Good quality maize silage with a high starch content and DM digestibility when fed to dairy cows increased forage intake, milk production and milk protein concentration compared with grass silage or low starch maize silage (Fitzgerald, 1997). Due to the low crude protein (CP) content of maize silage compared with grass silage, additional protein supplementation is required in the concentrate. The optimum level of protein in the concentrate for maize silage based forages differing in starch content was investigated in this study.
Three forages consisting of either all grass silage (GS) or mixed forages of grass silage and maize silage (40:60 DM mix) which contained either a low (LSM) or a high (HSM) starch content were offered ad libitum to individually fed dairy cows in early lactation (12 cows/forage). Each forage was supplemented with concentrates (6 kg/day) containing 180, 230 or 280 g CP/kg according to a change over design (3 periods of 3 weeks/period).