FLOW AND NUTRIENT DIGESTION IN YEARLINGS FED UREA RICH DIETS

An experiment was carried out with 4 Holstein ''yearlings, fitted with cannulae in the duodenum and ileum, to determine the now to the duode num and the ruminal and intestinal nutrient digestion in urea rich die ts. Treatments were: (a) urea diet, 79.8% steam flaked maize, 15.7% su dan grass and 1.6% urea; and (b) typical diet, 70% steam flaked maize, 15.7% sudan grass and 11.4% cottonseed meal. Both diets contained 12. 4% CP, the urea diet contained 4.6 per cent units of CP in the form of NPN. The microbial N (P < 0.05) flow to the duodenum and ADF (P < 0.1 0) were higher in the urea diet. Intestinal and rumen-intestinal diges tibility of the DM, OM, N and starch was not affected by the N source in the diet. These results suggest a similar amino acid availability b etween escape and microbial proteins. Data also indicate that the nutr ient flow to the duodenum, in both diets could support comparable grow th rates, although liveweight gain could be improved with the inclusio n of amino acid sources that are more available at the intestine, in d iets rich in urea.