Estimation of genetic parameters for somatic cell count in the first three lactations using random regression

摘要: Abstract Genetic parameters were estimated for loge somatic cell count (LSCC) the first three lactations of 31 236 Holstein/Friesian cows with 308 534, 236 277 and 206 729 test day yields in parities 1, 2 3, respectively. An animal random regression model was employed analyses using Gibbs sampling each parity regarded as different traits. Linear quadratic functions fitted permanent environmental effects respectively, orthogonal polynomials. Daily heritabilities increased days milk (DIM) averaged about 0.07 all parities. This increase DIM due to an genetic variance decreases both residual variances DIM. Environmental have a large influence on LSCC early lactation Within lactation, correlations highest between adjacent but decreased got further apart. However, this decrease slowest one greatest three. The lowest correlation within 0.10 7 305 3. Across lactations, intermediate 1 2. computed completed 0.69, 0.79 0.98 2, Corresponding phenotypic 0.38, 0.31 0.52, A model, accounting these variations correlations, should result more accurate evaluation.