Estimate of genetic and non-genetic parameters and trends for age at first calving in Sahiwal cows

Abstract

Age at first calving (AFC) records (403) of Sahiwal cows sired by 30 bulls, spread over 50 years (1948–1997) maintained at Government Cattle Breeding Farm, Anjora, Durg were utilized to study the factors affecting age at first calving and its estimate of heritability by using least squares technique. The period of birth and sire effects were significant and the season was nonsignificant. The estimate of heritability was moderate (0.43). AFC showed negative association with first lactation milk yield, however, the relationship was positive in later cumulative milk and lifetime traits. Overall phenotypic and genetic trends for AFC were in the desired direction, except poor performance in the second to fourth periods. Genetic trend can further be improved if the available additive genetic variability in the herd is properly exploited through selection.