Estimation of variance components for female longevity in Australian Angus cattle using random regression models

Abstract

Cow longevity is an economically important trait for beef cattle breeding. In this study, random regression models were used to estimate genetic parameters for female longevity in Australian Angus cattle. Longevity was defined using 10 binary records (0 for ‘not in the breeding herd’ and 1 for ‘active in the breeding herd’) between age 2 to 11. A Bayesian random regression model was fitted separately to 5 different groups of disposal reasons supplied by breeders. The heritability estimates were generally low with peaks ranging from 0.03 to 0.12. The highest and lowest heritability estimates were obtained for performance and fertility datasets, respectively. Genetic correlations were high between ages 3 to 5 and age 6 for all groups except for the structural problems group in which age 3 showed a low genetic correlation. This illustrates that selection for longevity could be undertaken early in cow’s life.