The place of maize and of pastures in dairy forage systems. I. Maize silage in the feeding system.

摘要

Maize silage, as the sole constituent in the diet of dairy cows, was compared with various winter diets (grass silage, maize silage + grass or legume silage, maize silage + beets) in 35 trials, and was also tested as a supplement to grazing in 16 trials. The voluntary intake of grass silage was lower than that of maize silage (-2 kg DM) but the milk yield was the same and the milk was less rich (-2.8 g/kg protein). The intake of a mixed diet with 2/3 maize and 1/3 grass silage was the same as thatof pure maize, and the milk yield and quality remained unchanged. The effect of adding legume silage to the diet was negative: there was a decrease in milk fat (-1.8 and -0.4 g/kg respectively for red clover [Trifolium pratense] and for lucerne [Medicagosativa]) and in milk protein contents (-1.0 and -0.9 g/kg). When given as a complement to grazing, maize increased the milk fat content (+1.2 g/kg), but decreased the voluntary intake of grass, particularly in summer and autumn, which may then not exceed 3 kg DM/cow per day. The first results of a comparison between 2 forage systems with a large or a small proportion of maize silage (88% vs 20%) showed an advantage of only 400 kg milk in favour of the diet with a large proportion of maize.