RESUMO
ABSTRACT: Longevity is an important trait due to its relationship with profitability. Type traits have been used as indirect predictors for productive life. The objective of this study was to evaluate the relationship of 20 type traits on length of productive life in Brazilian Holsteins, using a piecewise Weibull proportional hazard model. Three analyses were performed i) productive life was corrected for within herd level of production as a proxy for functional longevity, which included the time-dependent effects of region within year, class of milk production within herdyear, milk production class within lactation number, fat class and protein contents within herd and (variation in) herd size as well as the time-independent fixed effect of age at first calving and the type trait score; ii) the effects related to production were omitted from the first model (true longevity) and iii) with the first model, the effect of type was also studied considering five classes of percentage of type-scored cows within the herd. All analyses were performed using the Survival Kit program. The final score, angularity, top line, udder texture and suspensory ligament showed the strongest relationship with productive life. When type traits were available only for a small fraction of the herd, the cows had a better chance of remaining longer in the herd. The absence of type trait phenotypes was associated with a strong increase of culling risk for the cows. Type traits were not found to be good indirect predictors of productive life in Brazil.
RESUMO
ABSTRACT: Longevity is an important trait due to its relationship with profitability. Type traits have been used as indirect predictors for productive life. The objective of this study was to evaluate the relationship of 20 type traits on length of productive life in Brazilian Holsteins, using a piecewise Weibull proportional hazard model. Three analyses were performed i) productive life was corrected for within herd level of production as a proxy for functional longevity, which included the time-dependent effects of region within year, class of milk production within herdyear, milk production class within lactation number, fat class and protein contents within herd and (variation in) herd size as well as the time-independent fixed effect of age at first calving and the type trait score; ii) the effects related to production were omitted from the first model (true longevity) and iii) with the first model, the effect of type was also studied considering five classes of percentage of type-scored cows within the herd. All analyses were performed using the Survival Kit program. The final score, angularity, top line, udder texture and suspensory ligament showed the strongest relationship with productive life. When type traits were available only for a small fraction of the herd, the cows had a better chance of remaining longer in the herd. The absence of type trait phenotypes was associated with a strong increase of culling risk for the cows. Type traits were not found to be good indirect predictors of productive life in Brazil.
RESUMO
The effects of sire-environment interaction on genetic evaluation were investigated by analyzing 108,702 records of milk yield (305ME) of Holstein cows from the states of Minas Gerais, São Paulo, Paraná, Santa Catarina and Rio Grande do Sul. A Multivariate animal model was applied to estimate of genetic variance and covariance components, using Gibbs sampling. The a posteriori means of genetic variance in Santa Catarina and Rio Grande do Sul were higher (p 0.001) than estimates in others states, even though the estimates did not vary (p > 0.05) between these two states. Heritability estimates of states ranged from 0.24 to 0.38. Genetic correlations among states were low and ranged from 0.07 to 0.33. Spearmans correlation among sire breeding values ranged from 0.73 to 0.86. These results suggest sire-environment interaction for 305ME in the states of Minas Gerais, São Paulo, Paraná and between the states of Santa Catarina and Rio Grande do Sul.
Os efeitos, sobre a avaliação genética da interação reprodutor-região, foram investigados analisando-se 108.702 registros de produção de leite (PL305) de vacas da raça Holandesa, pertencentes a rebanhos de Minas Gerais, São Paulo, Paraná, Sanata Catarina e Rio Grande do Sul. Um modelo animal multicarácter foi aplicado para estimar os componentes de variância e covariância utilizando amostragem de Gibbs. As médias a posteriori da variância genética de Santa Catarina e Rio Grande do Sul foram superiores (p 0,001) às estimadas nos demais estados e iguais (p > 0,05) entre si. As herdabilidades variaram entre 0,24 e 0,38. As correlações genéticas entre os estados foram de baixa magnitude e variaram entre 0,07 a 0,33. Os valores de correlação de Spearman entre os valores genéticos dos reprodutores variaram entre 0,73 e 0,86. Os resultados sugerem a existência da interação genótipo-ambiente para PL305 entre os estados de Minas Gerais, São Paulo, Paraná e os estados de Santa Catarina e Rio Grande do Sul.
RESUMO
The effects of sire-environment interaction on genetic evaluation were investigated by analyzing 108,702 records of milk yield (305ME) of Holstein cows from the states of Minas Gerais, São Paulo, Paraná, Santa Catarina and Rio Grande do Sul. A Multivariate animal model was applied to estimate of genetic variance and covariance components, using Gibbs sampling. The a posteriori means of genetic variance in Santa Catarina and Rio Grande do Sul were higher (p 0.001) than estimates in others states, even though the estimates did not vary (p > 0.05) between these two states. Heritability estimates of states ranged from 0.24 to 0.38. Genetic correlations among states were low and ranged from 0.07 to 0.33. Spearmans correlation among sire breeding values ranged from 0.73 to 0.86. These results suggest sire-environment interaction for 305ME in the states of Minas Gerais, São Paulo, Paraná and between the states of Santa Catarina and Rio Grande do Sul.
Os efeitos, sobre a avaliação genética da interação reprodutor-região, foram investigados analisando-se 108.702 registros de produção de leite (PL305) de vacas da raça Holandesa, pertencentes a rebanhos de Minas Gerais, São Paulo, Paraná, Sanata Catarina e Rio Grande do Sul. Um modelo animal multicarácter foi aplicado para estimar os componentes de variância e covariância utilizando amostragem de Gibbs. As médias a posteriori da variância genética de Santa Catarina e Rio Grande do Sul foram superiores (p 0,001) às estimadas nos demais estados e iguais (p > 0,05) entre si. As herdabilidades variaram entre 0,24 e 0,38. As correlações genéticas entre os estados foram de baixa magnitude e variaram entre 0,07 a 0,33. Os valores de correlação de Spearman entre os valores genéticos dos reprodutores variaram entre 0,73 e 0,86. Os resultados sugerem a existência da interação genótipo-ambiente para PL305 entre os estados de Minas Gerais, São Paulo, Paraná e os estados de Santa Catarina e Rio Grande do Sul.