GENETIC ANALYSES OF CALVING TRAITS IN THE SWISS BLACK AND WHITE, BRAUNVIEH AND SIMMENTAL BREEDS BY REML AND MAPP PROCEDURES

Fixed effects, genetic and phenotypic parameters were estimated for birth weight, gestation length, dystocia and stillbirth using a multitrait REML (Restricted Maximum Likelihood) procedure on a model that included effects of herd × year, season, sex of calf, parity of cow, genetic group of sire of calf and sire of calf. Observations on the calves of test sires from the three Swiss cattle breeds Black and White (BW), Braunvieh (BR) and Simmental (SI) were used. Sex of calf and parity of cow (first vs. later) had the largest influence on all traits analysed and in all breeds. Genetic groups of sires, according to percentage of U.S. Brown Swiss genes in BR and Red Holstein genes in SI had also a moderate to large effect on these traits. Considerably smaller heritabilities for dystocia and for stillbirth were found in BR than in the other two breeds. Some breed differences were observed in the genetic correlations. It was found that a model containing a random herd classification with a ratio of error to herd variance between 5 and 20 yielded useful heritability estimates for dystocia with a MAPP (Maximum A-Posteriori Prediction) or a REML procedure. Correlations of 0.97 and 0.99 were observed between breeding values estimated by a linear or a nonlinear procedure for dystocia and for stillbirth. For both traits slightly higher correlations between the two breeding values of the same sire, after randomly splitting the daughters into two groups, were found within the linear than within the nonlinear procedure. © 1990.