Heat Increments of Steam-Volatile Fatty Acids Infused Separately and in a Mixture into Fasting Cows

Abstract

Heat increments for equicaloric amounts of acetic, propionic, and butyric acids and a 52A:31P:17B molar mixture of acids were determined in mature, fasted dairy cows. Acids were infused continuously into the rumen at 32 kcal per kilogram body wt .75 daily. A number of rumen fluid and blood traits were measured daily during each of 10 experiments. No aci- dosis was indicated by the COs-combining capacity of whole venous blood. Mean heat increments were acetic acid, 40; pro- pionic acid, 18: butyric acid, 18; and acid mixture, 32 kcal per 100 kcaI metaboliza- ble energy.