Abstract 271

Sudana,-IB; Leng,-RA

R.A. Leng, Dep. Biochemistry and Nutrition, Faculty of Rural Science, Univ. New England, Armidale, NSW 2351, Australia.

Animal-Feed-Scienceand-Technology. 1986, 16: 1/2, 25-35; 20 ref.

Lambs were given a basal diet of wheat straw plus 0.5% mineral mixture, supplemented with either 2.5% urea or 150 g daily of cottonseed meal (CSM) or 2.5% urea + 150 g daily of CSM or urea-molasses block (ad libitum) alone or with 150 g CSM. Supplementation of the basal diet with the urea-molasses block increased (P<0.001) straw DM intake by lambs from 333 to 420 g/day, and a liveweight loss of 53 g/day on the basal diet was improved to a liveweight gain of 10 g/day. Supplementation with CSM alone or CSM plus urea increased straw DM intake from 333 to 439 g/day and consequently converted a mean liveweight loss of 53 g/day on the basal diet to mean liveweight gains of 38 and 40 g/day. The combined supplement of CSM and urea-molasses block further increased straw DM intake to 475 g/day and lamb liveweight gain to 90 g/day. The supplementation of 2.5% urea alone did not affect either straw intake or liveweight gain. The use of the urea-molasses block as a urea supplement was superior to urea alone. The digestibility of straw as indicated by the loss of DM from straw in nylon bags in the rumen was increased by supplements of protein meals, but was highest when the urea-molasses block was also consumed. Wool growth was increased by 60% above that on the basal diet by supplementation with the protein or protein plus fermentable N sources.