RESUMO
The main objective of this study was to investigate genetic and phenotypic trends for fertility traits in Holstein dairy population under warm and temperate climate. Fertility traits were: success in first service, gestation length, number of inseminations, insemination outcome, calving interval, calving birth weight and days open. The edited data set included up to 23,402 records from 9,486 cows. The mean and standard deviation for fertility traits were 0.32 ± 0.003, 278.2 ± 5.58, 2.73 ± 1.94,0.31 ± 0.001, 415.99 ± 79.62, 40.4 ± 6.08 and 140.36 ± 76.16 for success in first service, gestation length, number of inseminations, insemination outcome, calving interval, calving birth weight and days open, respectively. In general, there were decreasing genetic trends for all traits over the years. On the other hand, there were decreasing phenotypic trend for days open, calving interval, gestation length, number of inseminations and calving birth weight, but estimates of phenotypic trends were positive for success in first service and insemination outcome over the years. It was concluded decreased trend for days open, calving interval, gestation length, number of inseminations and calving birth weight and increased trend for success in first service and insemination outcome traits over time indicated that Holstein dairy producers in warm and temperate climate were successful in managing and improving in nutrition during 1999 to 2013> (AU)
Assuntos
Animais , Bovinos , Bovinos , Fenótipo , Fenômenos Genéticos/genética , Clima TemperadoRESUMO
The main objective of this study was to investigate genetic and phenotypic trends for fertility traits in Holstein dairy population under warm and temperate climate. Fertility traits were: success in first service, gestation length, number of inseminations, insemination outcome, calving interval, calving birth weight and days open. The edited data set included up to 23,402 records from 9,486 cows. The mean and standard deviation for fertility traits were 0.32 ± 0.003, 278.2 ± 5.58, 2.73 ± 1.94,0.31 ± 0.001, 415.99 ± 79.62, 40.4 ± 6.08 and 140.36 ± 76.16 for success in first service, gestation length, number of inseminations, insemination outcome, calving interval, calving birth weight and days open, respectively. In general, there were decreasing genetic trends for all traits over the years. On the other hand, there were decreasing phenotypic trend for days open, calving interval, gestation length, number of inseminations and calving birth weight, but estimates of phenotypic trends were positive for success in first service and insemination outcome over the years. It was concluded decreased trend for days open, calving interval, gestation length, number of inseminations and calving birth weight and increased trend for success in first service and insemination outcome traits over time indicated that Holstein dairy producers in warm and temperate climate were successful in managing and improving in nutrition during 1999 to 2013>
Assuntos
Animais , Bovinos , Bovinos , Clima Temperado , Fenótipo , Fenômenos Genéticos/genéticaRESUMO
The aims of the present study were to estimate genetic parameters, as well as phenotypic, genetic and environmental trends for age at first calving (AFC) and calving intervals (CI) on Gyr dairy breed, using a multivariate derivative-free restricted maximum likelihood (MTDFREML) with an animal model. The mathematic model for calving interval included herd-year of calving, calving season, and the covariate age of cow as fixed effects, and animal, and permanent environment as random effects. The model for age at first calving included herd-year of birth and season of birth as fixed effects, and animal as random effect. Through the bivariate analyses, estimates of heritability were: for age at first calving 0.17 and for calving interval 0.06. The estimate of repeatability for calving interval was 0.17. The phenotypic, genetic and environmental correlations between age at first calving and calving interval were 0.06, 0.37 and 0.03, respectively. The phenotypic, genetic and environment annual trends for age at first calving were, respectively, -0.446±0,077 (P 0.01), 0.008±.013 and -0.454 months based on breeding values of cows, and -0.185±0.083 (P 0.05), 0.051±0.059 and -0.236 months based on breeding values of bulls. The phenotypic, genetic and environment annual trends for calving interval were, respectively, -1.25±0.95, -0.98±0.19(P 0.01) and -0,27 days based on breeding values of cows, and -0.88±1.07, -1.62±0.40 (P 0.01) and 0,74 days based on breeding values of bulls.
O objetivo do estudo foi estimar os parâmetros e as tendências fenotípica, genética e ambiental para idade ao primeiro parto (IPP) e intervalo de partos (IDP) na raça Gir, com o emprego de análises uni e bivariadas sob o método da máxima verossimilhança restrita, por meio de algoritmo livre de derivadas (MTDFREML), que ajusta o modelo animal. O modelo matemático adotado para estudo do IDP incluiu os efeitos fixos rebanho-ano de parto, época de parto e idade da vaca ao parto como covariável e os efeitos aleatórios de animal e ambiente permanente. Para a IPP, o modelo incluiu os efeitos fixos rebanho-ano de nascimento e época de nascimento e efeito de animal como aleatório. Por meio de análises bivariadas, as estimativas de herdabilidade foram 0,17 para IPP e 0,06 para IDP. A estimativa de repetibilidade para IDP foi 0,17. As correlações fenotípica, genética e de ambiente entre IPP e IDP foram, respectivamente, 0,06, 0,37 e 0,03. As mudanças anuais fenotípica, genética e de ambiente para IPP foram, respectivamente, -0,446±0,077 (P 0,01), 0,008±0,013 e -0,454 meses, com base no valor genético das vacas, e -0,185± 0,083 (P 0,05), 0,051± 0,059 e -0,236 meses com base no valor genético dos touros. As mudanças anuais fenotípica, genética e de ambiente para IDP foram, respectivamente, -1,25±0,95, -0,98±0,19 (P 0,01) e -0,27 dias com base no valor genético das vacas e -0,88±1,07, -1,62±0,40 (P 0,01) e 0,74 dias, com base no valor genético dos touros.