College of Veterinary and Animal Sciences, CSK, HP Krishi Vishvavidyalaya, Palampur-176062, India.
1 Corresponding author.
2 Retired from Department of Animal Genetics and Breeding, College of Veterinary Sciences and Animal Husbandry, Mathura - 281 002, (U.P.).
First lactation milk production records on 1172 Jersey cows maintained from 1974 to 1995 at 4 institutional cattle breeding farms in sub-temperate mid-hill region of Himachal Pradesh were analyzed to study to effect of various non-genetic factors viz. farm, year and season of calving on part and complete first lactation milk production traits. The traits included part lactation milk yield upto 90, 150 and 305 days, first lactation milk yield, lactation length (LL) and dry period (DP). The sire-effect was highly significant for all the traits under study. All the non-genetic effects considered in the study, significantly affected the milk production traits along with significant linear regression of traits on age at first calving. The LL and DP were Significantly influenced by the farm effect only. The quadratic regressions of all the traits studied on age at first calving were observed to be nonsignificant in the present study except DP which was highly significant.
