Genotype by environment interaction for Merino sheep in New Zealand and Australia for a range of traits

In this study, we examined the significance of genotype by environment interactions for Merino type animals under Australian and New Zealand production systems, for a range of traits, with data sourced from the MERINOSELECT database. Bivariate analysis of traits between Australia and New Zealand with the genetic correlations giving an estimate of genotype by environment interaction. Models with and without sire by flock-year effects was examined to address practical problems associated with Industry data. The variance components and heritabilities were generally similar between both countries and between models including and excluding sire by flock-year effect. Genetic correlations were generally high between countries when sire by flockyear effect was fitted with only three of the traits having correlations < 0.8. These traits were yearling clean fleece weight (0.56 ± 0.22), yearling greasy fleece weight (0.74 ± 0.12) and yearling fibre diameter (0.73 ± 0.09), however, only ycfw was actually < 0.8 based on standard errors. By accounting for the sire by flock-year effect, genetic correlations for traits between Australia and New Zealand increased. With the high level of genetic correlation between countries, ram breeders can use MERINOSELECT ASBVs to select animals regardless of the country in which those animals were born.