RESUMO
Many factors can influence milk yield. Among them are included the environmental, genetics factors and gene-environment interaction. Studies aiming to identify the magnitude of these factors are needed. The effect of calf sex on milk yield is controversial. Therefore, the objective of this work was to investigate the influence of calf gender on milk production along the lactation (P305) of Gyr cows. Data of 18,898 lactation records between the years of 1987 to 2013 were acquired in the official milk control of Brazilian Association of Zebu Breeders (ABCZ) database and analyzed by the least squares method. The linear model for P305 included the fixed effects of calf sex, contemporary group and age of cow at calving within the calf sex as co-variable linear and quadratic. Significant difference was found for the sex of the calf (P 0.01) and the adjusted means of P305 of cows that gave birth to male and female calves were, respectively, 3,565.6 and 3,492.3 kg. Also, there was significant effect of the age of the cow at calving nested within sex of the calf (P 0.01). For female calves the linear and quadratic regression coefficients for the cow age at calving were 17.32 and -0.077 kg, respectively. When the calves were male these coefficients were 21.23 and -0.098 kg, describing a quadratic relation which the production peak was observed at 104 months of age. Hence, Gyr cows
O artigo não apresenta resumo em português.
RESUMO
Many factors can influence milk yield. Among them are included the environmental, genetics factors and gene-environment interaction. Studies aiming to identify the magnitude of these factors are needed. The effect of calf sex on milk yield is controversial. Therefore, the objective of this work was to investigate the influence of calf gender on milk production along the lactation (P305) of Gyr cows. Data of 18,898 lactation records between the years of 1987 to 2013 were acquired in the official milk control of Brazilian Association of Zebu Breeders (ABCZ) database and analyzed by the least squares method. The linear model for P305 included the fixed effects of calf sex, contemporary group and age of cow at calving within the calf sex as co-variable linear and quadratic. Significant difference was found for the sex of the calf (P 0.01) and the adjusted means of P305 of cows that gave birth to male and female calves were, respectively, 3,565.6 and 3,492.3 kg. Also, there was significant effect of the age of the cow at calving nested within sex of the calf (P 0.01). For female calves the linear and quadratic regression coefficients for the cow age at calving were 17.32 and -0.077 kg, respectively. When the calves were male these coefficients were 21.23 and -0.098 kg, describing a quadratic relation which the production peak was observed at 104 months of age. Hence, Gyr cows
O artigo não apresenta resumo em português.
RESUMO
The 90 days weight from 814 Holstein calves was studied. They were born though out 19 years. The average live weight was 85.0 ± 10.5 kg; 88.1 kg for male and 83.0 for female. They regressional model includ effects of year and month of birth., sex, gestation lenght and cow age and respond for 32.63% the variation year and sex were the more importants factors and the interation was not important. The bighests weights was for the births from january to march, for gestation of 280 to 300 days and for cows of 7 to 9 years. The heritability estmates for 90 days weigth was 0.36 ± 0.11 and indicate the possible improvement by selection.
Foi estudado o peso aos 90 dias de idade de 814 bezerros holandeses preto e branco nascidos em período de 19 anos. O peso médio observado foi de 85,0 ± 10,5 kg sendo 88,1 kg para os machos e 83,0 para as fêmeas. O modelo de regressão que continha os efeitos de ano e mês de nascimento, sexo, período de gestação e idade da vaca explicou 32,63% da variação ocorrida. Ano e sexo e bezerro foram os fatores de meio mais importantes e, as interações foram de pequena expressão e não consideradas. Os maiores pesos aos 90 dias foram encontrados para os nascimentos ocorridos de janeiro a março, para as gestações de 280 a 300 dias e para as vacas de 7 a 9 anos. O coeficiente de herdabilidade para o peso aos 90 dias foi estimado em 0,36 ± 0,11 pelo método de correlação entre meio-irmãos paternos, indicando a possibilidade de melhoramento da característica por seleção.
RESUMO
The objective of this study was to evaluate the factors affecting the performance of black and white Holstein calves, at 180 days of weight, raised under artificial milking conditions, at the Experimental Farm in the State of São Paulo (Brazil). A total of 814 calves (389 males and 425 females) with a mean weight of 136.8kg, born from 1945 to 1963, were used. The animals were represented by 54 groups of paternal half-sibs. The environmental effects were submitted to a multiple regression analysis. Year of birth was the most significant source of variation of weight followed by sex of the calf and gestation period. Interactions between these factors were not significant. The equation obtained for weight at 180 days of age () in function of year of birth (a and a2), sex of the calf (s) and gestation period (g and g2), with a determination coefficient of 32.43%, was given as follows: = -1,070.7500 - 2.178a + 0.0014 a2 + 8.5933 pg - 0.00148 pg2 - 9.3541s. Mean weights of the calves decreased curvilinearly from 1945 to 1963, showing a difference of 38.7kg among the estimated weights of these years. Male calves were 9.4kg heavier than female calves. Ninety-two percent of the data on gestation period were obtained during the interval from 271 to 280 days. Weight of the calves showed a positive curvilinear response to the increase of the gestation period. Heritability values estimat
Foram estudados pesos aos 180 dias, de 389 machos e 425 fêmeas da raça Holandesa Preta e Branca, filhos de 54 touros e nascidos de 1945 a 1963 na Estação Experimental de Zootecnia de Pindamonhangaba. A equação encontrada para o peso aos 180 dias de idade (), em função de ano de nascimento (a e a2), sexo(s), período de gestação (g e g2), com coeficiente de determinação de 32,43%, foi a seguinte: = -1.070,7500 - 2,1780a + 0,0014a2 + 8,5933 g - 0,0014 g2 - 9,3541 s. O peso médio foi de 136,8 kg com diferença de 9,4 kg entre machos e fêmeas. Ano de nascimento foi o principal efeito, seguido de sexo. O período de gestação foi o terceiro fator em importância, apresentando peso de 137,2 kg para os períodos de gestação de 271 a 275 dias e de 136,6 kg para os de 276 a 280 dias. Mês de nascimento, procedência do touro, idade da mãe e interações não foram incluídos por participarem com menos de 1% da variação do peso aos 180 dias. A estimativa de herdabilidade para o peso aos 180 dias foi de 0,612, com intervalo de confiança entre 0,332 a 0,892 ao nível de 95% de probabilidade, o que permite apreciável ganho genético por seleção.
RESUMO
The objective of this study was to evaluate the factors affecting the performance of black and white Holstein calves, at 180 days of weight, raised under artificial milking conditions, at the Experimental Farm in the State of São Paulo (Brazil). A total of 814 calves (389 males and 425 females) with a mean weight of 136.8kg, born from 1945 to 1963, were used. The animals were represented by 54 groups of paternal half-sibs. The environmental effects were submitted to a multiple regression analysis. Year of birth was the most significant source of variation of weight followed by sex of the calf and gestation period. Interactions between these factors were not significant. The equation obtained for weight at 180 days of age () in function of year of birth (a and a2), sex of the calf (s) and gestation period (g and g2), with a determination coefficient of 32.43%, was given as follows: = -1,070.7500 - 2.178a + 0.0014 a2 + 8.5933 pg - 0.00148 pg2 - 9.3541s. Mean weights of the calves decreased curvilinearly from 1945 to 1963, showing a difference of 38.7kg among the estimated weights of these years. Male calves were 9.4kg heavier than female calves. Ninety-two percent of the data on gestation period were obtained during the interval from 271 to 280 days. Weight of the calves showed a positive curvilinear response to the increase of the gestation period. Heritability values estimat
Foram estudados pesos aos 180 dias, de 389 machos e 425 fêmeas da raça Holandesa Preta e Branca, filhos de 54 touros e nascidos de 1945 a 1963 na Estação Experimental de Zootecnia de Pindamonhangaba. A equação encontrada para o peso aos 180 dias de idade (), em função de ano de nascimento (a e a2), sexo(s), período de gestação (g e g2), com coeficiente de determinação de 32,43%, foi a seguinte: = -1.070,7500 - 2,1780a + 0,0014a2 + 8,5933 g - 0,0014 g2 - 9,3541 s. O peso médio foi de 136,8 kg com diferença de 9,4 kg entre machos e fêmeas. Ano de nascimento foi o principal efeito, seguido de sexo. O período de gestação foi o terceiro fator em importância, apresentando peso de 137,2 kg para os períodos de gestação de 271 a 275 dias e de 136,6 kg para os de 276 a 280 dias. Mês de nascimento, procedência do touro, idade da mãe e interações não foram incluídos por participarem com menos de 1% da variação do peso aos 180 dias. A estimativa de herdabilidade para o peso aos 180 dias foi de 0,612, com intervalo de confiança entre 0,332 a 0,892 ao nível de 95% de probabilidade, o que permite apreciável ganho genético por seleção.
RESUMO
The 90 days weight from 814 Holstein calves was studied. They were born though out 19 years. The average live weight was 85.0 ± 10.5 kg; 88.1 kg for male and 83.0 for female. They regressional model includ effects of year and month of birth., sex, gestation lenght and cow age and respond for 32.63% the variation year and sex were the more importants factors and the interation was not important. The bighests weights was for the births from january to march, for gestation of 280 to 300 days and for cows of 7 to 9 years. The heritability estmates for 90 days weigth was 0.36 ± 0.11 and indicate the possible improvement by selection.
Foi estudado o peso aos 90 dias de idade de 814 bezerros holandeses preto e branco nascidos em período de 19 anos. O peso médio observado foi de 85,0 ± 10,5 kg sendo 88,1 kg para os machos e 83,0 para as fêmeas. O modelo de regressão que continha os efeitos de ano e mês de nascimento, sexo, período de gestação e idade da vaca explicou 32,63% da variação ocorrida. Ano e sexo e bezerro foram os fatores de meio mais importantes e, as interações foram de pequena expressão e não consideradas. Os maiores pesos aos 90 dias foram encontrados para os nascimentos ocorridos de janeiro a março, para as gestações de 280 a 300 dias e para as vacas de 7 a 9 anos. O coeficiente de herdabilidade para o peso aos 90 dias foi estimado em 0,36 ± 0,11 pelo método de correlação entre meio-irmãos paternos, indicando a possibilidade de melhoramento da característica por seleção.