Use of test day milk yield records for genetic evaluation in Sahiwal cattle.

Abstract

Test day milk yield (TMY) records from the first three lactations were used to estimate genetic and phenotypic parameters in the Sahiwal cattle in Kenya, using animal models in multivariate analyses. In the first analysis, a multivariate repeatability model was used where the TMY records within lactation were considered as repeated traits and the three lactations treated as separate traits. In this case, heritability estimates ranged from 0.22 to 0.30 and were highest in lactation two. In the second analysis, eight TMY in the three lactations were considered as separate traits. In this case heritability estimates ranged from 0.25 to 0.30 and genetic correlations among TMY ranged from 0.34 to 0.68. The results of this study show that TMY could be used in genetic evaluation in Sahiwal cattle.