Bos taurus, presentan mayores PD y GDP por un efecto de heterosis que beneficia a las crías, permitiendo una mayor adaptación a las condiciones climáticas sin sacrificar la productividad. Los machos en promedio fueron más pesados que las hembras, 1,25 kg al nacimiento y 16,26 kg al destete a 205 días.

The objective of the present study was to determine the milk yield of Simmental-Zebu and Brown Swiss-Zebu cows with different proportions of Bos taurus genes. The study was carried out from 1985 to 2007 at the the Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Playa Vicente research station (Veracruz, Mexico). The site presents a humid tropical climate. Milk yield records of Simmental × Zebu and Brown Swiss × Zebu cows with different proportions of Bos taurus genes (50, 62.5 or 75%) were analyzed. The cows were maintained in rotational grazing of the introduced pastures: Star grass (Cynodon plectostachyus) and Guinea (Panicum maximum), and were milked twice a day, after a restricted suckling by their calves. Calves were weaned at 210 days of age. The statistical model included the fixed effects of breed group, year of calving, season of calving, lactation number, and lactation length as a linear covariate; in addition, the model included sire of the cow within breed group as a random effect. The lactation length of Brown Swiss × Zebu cows was greater (P<0.05) than that of Simmental × Zebu cows. Milk yield per lactation, per day and per calving interval of Simmental × Zebu and Brown Swiss × Zebu cows were similar. Third-parity cows yielded more milk (P<0.001) per lactation, per day and per calving interval than first- and second-parity cows. Second-parity cows yielded more milk (P<0.001) per lactation, per day and per calving interval than first-parity cows., El objetivo del presente trabajo fue determinar la producción de leche en vacas Simmental-Cebú y Suizo Pardo-Cebú con diferentes proporciones de genes Bos taurus. El estudio se realizó de 1985 a 2007 en el sitio experimental Playa Vicente (Veracruz, México), del Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias. El sitio presenta un clima tropical húmedo. Se analizaron los registros de producción de leche de vacas Simmental × Cebú y Suizo Pardo × Cebú con diferentes proporciones de genes Bos taurus (50, 62,5 o 75%). Las vacas se mantuvieron en pastoreo rotacional con pastos introducidos: Estrella de África (Cynodon plectostachyus) y Guinea (Panicum maximum), y fueron ordeñadas dos veces al día, después de un amamantamiento restringido del becerro. Estos fueron destetados a los 210 días de edad. El modelo estadístico incluyó los efectos fijos de grupo racial, año y época de parto, número y duración de la lactancia como covariable lineal; además del efecto aleatorio del semental anidado dentro de grupo racial. La duración de la lactancia de las vacas Suizo Pardo × Cebú fue mayor (P<0,05) que en Simmental × Cebú. La producción de leche por lactancia, por día y por día interparto fue similar en las vacas Simmental × Cebú y Suizo Pardo × Cebú. Las vacas de tres lactancias produjeron más leche (P<0,001), por día y por día interparto, que las de una y dos lactancias. Las vacas de dos lactancias produjeron más leche (P<0,001) por lactancia, por día y por día interparto, que las de una lactancia.

The typical processes of beef carcass fabrication in Venezuela are anatomically described and the equivalence in cut nomenclature with that of México and United States is provided. Additionally, 910 carcasses were fabricated to assess yield (kg and percentages of carcass weight) in products (subprimals), subprimal groups of distinct commercial value (High, Medium, Low) and by-products (bone, fat trimmings) using mean values ± standard deviation (DE), coefficient of variation (CV) and range of values. Once the carcass is ribbed at the 5th intercostal space, subprimals are obtained by deboning and dissecting the muscle masses (saw cutting is seldom used). In terms of yield, the top three (out of 18) individual subprimals were: Solomo Abierto (boneless Chuck Roll, 39.1± 10.88kg; 14.3± 2.84%), Costilla (bone-in Plate, 22kg± 4.15; 8.12± 0.88%) and Solomo de Cuerito (boneless Rib and Loin, 21.6± 3.10kg; 8.0± 0.59%). Cutability values for High-Valued and Medium-Valued subprimal groups were 81.5± 10.3kg (30.2± 1.43%) and 67.3± 14.57kg (24.8± 3.22%), respectively; the latter showing the highest CV (13.0%). Fat trimmings were the most variable by-product (10.1± 2.84%, CV = 28.0%). This report serves as a reference for future studies and could facilitate the commercial language for trading beef cuts between the countries involved., Se describen anatómicamente los procesos de despiece de canales bovinas en Venezuela y las equivalencias en nomenclatura de cortes con México y Estados Unidos. Además, se despostaron 910 canales para evaluar el rendimiento en Kg y porcentaje del peso de canal para productos (cortes sub-primarios) individuales y agrupados por valor comercial (Alto, Mediano y Bajo) y los sub-productos (hueso, grasa recortada), utilizando medias ± desviación estándar, coeficientes de variación (CV) y rangos de valores. Después de cuartear la canal en el 5to espacio intercostal, se obtienen los cortes sub-primarios por deshuese y disección (corte a sierra esporádico). Los tres primeros cortes individuales subprimarios en rendimiento (de 18) fueron: Solomo Abierto (sin hueso, 39.1± 10.88 kg; 14.3± 2.84%), Costilla (22kg± 4.15; 8.12± 0.88%) y Solomo de Cuerito (sin hueso, 21.6± 3.10 kg; 8.0± 0.59%). Valores de rendimiento para grupos de alto y medio valor fueron 81.5± 10.3 kg (30.2± 1.43%) y 67.3± 14.57 kg (24.8± 3.22%), respectivamente; el último mostrando el CV más alto (13.0%). El subproducto más variable (10.1± 2.84%, CV = 28.0%) fue la grasa recortada. Este informe sirve como referencia para futuros estudios y podría facilitar el lenguaje comercial de cortes vacunos entre los países involucrados.

The typical processes of beef carcass fabrication in Venezuela are anatomically described and the equivalence in cut nomenclature with that of México and United States is provided. Additionally, 910 carcasses were fabricated to assess yield (kg and percentages of carcass weight) in products (subprimals), subprimal groups of distinct commercial value (High, Medium, Low) and by-products (bone, fat trimmings) using mean values ± standard deviation (DE), coefficient of variation (CV) and range of values. Once the carcass is ribbed at the 5th intercostal space, subprimals are obtained by deboning and dissecting the muscle masses (saw cutting is seldom used). In terms of yield, the top three (out of 18) individual subprimals were: Solomo Abierto (boneless Chuck Roll, 39.1± 10.88kg; 14.3± 2.84%), Costilla (bone-in Plate, 22kg± 4.15; 8.12± 0.88%) and Solomo de Cuerito (boneless Rib and Loin, 21.6± 3.10kg; 8.0± 0.59%). Cutability values for High-Valued and Medium-Valued subprimal groups were 81.5± 10.3kg (30.2± 1.43%) and 67.3± 14.57kg (24.8± 3.22%), respectively; the latter showing the highest CV (13.0%). Fat trimmings were the most variable by-product (10.1± 2.84%, CV = 28.0%). This report serves as a reference for future studies and could facilitate the commercial language for trading beef cuts between the countries involved., Se describen anatómicamente los procesos de despiece de canales bovinas en Venezuela y las equivalencias en nomenclatura de cortes con México y Estados Unidos. Además, se despostaron 910 canales para evaluar el rendimiento en Kg y porcentaje del peso de canal para productos (cortes sub-primarios) individuales y agrupados por valor comercial (Alto, Mediano y Bajo) y los sub-productos (hueso, grasa recortada), utilizando medias ± desviación estándar, coeficientes de variación (CV) y rangos de valores. Después de cuartear la canal en el 5to espacio intercostal, se obtienen los cortes sub-primarios por deshuese y disección (corte a sierra esporádico). Los tres primeros cortes individuales subprimarios en rendimiento (de 18) fueron: Solomo Abierto (sin hueso, 39.1± 10.88 kg; 14.3± 2.84%), Costilla (22kg± 4.15; 8.12± 0.88%) y Solomo de Cuerito (sin hueso, 21.6± 3.10 kg; 8.0± 0.59%). Valores de rendimiento para grupos de alto y medio valor fueron 81.5± 10.3 kg (30.2± 1.43%) y 67.3± 14.57 kg (24.8± 3.22%), respectivamente; el último mostrando el CV más alto (13.0%). El subproducto más variable (10.1± 2.84%, CV = 28.0%) fue la grasa recortada. Este informe sirve como referencia para futuros estudios y podría facilitar el lenguaje comercial de cortes vacunos entre los países involucrados.

Objective: To investigate the association between scrotal circumference size and sperm characteristics in 194 males of Guzerat breed. Methods: The bulls were divided by age groups from 12 to 36 months of age. The length and width of the testicle and scrotal circumference were measured. Semen was collected from the animals that showed a circumference ≥ 19 cm through transrectal electrostimulation in order to induce ejaculation. The characteristics assessed in the semen were motility, speed, sperm concentration and presence of rounded cells. Results: the correlation between the scrotal circumference with the sperm motility by group of age was positive (r = 0.94; p < 0.005). The present study showed that the presence of proximal cytoplasmic droplet, the rounded cells in the semen and the defects on the head of the spermatozoids are objective evaluation features, which can be used for early selection of sperm production in Guzerat males. Conclusions: The production of sperm with normal rates in the Guzerat breed is achieved when males reach the age of 28 months and a scrotal circumference close to 30 cm., Objetivo: Investigar a associação entre o tamanho da circunferência escrotal e as características espermáticas em 194 machos da raça Guzerá. Métodos: os toros se dividiram por grupos de idades desde os 12 até os 36 meses de idade. Realizaram-se medições do comprimento e da largura do testículo e da circunferência escrotal. Aos animais que apresentaram uma circunferência ≥ 19 cm foi-lhes coletado sêmen mediante eletroestimulação transretal para induzir a ejaculação. As características avaliadas no sêmen foram motilidade, vigor, concentração espermática e presença de células redondeadas. Resultados: a correlação entre a circunferência escrotal com a motilidade espermática por grupo de idade foi positiva (r = 0,94; p < 0,005). O presente estudo demostrou que a presença de gota citoplasmática proximal, as células redondeadas no sêmen ejaculado e os defeitos na cabeça dos espermatozoides são características de avaliação objetiva, as quais podem ser utilizadas para selecionar precocemente a produção de espermatozoides nestes machos Guzerá. Conclusões: a produção de espermatozoides com parâmetros normais na raça Guzerá se conseguem quando os machos chegam à idade de 28 meses e uma circunferência escrotal próxima aos 30 cm., Objetivo: investigar la asociación entre el tamaño de la circunferencia escrotal y las características espermáticas en 194 machos de la raza Guzerat. Métodos: los toros se dividieron por grupos de edades desde los 12 hasta los 36 meses de edad. Se realizaron mediciones del largo y ancho del testículo y de la circunferencia escrotal. A los animales que presentaron una circunferencia ≥ 19 cm se les colectó semen mediante electroestimulación transrectal para inducir la eyaculación. Las características evaluadas en el semen fueron motilidad, vigor, concentración espermática y presencia de células redondeadas. Resultados: la correlación entre la circunferencia escrotal con la motilidad espermática por grupo de edad fue positiva (r = 0,94; p < 0,005). El presente estudio demostró que la presencia de gota citoplasmática proximal, las células redondeadas en el eyaculado y los defectos en la cabeza de los espermatozoides son características de evaluación objetiva, las cuales pueden ser utilizadas para seleccionar precozmente la producción de espermatozoides en estos machos Guzerat. Conclusiones: la producción de espermatozoides con parámetros normales en la raza Guzerat se logran cuando los machos llegan a la edad de 28 meses y una circunferencia escrotal cercana a los 30 cm.

Harsh tropical environments impose serious challenges on poorly adapted species. In beef cattle, tropical adaptation in the form of temperature and disease resistance, coupled with acclimatization to seasonal and limited forage, comes at a cost to production efficiency. Prominent among these costs is delayed onset of puberty, a challenging phenotype to manipulate through traditional breeding mechanisms. Recently, system biology approaches, including gene networks, have been applied to the genetic dissection of complex phenotypes. We aimed at developing and studying gene networks underlying cattle puberty. Our starting material comprises the association results of ~50,000 SNP on 22 traits, including age at puberty, and 2 cattle breed populations: Brahman (n = 843) and Tropical Composite (n = 866). We defined age at puberty as the age at first corpus luteum (AGECL). By capturing the genes harboring mutations minimally associated (P < 0.05) to AGECL or to a set of traits related with AGECL, we derived a gene network for each breed separately and a third network for the combined data set. At the intersection of the 3 networks, we identified candidate genes and pathways that were common to both breeds. Resulting from these analyses, we identified an enrichment of genes involved in axon guidance, cell adhesion, ErbB signaling, and glutamate activity, pathways that are known to affect pulsatile release of GnRH, which is necessary for the onset of puberty. Furthermore, we employed network connectivity and centrality parameters along with a regulatory impact factor metric to identify the key transcription factors (TF) responsible for the molecular regulation of puberty. As a novel finding, we report 5 TF (HIVEP3, TOX, EYA1, NCOA2, and ZFHX4) located in the network intersecting both breeds and interacting with other TF, forming a regulatory network that harmonizes with the recent literature of puberty. Finally, we support our network predictions with evidence derived f

The effect of adding live yeast culture (Saccharomyces cerevisiae, strain 1026), monensin or the combination of both additives to high grain diets on feedlot performance and digestibility of steers, was studied. Nellore steers (n= 72, 339 kg BW, 20 months-old) were fed for 84 days a basal ration (2.58 Mcal EM/kg DM, 14% CP) without additives (control), or with yeast culture (0.6 g Beef Sacc®/ kg DM), monensin (0.3 g Rumensin®/ kg DM) or the combination of both additives to evaluate feedlot performance through individual measurements of dry matter intake, average daily gain and ultra-sound scanning of carcass subcutaneous fat thickness upon Longissimus (12 th rib) and Biceps femoris muscle and rib eye area. Other four steers were randomly allotted to one of the treatments in a 4 x 4 latin square design in order to assess digestibility of dry matter, crude protein, neutral detergent fiber and acid detergent fiber fractions of the diet. There were no effects of additives on dry matter intake and rate of growth of carcass fat thickness and rib eye area. Yeast culture tended to decrease average daily gain and increase feed conversion (p<0.10). Digestibility was not affected by treatments (p>0.10). Supplementation of live yeast culture, monensin or the combination of both may not be important on finishing beef steers fed high grain diets in feedlot., Foi avaliado o efeito da adição de cultura de leveduras vivas (Saccharomyces cerevisiae, cepa 1026), da monensina e da combinação dos dois aditivos em dietas de alto concentrado, sobre as características de desempenho de novilhos confinados e sobre a digestibilidade aparente da dieta. Novilhos Nelore (339 kg PV, 20 meses de idade, n= 72) foram alimentados por 84 dias com uma dieta basal (2,58 Mcal EM/kg MS, 14% PB) sem aditivos (controle) ou suplementada com levedura (0,6 g de Beef Sacc®/kg de matéria seca), monensina (0,3 g de Rumensin®/kg de matéria seca) ou a adição de ambos aditivos para avaliar o desempenho em confinamento por meio da mensuração individual do consumo, ganho de peso e medidas de ultra-som da espessura de gordura subcutânea nos músculos Longissimus (12a costela) e Biceps femoris. Outros quatro novilhos foram designados aleatoriamente aos tratamentos seguindo um delineamento em quadrado latino a fim de determinar os efeitos dos tratamentos sobre a digestibilidade aparente da matéria seca, proteína bruta, fibra em detergente neutro e ácido da dieta. Não houve efeitos dos aditivos sobre o consumo de matéria seca e na taxa de aumento da espessura de gordura subcutânea e em área do músculo Longissimus, entretanto, a levedura tendeu a diminuir o ganho de peso médio diário e aumentar a conversão alimentar (p<0,10). Os coeficientes de digestibili- dade aparente das frações estudadas não foram influenciados pela adição dos aditivos na dieta (p>0,10). A adição de leveduras vivas, monensina ou da combinação de ambos pode não ser impor- tante sobre a terminação de bovinos de corte confinados com dieta de alto concentrado.

The effect of adding live yeast culture (Saccharomyces cerevisiae, strain 1026), monensin or the combination of both additives to high grain diets on feedlot performance and digestibility of steers, was studied. Nellore steers (n= 72, 339 kg BW, 20 months-old) were fed for 84 days a basal ration (2.58 Mcal EM/kg DM, 14% CP) without additives (control), or with yeast culture (0.6 g Beef Sacc®/ kg DM), monensin (0.3 g Rumensin®/ kg DM) or the combination of both additives to evaluate feedlot performance through individual measurements of dry matter intake, average daily gain and ultra-sound scanning of carcass subcutaneous fat thickness upon Longissimus (12 th rib) and Biceps femoris muscle and rib eye area. Other four steers were randomly allotted to one of the treatments in a 4 x 4 latin square design in order to assess digestibility of dry matter, crude protein, neutral detergent fiber and acid detergent fiber fractions of the diet. There were no effects of additives on dry matter intake and rate of growth of carcass fat thickness and rib eye area. Yeast culture tended to decrease average daily gain and increase feed conversion (p<0.10). Digestibility was not affected by treatments (p>0.10). Supplementation of live yeast culture, monensin or the combination of both may not be important on finishing beef steers fed high grain diets in feedlot., Foi avaliado o efeito da adição de cultura de leveduras vivas (Saccharomyces cerevisiae, cepa 1026), da monensina e da combinação dos dois aditivos em dietas de alto concentrado, sobre as características de desempenho de novilhos confinados e sobre a digestibilidade aparente da dieta. Novilhos Nelore (339 kg PV, 20 meses de idade, n= 72) foram alimentados por 84 dias com uma dieta basal (2,58 Mcal EM/kg MS, 14% PB) sem aditivos (controle) ou suplementada com levedura (0,6 g de Beef Sacc®/kg de matéria seca), monensina (0,3 g de Rumensin®/kg de matéria seca) ou a adição de ambos aditivos para avaliar o desempenho em confinamento por meio da mensuração individual do consumo, ganho de peso e medidas de ultra-som da espessura de gordura subcutânea nos músculos Longissimus (12a costela) e Biceps femoris. Outros quatro novilhos foram designados aleatoriamente aos tratamentos seguindo um delineamento em quadrado latino a fim de determinar os efeitos dos tratamentos sobre a digestibilidade aparente da matéria seca, proteína bruta, fibra em detergente neutro e ácido da dieta. Não houve efeitos dos aditivos sobre o consumo de matéria seca e na taxa de aumento da espessura de gordura subcutânea e em área do músculo Longissimus, entretanto, a levedura tendeu a diminuir o ganho de peso médio diário e aumentar a conversão alimentar (p<0,10). Os coeficientes de digestibili- dade aparente das frações estudadas não foram influenciados pela adição dos aditivos na dieta (p>0,10). A adição de leveduras vivas, monensina ou da combinação de ambos pode não ser impor- tante sobre a terminação de bovinos de corte confinados com dieta de alto concentrado.

In tropical regions, Gyr and Guzerat breeds (Bos indicus) are most explored for dairy industry and are much more adapted to climate. Gyr and Guzerat are Zebu breeds very common in Brazil and they are being used to generate Bos taurus x Bos indicus crosses in order to combine good production, heat and parasite tolerance on the tropics. Breeding programs for the main economically important traits of Zebu dairy cattle have been recently introduced in Brazil and is based on the use of genetically superior sires in the herds. A major objective of QTL (Quantitative Trait Loci) and candidate genes is to find genes and markers that can be implemented in breeding programs across marker assisted selection (MAS). In Zebu dairy cattle MAS could be used to pre-select young candidate bulls to progeny testing, thus increasing selection differentials, shortening generation interval and increasing genetic gain, En regiones tropicales, las razas bovinas Gyr y Guzerat, pertenecientes a la subespecie Bos indicus, son las más exploradas en la industria lechera, entre otras razones, porque están más adaptadas al clima tropical. Gyr y Guzerat son razas cebuinas comunes en Brasil, y son utilizadas para generar las razas sintéticas Gyrolando (5/8 Holstein: 3/8 Gyr) y Guzolando (5/8 Holstein: 3/8 Guzerat), en orden a combinar una buena producción y tolerancia al calor y los parásitos en el trópico. Programas de mejoramiento para las características de importancia económica en cebú lechero, han sido introducidos recientemente en Brasil, basados en el uso de reproductores genéticamente superiores de los diferentes rebaños. El principal objetivo de QTL (loci de características cuantitativas) y genes candidatos, es encontrar genes y marcadores que puedan ser implementados en programas de mejoramiento a través de la selección asistida por marcadores (MAS). En cebuinos lecheros, la selección asistida por marcadores puede ser usada para preseleccionar toros candidatos jóvenes para pruebas de progenie, incrementando así, el diferencial de selección, reducción del intervalo generacional e incrementando el mérito genético.

In tropical regions, Gyr and Guzerat breeds (Bos indicus) are most explored for dairy industry and are much more adapted to climate. Gyr and Guzerat are Zebu breeds very common in Brazil and they are being used to generate Bos taurus x Bos indicus crosses in order to combine good production, heat and parasite tolerance on the tropics. Breeding programs for the main economically important traits of Zebu dairy cattle have been recently introduced in Brazil and is based on the use of genetically superior sires in the herds. A major objective of QTL (Quantitative Trait Loci) and candidate genes is to find genes and markers that can be implemented in breeding programs across marker assisted selection (MAS). In Zebu dairy cattle MAS could be used to pre-select young candidate bulls to progeny testing, thus increasing selection differentials, shortening generation interval and increasing genetic gain, En regiones tropicales, las razas bovinas Gyr y Guzerat, pertenecientes a la subespecie Bos indicus, son las más exploradas en la industria lechera, entre otras razones, porque están más adaptadas al clima tropical. Gyr y Guzerat son razas cebuinas comunes en Brasil, y son utilizadas para generar las razas sintéticas Gyrolando (5/8 Holstein: 3/8 Gyr) y Guzolando (5/8 Holstein: 3/8 Guzerat), en orden a combinar una buena producción y tolerancia al calor y los parásitos en el trópico. Programas de mejoramiento para las características de importancia económica en cebú lechero, han sido introducidos recientemente en Brasil, basados en el uso de reproductores genéticamente superiores de los diferentes rebaños. El principal objetivo de QTL (loci de características cuantitativas) y genes candidatos, es encontrar genes y marcadores que puedan ser implementados en programas de mejoramiento a través de la selección asistida por marcadores (MAS). En cebuinos lecheros, la selección asistida por marcadores puede ser usada para preseleccionar toros candidatos jóvenes para pruebas de progenie, incrementando así, el diferencial de selección, reducción del intervalo generacional e incrementando el mérito genético.

Tick resistant cattle could provide a potentially sustainable and environmentally sound method of controlling cattle ticks. Advances in genomics and the availability of the bovine genome sequence open up opportunities to identify useful and selectable genes controlling cattle tick resistance. Using quantitative real-time PCR and the Affymetrix bovine array platform, differences in gene expression of skin biopsies from tick resistant Bos indicus (Brahman) and tick susceptible Bos taurus (Holstein-Friesian) cattle following tick challenge were examined. We identified 138 significant differentially-expressed genes, including several immunological/host defence genes, extracellular matrix proteins, and transcription factors as well as genes involved in lipid metabolism. Three key pathways, represented by genes differentially expressed in resistant Brahmans, were identified; the development of the cell-mediated immune response, structural integrity of the dermis and intracellular Ca2+ levels. Ca2+, which is implicated in host responses to microbial stimuli, may be required for the enhancement or fine-tuning of transcriptional activation of Ca2+-dependant host defence signalling pathways.

The aim of this work was to value the daily gain and the weight of the weaned of calves of Bos taurus it crosses it with Bos indicus in a proportion from ¼ to ¾ approximately, the registrations of 302 calves were used, which were managed under conditions of conventional care husbandry. The races Bos taurus used for cross them were Belgian blue, Charolais, Limousine and Beef master; the Bos indicus, was Brahman, Nelore, Indobrasil and Simbrah. The studied variables were, weight to the birth (WB), weigh to weaning (WW), which was carried out to the four months of age and the daily gain of weight (DGW). The results were analyzed by means of descriptive statistic of central tendency where for the pesos to the birth presented an average of 50.8 Kg, with variation of 20 to 77 Kg. The weight to the weaning showed an average of 175 Kg, with variation of 132 to 256 Kg with better results when crossed with of Belgian blue with Brahman and Charolais with Simbrah, respectively. The daily gain of weight showed an average of 1.15 Kg, with variation of 0.820 to 1.85 Kg. In conclusion, one can say that it crosses it of Bos tarurus with Bos indicus , it can be an alternative for the production of bovine for meat in humid tropic., El objetivo del trabajo fue evaluar la ganancia diaria de peso desde el nacimiento hasta el destete a los cuatro meses de edad de terneros de la cruza Bos taurus con Bos indicus, manejados en pastoreo convencional, para lo cual se utilizaron los registros de 302 terneros. Las razas Bos taurus utilizadas para las cruzas fueron Belgian blue, Charolais, Limousine y Beef master; las Bos indicus, fueron Brahman, Nelore, Indobrasil y Simbrah. Los resultados se analizaron mediante estadística descriptiva de tendencia central, donde para los pesos al nacimiento presentaron un promedio de 50.8 Kg., con una variación de 20 a 77 Kg. El peso al destete mostró un promedio de 175 Kg., con una variación de 132 a 256 Kg., observándose mejores pesos para las cruzas de Belgian blue con Brahman y Charolais con Simbrah, respectivamente. La ganancia diaria de peso mostró un promedio de 1.15 Kg., con variación de 0.820 a 1.85 Kg. En conclusión, la cruza de Bos tarurus con Bos indicus, puede ser una alternativa para la producción de bovinos para carne en trópico húmedo.

The aim of this work was to value the daily gain and the weight of the weaned of calves of Bos taurus it crosses it with Bos indicus in a proportion from ¼ to ¾ approximately, the registrations of 302 calves were used, which were managed under conditions of conventional care husbandry. The races Bos taurus used for cross them were Belgian blue, Charolais, Limousine and Beef master; the Bos indicus, was Brahman, Nelore, Indobrasil and Simbrah. The studied variables were, weight to the birth (WB), weigh to weaning (WW), which was carried out to the four months of age and the daily gain of weight (DGW). The results were analyzed by means of descriptive statistic of central tendency where for the pesos to the birth presented an average of 50.8 Kg, with variation of 20 to 77 Kg. The weight to the weaning showed an average of 175 Kg, with variation of 132 to 256 Kg with better results when crossed with of Belgian blue with Brahman and Charolais with Simbrah, respectively. The daily gain of weight showed an average of 1.15 Kg, with variation of 0.820 to 1.85 Kg. In conclusion, one can say that it crosses it of Bos tarurus with Bos indicus , it can be an alternative for the production of bovine for meat in humid tropic., El objetivo del trabajo fue evaluar la ganancia diaria de peso desde el nacimiento hasta el destete a los cuatro meses de edad de terneros de la cruza Bos taurus con Bos indicus, manejados en pastoreo convencional, para lo cual se utilizaron los registros de 302 terneros. Las razas Bos taurus utilizadas para las cruzas fueron Belgian blue, Charolais, Limousine y Beef master; las Bos indicus, fueron Brahman, Nelore, Indobrasil y Simbrah. Los resultados se analizaron mediante estadística descriptiva de tendencia central, donde para los pesos al nacimiento presentaron un promedio de 50.8 Kg., con una variación de 20 a 77 Kg. El peso al destete mostró un promedio de 175 Kg., con una variación de 132 a 256 Kg., observándose mejores pesos para las cruzas de Belgian blue con Brahman y Charolais con Simbrah, respectivamente. La ganancia diaria de peso mostró un promedio de 1.15 Kg., con variación de 0.820 a 1.85 Kg. En conclusión, la cruza de Bos tarurus con Bos indicus, puede ser una alternativa para la producción de bovinos para carne en trópico húmedo.

Four experiments were performed to study the kinetics of purine metabolism and urinary excretion in Zebu crossbred cattle. Fasting excretion was established in Expt 1, using eighteen male Bos indicus x Bos taurus crossbred cattle (261 (SE 9.1) kg body weight), six of each of the following genotypes: 5/8 Bos indicus, 1/2 Bos indicus and 3/8 Bos indicus. No significant differences were observed among genotypes in fasting purine derivative excretion (277.3 (SE 35.43) micromol/metabolic body weight). In a second experiment we measured the xanthine oxidase activity, which was higher in liver than in duodenal mucosa (0.64 and 0.06 (SE 0.12) units/g wet tissue per min respectively; P>0.05) being in plasma 0.60 (SE 0.36) units/l per min. The kinetics of uric acid were measured by intravenous pulse dose of [1,3-15N]uric acid (Expt 3). The cumulative recovery of the isotope in urine was 82 (SE 6.69) %, and uric acid plasma removal, pool size and mean retention time were 0.284 (SE 0.051) per h, 5.45 (SE 0.823) mmol and 3.52 (SE 0.521) h, respectively. Allantoin was removed from plasma at an estimated fractional rate of 0.273 (SE 0.081) per h and mean retention was 3.66 (SE 1.08) h. In Expt 4, the relationship between urinary purine derivative excretion (Y; mmol/d) and digestible organic matter intake (X, kg/d) was defined by the equation: Y=7.69 (SE 4.2)+5.69 (SE 1.68) X; n 16, Se 1.31, r 0.67.

En una zona de bosque húmedo tropical del municipio de Caucasia (Antioquia) se seleccionaron dos explotaciones para caracterizar el comportamiento productivo y reproductivo del ganado Brahman mestizo: la hacienda La Leyenda con una extensión de 2500 hectáreas y la hacienda La Candelaria con una extensión de 264.5 hectáreas; de las cuales se tomaron todos los registros de peso al nacimiento, peso al destete, edad al primer parto e intervalo entre partos, durante los años 1990 a mayo de 1998. Los datos se sometieron a análisis de stepwise para determinar las variables que tuvieron efecto en los parámetros evaluados y luego se sometieron a análisis de varianza multifactorial. Se obtuvo un peso promedio al nacimiento de 30.89 kg para la hacienda La Candelaria y de 32.02 kg para la hacienda La Leyenda. En La Candelaria el análisis de varianza mostró efecto significativo (P<0.01) para las variables mes de nacimiento y padre y en La Leyenda mostró efecto significativo (P<0.01) para la variable año de nacimiento. El peso al destete ajustado a 240 días obtenido para la hacienda La Candelaria fue de 168.05 kg y para la hacienda La Leyenda de 175.66 kg; el análisis de varianza mostró efecto significativo para mes (P<0.05) y año de nacimiento y sexo (P<0.01), en La Candelaria y efecto significativo (P<0.01) para mes y año de nacimiento, sexo y padre en la hacienda La Leyenda. Para el parámetro reproductivo edad al primer parto, el promedio fue de 43.8 meses para la hacienda La Candelaria y 40.1 meses en la hacienda La Leyenda; el análisis de varianza mostró efecto significativo del año de entrada a servicio (P<0.01) y del peso de entrada (P<0.05) en ambas haciendas. El intervalo entre partos promedio encontrado fue de 439.85 días en la hacienda La Candelaria y de 462.25 días en la hacienda La Leyenda ; el análisis de varianza mostró efecto significativo (P<0.01) para año de nacimiento y número de parto en la hacienda La Candelaria y en la hacienda La Leyenda tuvieron efecto sig