Dhaka, S.S.Kapil Dev2018-10-292018-10-292018http://krishikosh.egranth.ac.in/handle/1/5810082463The present study was conducted on 862 crossbred cows maintained at Cattle Breeding Farm, Department of Animal Genetics and Breeding, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, Haryana over a period of 20 years from 1997 to 2016. In addition to this, a total of 40 animals were also screened for the presence of polymorphism in genomic region of CACNA2D1 genes with an objective to find the association of different genotypes with the production traits. The overall least -squares means for lactation milk yield (LMY), lactation milk yield-305 (LMY-305), lactation length (LL), peak yield (PY), average daily milk yield (AMY), milk yield per day of calving interval (MCI), milk yield per day of age at second calving (MSC) persistency, age at first calving (AFC), service period (S.P), calving interval (CI) and dry period (DP) were 3111.81± 110.17 kg, 2929.45±90.63 kg, 310.57±6.48 days, 14.65±0.48 kg/day, 9.92±0.24 kg/day, 7.80±0.23 kg/day, 1.93±0.07 kg/day, 208.94±5.86 days, 1235.22±19.53 days, 113.85±4.55 days, 401.65±5.53 days and 87.19±4.08 days, respectively. The overall least-squares means for different test day milk records were 8.11±0.24 kg/day, 11.65±0.28 kg/day, 13.95±0.28 kg/day, 12.51±0.25 kg/day, 11.39±0.21 kg/day, 10.23±0.18 kg/day, 9.10±0.17 kg/day, 8.32±0.16 kg/day, 7.34±0.13 kg/day and 6.33±0.11 kg/day for TD1 to TD10, respectively. With regard to production performance traits, the effect of period of calving was statistically significant on all the production performance traits except on AFC, SP, CI and DP. While, the effect of season of calving was non-significant on all the production performance traits except significant effect on AFC, SP, CI and DP. The effect of parity was statistically significant on all the traits except on LL, PY, SP and CI. The heritability estimates for various production performance traits were found to be low to high ranging from 0.04±0.01 (SP) to 0.50±0.12 (MSC) and for test day milk records it ranged from 0.32±0.17 (TD8) to 0.47± 0.16 (TD4). The positive and high genetic association among production performance and with test day milk records indicated that test day milk records could successfully be utilized for genetic evaluation of sires for FLMY. The average EBVs for production traits viz. LMY, LMY-305, LL, PY, AMY, MCI, MSC, Persistency, AFC, SP, CI and DP were obtained as 2408.57 kg, 2257.0 kg, 297.92 days, 14.58 kg/day, 7.93 kg/day, 5.96 kg/day, 1.48 kg/day, 162.87 days, 1243.17 days, 120.09 days, 404.82 days and 101.74 days, respectively. The average EBVs for test day milk records viz. TD1 to TD10 were obtained as 8.17 kg/day, 11.61 kg/day, 13.92 kg/day, 12.52 kg/day, 11.22 kg/day, 9.90 kg/day, 8.58 kg/day, 7.22 kg/day, 6.16 kg/day and 4.42 kg/day, respectively. Spearman‟s rank and product-moment correlations between EBVs of FLMY, MSC, AFC and FCI from multivariate animal model in combination with TD3 showed that multivariate animal model combinations viz. FLMY-MSC-AFC-TD3, FLMY-FCI-AFC-TD3 and FLMY-MSC-FCI-TD3 had positive, high and significant rank and product-moment correlations between EBVs for various models. The error variance was found the lowest for FLMY-FCI-AFC-TD3 combination. Hence, multivariate animal model having FLMY-FCI-AFC-TD3 combination is recommended for estimation of breeding value of first lactation milk yield as this combination not only take care of milk yield but fertility of animals also. Spearman‟s rank and product-moment correlations between EBVs of FLMY, MSC, AFC and FCI from multivariate animal model in combination with TD3 showed that multivariate animal model combinations viz. FLMY-MSC-AFC-TD3, FLMY-FCI-AFC-TD3 and FLMY-MSC-FCI-TD3 had positive, high and significant rank and product-moment correlations between EBVs for various models. The genotypic and allelic frequencies were obtained as GG = 62.5, AA = 5, AG = 32.5 with allelic frequencies of G = 0.79 and A = 0.21 at A38795904G locus meet the Hardy–Weinberg equilibrium (p<0.01). The association between different genotypes of A38795904G SNP of CACNA2D1 gene and production performance traits revealed significant association (p<0.01) with LMY-305 and FLL with the highest value of association of AG genotype with LMY-305 (2986.46±156.10 kg). While, it was the highest for AA genotype with FLL (432.00±31.09 days). So, differential association with two antagonistically associated traits i.e., mastitis incidence and milk production traits can be utilized for simultaneous genetic improvement of the animals once validated on a large sample of animals.enThesis