GENETIC STUDIES ON COMPONENTS OF FIRST LACTATION AND LIFETIME TRAITS IN SAHIWAL CATTLE

Data on 413 Sahiwal cows maintained at Government Livestock Farm, Hisar during 1977-96
were used. Heritability estimates for age at first calving, first lactation milk yield, first lactation length,
first service period, first dry period, first calving interval and first peak yield were 0.49±0.18,
0.13±0.09, 0.47±0.18, 0.25±0.17, 0.46±0.19 and 0.42±0.16, respectively. Heritability estimates
for lifetime performance traits were found to be high and ranged from 0.40±0.19 (no of days in
milk) to 0.91±0.25 (lifetime milk yield). FLMY had high positive genetic correlations with FLL, FSP,
FCI, and FPY but negative with FDP. The corresponding Phenotypic correlations were also significant
and positive with FLL, FSP, FCI and FPY whereas, significant and negative with FDP. First lactation
milk yield and first peak yield had positive genetic correlation with lifetime traits. These results
suggested that selection based on FLMY and FPY individually or in combination would improve
lifetime production.