Estimating effects of permanent environment, lactation stage, age, and pregnancy on test-day yield.

摘要: Test-day variances for permanent environmental effects within and across parities were estimated along with lactation stage, age, pregnancy use a test-day model. Data records calvings since 1990 Jerseys Holsteins from California, Pennsylvania, Texas, Wisconsin. Single-trait repeatability models fitted milk, fat, protein yields. Method R preconditioned conjugate gradient equation solver used variance component estimation because of large data sets. yields adjusted calving season, milking frequency breeding value (EBV) expressed on daily basis. To assess the effect adjustments, also analyzed without adjustment. For data, relative to phenotypic ranged 8.3 15.2% 4.4 8.3% 6.9 11.0% regions breeds; parity 31.4 34.7% 18.2 22.3% 28.3 29.1% similar breeds. Adjustment EBV reduced removed cow genetic variance. Relative unadjusted testday nearly identical those yields, heritabilities 0.19 0.30 0.13 0.15 0.17 0.23 protein. Adjustments age at milking, previous days open, pregnant using same single-trait ratios environment