Heteroskedasticity and genotype by environment interaction across European countries for weaning weight in Charolais breed

摘要

A preliminary analysis of heteroskedasticity and genotype by environment interaction was performed with purebred Charolais data originating from different European countries. A sample of 114 829 200-day weights, recorded between 1992 and 2000 and stratified into six different origins (Ireland, Italy and four French regions), was used. REML estimates were obtained under a sire, maternal grand-sire model. Results clearly showed the presence of heterogeneous variances across regions for both residual and sire effects, the major source of heteroskedasticity being the differences among countries. Estimated correlations (d) between sire effects in different regions suggested the absence of genotype/environment interaction throughout French regions (d=0.94) and even between France and Italy (d=0.81). Conversely, considerably lower correlation coefficients were obtained between Ireland and the continental regions.