The effect of the frequency of ingestion of urea on voluntary feed intake, organic matter digestibility and nitrogen balance of sheep

Abstract

The effect of the frequency of ingestion of urea by wethers on the voluntary feed intake, organic matter digestibility, and nitrogen balance was determined. Two rations, one a pelleted mixture of sorghum stubble, sorghum grain, molasses, volatile fatty acids, and minerals (1.23 per cent N) and the other a cereal straw (0.44 per cent N) plus minerals, were used. All sheep, except a control group, received a total of 6 g of urea per day, as a drench, either in one dose of 6 g, two of 3 g, three of 2 g or two 6 g doses three hours apart on every second day. All sheep dosed with urea ate more feed than the control group. The increase was greater for those that received the straw than for those that received the pelleted ration. Feed intake increased with increasing frequency of urea administration. Urea also increased the organic matter digestibility of the cereal straw, and the nitrogen balance of sheep given this ration but did not affect digestibility or nitrogen balance in sheep fed the pelleted ration. Sheep fed cereal straw supplemented with urea lost significantly less weight than the unsupplemented sheep.