Genotype Environment Interaction between Organic and Conventional Dairy Production

Due to genotype by environment interaction (GxE), conventional bulls might not be suitable for organic production circumstances. Therefore, lactation records from Holstein cows on organic and conventional farms were used to estimate the magnitude of GxE between organic and conventional production circumstances. GxE was quantified by estimating the genetic correlations between production traits in both environments. Genetic correlations for milk and protein yield were between 0.71 and 0.80 and found to be significantly different from unity. For fat yield the correlations were close to 0.90 and not significantly different from unity. It can be concluded that breeding values for yield traits should be adapted to organic production so that the production level of cows fits better to the organic environment resulting in healthier dairy cows.