Effect of feeding different levels of fatty acids or calcium soaps of fatty acids on digestion and metabolizable energy in sheep

Abstract

ABSTRACTSheep were given diets containing 0, 30, 50 or 90 g/kg added free fatty acids from palm oil or from calcium soaps prepared from the same fatty acids in a three period switch-over design. Addition of free fatty acids to the diet enhanced metabolizable energy (ME) intake when added at 30 and 50 g/kg but not at 90 g/kg. On feeding 90 g/kg free fatty acids, rumen volatile fatty acid levels decreased and acid-detergent fibre and protein digestion was reduced. Calcium soaps of fatty acids enhanced ME intake at all levels added and had no effect on rumen fermentation. Addition of both free fatty acids and calcium soaps of fatty acids enhanced apparent digestibility of total fatty acids and of all fatty acids except stearic acid. The ME of free fatty acids added at 30 g/kg was 35·56 MJ/g and of calcium soaps of palm oil was approximately 33·05 MJ/g.