Genotype x environment interactions for digestibility traits in silage maize estimated from in vivo measurements with standard sheep

The aim of this work was to investigate the genotype x environment interaction for in vivo digestibility of organic matter and of crude fibre in silage maize evaluated with standard sheep experiments. In order to test the genotype x year interaction, the first experiment consisted of taking data subsets out of a 26-year experiment and evaluating in vivo digestibility traits at Lusignan (France) on numerous maize genotypes. In order to test the genotype x location interaction, the second experiment was a specific one whereby five hybrids were cropped in diverse locations and then evaluated from experiments with sheep, at Lusignan. The variation attributed to genotype x environment (either a year or a location) interaction for in vivo digestibility traits was distinctly lower than the variation due to the main genotypic effect. Therefore, the in vivo digestibility of organic matter and of crude fibre in maize genotypes could be accurately assessed from silages cropped in a simple experimental design, which included replicates, but only a small number of years or locations. This also confirmed the results obtained with in vitro digestibility traits from large multi-environmental designs which highlighted the low importance of genotype x environment interactions and contributed to the validation of in vitro criteria.