Genetic Evaluation of Crossbred Cattle for Reproduction Traits

The data on 333 crossbred cows maintained in the De partment of Animal Genetics and Breeding, Lala Lajp t Rai University of Veterinary and Animal Sciences, Hisar , Haryana over a period of 24 years from 1991 to 20 14 were analyzed for studying the effect of genetic factor i.e. sire gro up and non genetic factors i.e. period of calving, season of calving and milk yield group and to estimate genetic and phenotypic parame ters for reproduction traits. The traits studied we re age at first calving (AFC), first service period (FSP), first calving in terval (FCI), number of services per first concepti on (NS/FCON), waiting period (WP) and daughter pregnancy rate (DPR42, DPR 63). The least squares mean for AFC, FSP, FCI, NS/FCON, WP, DPR42 and DPR63 were observed as 1242.75±16.46 days, 1 48.46±6.99 days, 429.08±7.08 days, 1.90±0.12, 100.8 5±4.20 days, 0.27±0.02 and 0.35±0.04, respectively. The pe riod of calving had significant effect on AFC, whil e season of calving had significant effect on FSP and FCI. The milk yield g roup had significant effect on all traits. Heritabi lity estimates of these traits were low to moderate. Genetic and phenotypic correl ations among FSP, FCI, WP and NS/FCON were found to be moderate to high positive. DPR showed moderate and negative genetic correlation with FSP, FCI, WP and NS/FCON w hereas; corresponding phenotypic correlations with these tr ai s were significant negative.