Genetic evaluation for milk production, reproduction and somatic cell count traits in early lactation for friesian cattle in Egypt

A total of 2396 records of 673 Holstein Friesian cows were collected from one commercial Holstein Friesian farm during the period from 1999 to 2004. Genetic, phenotypic correlations and breeding values for productive, reproductive and somatic cell count traits were analyzed by using single-trait and multi-trait animal model analyses. Traits studied were total milk yield (TMY, kg), days in milking (DIM, days), milk yield in first test of lactation after calving (M1, kg), days open (DO, days), number services per conception (NSC, services), age at first calving (AFC, month), and somatic cell count in the first test of lactation (SCC). Unadjusted means of TMY, M1, DIM, SCC1, AFC, NSC and DO were 6716 kg, 17.39 kg, 319.8 day, 505.23x103 cell/ml, 28.3 month, 1.97 services and 144.5 day, respectively. Estimates of heritability of TMY, DIM, M1, SCC1, AFC, NSC and DO were 0.34±0.028, 0.22±0.08, 0.10 ± 0.026, 0.04±0.023, 0.20±0.113, 0.02±0.013 and 0.02±0.017 for single-trait, While, the obtained h. from multi-trait analysis were 0.40±0.12, 0.20±0.16, 0.16±0.02 and 0.10±0.08 for TMY, M1, DO and SCC1, respectively. The genetic correlations among TMY, M1, SCC1 and DO were positive and ranged from 0.19±0.06 to 0.84±0.08. The phenotypic correlations between milk production and reproduction traits were positive for all studied traits and ranged between 0.10 for correlation between SCC1 and TMY to 0.44 for correlation between M1 and DO. The range of breeding values obtained from single-trait analysis for DO, TMY, M1, SCC1 and AFC were 20.9 day, 6006 kg, 229 kg, 57.7 x 10. cell/ml and 3.83 month, respectively. While, the breeding values obtained from multi-trait analysis for all animals were 193.9 day, 10280 kg, 383.8, and 630x10. cells/ml for DO, TMY, M1, and SCC1, respectively. The present results will help the farmers to select the best dairy cows based on a combination of production, reproduction and somatic cell count in early lactation