Sire by environment interaction in sheep may re-rank sires for some traits

Abstract

Through analysis of field data from Sheep Genetics Australia, we estimated genetic correlations among breeding values in different environments, classified into quintiles by contemporary group averages for body weight (BWT), clean fleece weight (CFW) or weight of wool impurities (WIMP). A genetic correlation was considered to be low enough to be of concern if its upper 95% confidence limit was below 0.80, indicating a statistically significant genotype by environmental interaction (GxE). There appear to be significant GxE for body weight, eye muscle and fat depth in yearlings in all three environment classifiers and for hoggets classified on WIMP. The wool weights and to some extent also wool impurities also showed significant GxE in both yearling and hogget data. For the most part, wool quality traits were free of significant GxE interactions.