Heat Increments of Feeding in Ruminants

Abstract

IN ruminants the heat losses associated with carbohydrate dissimilation amount to 30–70 k.cal./100 k.cal. carbohydrate digested¹, whereas in man such losses are only 5–7 k.cal./100 k.cal.². In calorimetric experiments with fasted sheep, we have found that the steam-volatile fatty acids which are the major end-products of rumen fermentation of carbohydrate produce a greater heat increment than does glucose given under similar conditions, precautions having been taken to minimize bacterial fermentation of the sugar. Furthermore, in starved animals, and also in those receiving food, the energy-loss as heat is considerably greater for acetic acid than for propionic or butyric acids.