It is important to understand the factors which limit forage intake in ruminants. Most work carried out on sheep has now been extended to the dairy cow. The effects and possible roles of the short chain fatty acids In the control of forage intake in the dairy cow, in particular, hay intake have already been reported (Mbanya, 1988). One of the factors in question is propionate which depresses intake when given intraportally in sheep, but hay intake in the dairy cow was not affected by intraruminal propionate. The aim of this study was to test the role of propionate in the control of silage intake which has economical importance in the dairy industry.

Five rumen fistulated Friesian cows in early lactation (mean yield 25 kg/day) were used in a Latin-square experiment and individually fed grass silage (DM: 229g/kg; CP: 158g/kg DM; MAD fibre = 349g/kg DM; ether extract: 42g/kg DM; ash: 96g/kg DM) ad libitum plus 6 kg of concentrate fed twice daily. 3h intraruminal infusions of the following were made on different days: Control (no infusion), 4,6 and 8 moles of sodium propionate in 41 water. Silage intake was measured during the 3h and for 2h post-infusion.