The production and absorption of volatile fatty acids from the rumen of the sheep

Abstract

Experiments are reported in which sheep were given roughage diets or a high concentrate diet and the VFA absorbed from the rumen were estimated by an in vitro fermentation procedure. The VFA absorbed were compared with the digestible and metabolizable energy intakes of the sheep, determined in digestibility trials, for each diet. For a lucerne diet, a straw diet, and the high concentrate diet the proportions of the digested energy absorbed as VFA were 33.6, 42.4, and 33.2% respectively. On the lucerne diet, the difference between the mean molar proportions of the VFA absorbed and the mean molar proportions of the VFA in the rumen approached significance for acetic acid (P < 0.10) and was highly significant for butyric acid (P < 0.01). The differences were not significant for the other diets.