Effect of Propionate and Citrate on Depressed Feed Intake After Intraruminal Infusions of Acetate in Dairy Cattle

Intraruminal infusions of acetic acid (neutralized to pH 6.5) reduced hay consumption in fistulated dairy heifers by 39%. Substitution of a portion of the acetate with an equicaloric amount of propionate prevented the depression. Addition of citrate to the acetate partially alleviated the depression. Temperature of the tympanum of the ear increased following infusion of acetate, but was maintained lower by the acetate-propionate mixture. The data suggest that a balance of the volatile fatty acids in the rumen may be a significant factor in controlling their voluntary feed intake.