Maize silage for dairy cows : effect of grain content on performances

Abstract

The effects of a lower grain content in maize silage hybrids (resulting from discarding a part of the ears on harvest time) on DM intake, body weight variations, yield and composition of milk by highyielding dairy cows were investigated. Cows were individually fed ad libitum with the experimental or the control roughage diets. They received concentrates according to requirements (3 trials) or under energetic requirements (1 trial). The experimental periods lasted for 10 to 14 weeks. Neither roughage DM intake (15.9 kg/cow/day for the experimental diet versus 16.0 kg for the control) nor body weight gain (20 kg/cow/period versus 26 kg) or milk yield (22.9 kg/cow/day versus 22.8 kg) were modified by the lowering of the grain level from 50 % (total DM basis) to 44 %. Milk fat concentration and protein content were only affected by the experimental diet during the last trial. The apparent digestibility of the non-grain part of the silage, estimated by cows performances, seemed to be higher when the grain content is lower (1.21 Mcal/DM kg versus 1.12 Mcal). None of the digestibility predicting tests used in this study was pertinent for the prediction of the energetic value, according to cows performances. Maize hybrids with a higher total DM yield but with a lower grain content (5 to 10 points) than the modern hybrids could be fit for dairy cows feeding.