Genetic parameters for milk yield and reproduction traits in the Chilean Dairy Overo Colorado cattle breed

Abstract

The objective of this study was to estimate genetic parameters for milk production and reproduction traits, with phenotypic and pedigree information from the Dairy Overo Colorado breed from southern Chile. Single and multi-trait mixed models were used to analyze the data. Analyses were performed using ASReml software. Heritability estimates for milk yield, fat yield, protein yield, fat content, protein content, age at first calving and calving interval, were 0.29, 0.34, 0.30, 0.56, 0.56, 0.01 and 0.002, respectively. Genetic correlations between yield traits were high and positive (≥ 0.81). Genetic correlations of milk yield with fat content (-0.32) and protein content (-0.30) were unfavorable. Genetic correlation estimates between age at first calving and yield traits were negative between -0.71 and -0.29. Phenotypic correlations between calving interval and milk yield traits were slightly positive (0.06-0.09), suggesting a weak relationship between reproduction and yield in this population. Genetic variation is considerable for milk production traits. Genetic improvement for age at first calving and calving interval may be slow, because small differences between animals and low reliabilities are expected for estimated breeding values for these traits due to low heritabilities. The design of an efficient breeding program for yield traits based on artificial insemination for this population is feasible using either progeny testing or genomic breeding value prediction for selecting sires.