Genetic Evaluation for Some Productive and Reproductive Traits by Using Animal Model in A Commercial Friesian Herd in Egypt

Abstract

Data used in this investigation were collected from 4370 records for 874 purebred Friesian cows' daughters of 44 sires from 1985 to 2003, which belong to Shobratana Animal Production Society, located in the north part of Delta region near Tanta city in Egypt. Variance and covariance components for 305 day milk yield (305- dMY, kg), lactation length (LL, day), dry period (DP, day), days open (DO, day) and calving interval, (CI, day) were estimated with REML using an animal model (Boldman, 1955), that included the fixed effects of month and year of calving and parity of cow. Random effects were animal, direct and maternal genetic effects, maternal permanent environmental effect and random effect.Overall means of (305-dMY), LL, DP, DO and CI were 4897 kg, 327 day, 120 day, 66.3 day and 401.16 day. Month and year of calving were highly significant effect (P<0.01) for all studied traits. Direct heritability (h2a) of the mentioned traits was 0.38, 0.13, 0.14, 0.11 and 0.16, respectively. Heritabilities of maternal effects (h2m) of (305-dMY) (0.13), LL (0.18), DP (0.23), DO (0.14) and CI (0.21), respectively. Estimates of direct-maternal genetic correlations in all traits studied ranging from -0.60 to 0.74. Genetic correlations among different studied traits ranged from -0.80 to 1.00 while the phenotypic correlations among investigated traits were positive, ranging from 0.07 to 0.99.Range of predicted breeding value (PBV's) of sires were 462 kg, 1.05 d, 0.24 d, 5.93 d and 2.26 d, for 305dMY, LL, DP, DO and CI, respectively. PBV's of cows of the mentioned traits was 1123 kg, 2.92 d, 1.64 d, 5.93 d and 2.92 d respectively. Corresponding PBV's of dams for the above same traits were 510 kg, 1.42 d, 0.80 d, 7.20 d and 3.00 d, respectively. Accuracy of (PBV's) ranged from 38 to 88, 73 to 88 and 39 to 89% for sires, cows and dams, respectively; indicating the genetic improvement could be attained through any bath of them. Estimates of temporary environmental variance as a proportion of phenotypic variance for LL, DP, DO and CI ranged from 35 to 71% indicating the improvement in these traits could be achieved by improving for these temporary factors.