Responses in milk yield from feeding grain and meat-and-bone meal to cows grazing tropical pastures

An experiment was conducted with 36 Holstein-Friesian cows to determine the effect on milk yield and milk composition of feeding maize grain with or without meat-and-bone meal (MBM) at high levels of pasture on offer. Cows were offered ground maize with and without MBM to give supplements of 3.0, 5.5 and 8.0 kg DM/day at 16% or 10% crude protein. Animals grazed nitrogen-fertilised tropical grass and grass-legume pastures. Milk production was recorded over a 300-day lactation. Milk yields over 300 days at 3.0, 5.5 and 8.0 kg DM/day averaged 5435, 5605 and 5882 kg/cow, respectively. For milk yields over both 100 and 300 days, a linear response to grain supplement occurred. This represented 0.22 kg milk/kg DM (P<0.05) for the first 100 days, and 0.30 kg milk/kg DM (P=0.087) over the 300-day lactation. Cows receiving MBM tended to lose less (P=0.068) liveweight in the period 1-100 days and to gain more (P=0.054) between 100 and 300 days than cows without MBM. Milk yields across treatments for cows fed with and without MBM averaged 2143 and 2061 kg/cow (P>0.05) for days 1-100, and 5668 and 5614 kg/cow (P>0.05) for days 1-300 of lactation.