Relation of Dietary Acetate and Lactates to Dry Matter Intake and Volatile Fatty Acid Metabolism

Abstract

Effects of feeding lactates and acetate supplemental to a basal ration of two-thirds sorghum silage and one-third mixture of beet pulp and soybean oil meal were determined, using five heifers in a 5×5 Latin-square design. Rations were fed ad libitum. Lactates were added to give 9.0% lactic acid equivalent in the ration dry matter (HL) and acetate at 2.8% acetic acid equivalent (HA) significantly (P<.01) increased dry matter intake; at lower levels, 5.9% lactic (LL) and 1.5% acetic (LA), intake was not significantly different from the basal ration.Gains in body weight and efficiency of dry matter utilization were higher, but not significantly, when supplements were fed. The HA supplement increased the molar per cent of acetic acid; whereas, the HL supplement decreased the proportion of acetic acid and increased propionic acid. Blood levels of acetic, propionic, and butyric acids were highest for the HL treatment. Blood glucose and ketones were not apparently affected by these supplements.The results suggest that the depression in dry matter consumption and lower rates of gain which often result from feeding silage rations compared to hay are due to factor(s) other than the acetate and lactate contribution of silages.