The Veterinary Record, Vol 139, Issue 7, 162-165
Copyright © 1996 by British Veterinary Association

Effect of forage supplements on the incidence of bloat in dairy cows grazing high clover pastures

¹ Department of Clinical Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES
² School of Agricultural and Forest Sciences, University of Wales, Bangor, Gwynedd LL57 2UW

The effect of offering forage supplements of different compositions was examined in two experiments with cows grazing high clover swards. In the first experiment strawmix supplements of high or low energy content (11 and 9 MJ metabolisable energy/kg dry matter [DM]) and high or low crude protein content (17 and 4 g/kg DM) were offered for periods of three weeks. The energy and protein contents were varied by the content of molasses and soyabean meal, respectively. The high energy, high protein supplement increased the incidence of bloat, and the low energy, high protein supplement reduced it, compared with grazing alone. Bloat was most evident in the first two weeks of each feeding period, suggesting that the cows partially adapted to the diets within three weeks. In the second experiment silage supplements reduced the incidence of bloat among cows grazing both tall and short swards. The most suitable forages to feed when there is a risk of bloat are those that are slowly fermented in the rumen but are eaten in sufficient quantity to reduce periods of rapid herbage intake.