The average daily gains of 6,420 Czech Pied bulls (dual-purpose, Simmental type) from 7 breeding stations wereanalyzed using single-trait animal models, a multi-trait animal model and random regression models. The effectsof station, year and season were taken into account by creating herd-year-season classes (HYS) with the seasonbeing defined as a 3-month class starting with December. Legendre polynomials of the 1st to the 4th degree wereused to describe the daily gains within the HYS classes as well as to model bull-specific gain curves. Thecomparison of the h-values estimated with single-trait models and those gained with a multi-trait model returnedonly insignificant differences. The comparison of genetic parameters based on the multi-trait model to thosefrom different random regression models shows that polynomials of at least the 2nd degree are to be used for thegenetic analysis of daily gains.
展开▼
