Macro- and micro-genetic environmental sensitivity for 400-day weight in Australian Angus

Genotype by environment interactions can be caused by both macro- and micro-genetic environmental sensitivity (GES ). In the current study, 400 day weight (400DW) measured on Australian Angus was analysed using a variability model and a reaction norm model to obtain estimates for genetic variation due to macro- and micro-GES. The results showed additive genetic variance for both macro- and micro-GES. Over the range of contemporary group means the macro-GES impacted the genetic variance and ranking of sires across environments. The presence of micro-GES indicated the possibility of selecting to reduce the variability of phenotypes, but further investigation into the consequences is needed.