Urea phosphate as a partial protein replacer in sheep concentrate diets

Abstract

SUMMARYIncubation with rumen liquor gave a lower rate of release of ammonia and a higher dehydrogenase activity with urea phosphate (UP) than with urea.Four concentrate diets containing 13 % crude protein, 27% of which was supplied by urea or three different forms of UP, were each given to eight Awassi lambs. With twice-daily feeding (but not five-times daily feeding), a beneficial effect of UP over urea was observed, expressed in lower blood ammonia and urea levels. There was no effect on the pH of rumen liquor.In a N-balance experiment with 24 lambs, four diets were examined: a basal diet containing 9·5% crude protein and three other diets in which the crude protein content was raised to 13% by addition of soya bean meal, urea or UP. The diets were given twice daily. Urea phosphate and the soya bean meal gave a significant increase in N retention whereas the urea treatment did not. However, the difference in N retention between the UP and urea treatments was not significant. Total volatile fatty acid concentrations in the rumen did not differ significantly between treatments but the ratio of acetic to propionic acids was significantly lower with the urea diet.