The Effect of Urea Supplementation of High Grain Rations on the Metabolism of Fatty Acids in the Rumen of Sheep and Cattle

When rations containing, basically, sorghum grain were supplemented with urea, it was found that the urea affected the concentrations of certain fatty acids in the rumen and depot fat. On a ration of grain/sorghum silage similarly supplemented, isovaleric acid increased. There was a small affect of urea on the level of linoleic acid in the rumen of sheep which, however, was not significant at the 5 per cent level. When the levels of fatty acids in the omental fat of steers fed grain/sorghum silage plus urea were examined, it was found linoleic acid was significantly decreased. The influence of urea supplementation of high grain rations upon volatile fatty acid utilization and hydrogenation of unsaturated fatty acids is discussed.