Variance components and genetic parameter estimates using random regression models on test day milk yields of Holstein Friesians.

considered in genetic evaluation systems of dairy cows for a long time. Nowadays, the use of 305 day lactation records have replaced by consideration of test day records using test day models as repeatability, multivariate and random regression models which have been developed to model test day records directly . In repeatability model, test day records are considered as repeated observations of same trait but in multivariate model, test day records are considered Kafkas Univ Vet Fak Derg 15 (4): 547-551, 2009 RESEARCH ARTICLE