Abstract

This study evaluated the effect of wheat straw urea treatment and Leucaena leucocephala (LL) foliage hay supplementation on intake, digestibility, nitrogen balance and growth of Ethiopian highland sheep. Thirty-six yearling male lambs were randomly allotted, in randomized complete design, to six dietary treatments:- untreated wheat straw (T1); urea treated wheat straw (T2); T2 plus 100, 200, 300 g LL in T3, T4, T5 respectively, and T1 plus 300 g LL per lamb/day (T6). The lambs were fed for three months. Urea treatment increased straw crude protein (CP) content (g kg^-1DM) (32 vs. 60) and decreased neutral detergent fiber (NDF) (807 vs. 743), acid detergent fiber (ADF) (523 vs. 504) and acid detergent lignin (ADL) (75 vs. 70). Straw intake was increased (P<0.001) with urea treatment and supplementation. Total DM intake (g/day) peaked (P<0.001) in T5 (750) compared to T6 (546.9). Lambs in T2 gained 10.7, while lambs in T1 lost 33.9 g/day. The highest average daily gain (47.2 g) was achieved in T5. Digestibility of DM, organic matter (OM) and CP was higher (P<0.001) in T2 than T1. Supplementation increased the digestibility of DM, CP and Ash significantly. Digestibility of nutrients, except CP, was higher (P<0.001) in T5 than T6. Nitrogen balances (g/day) were positive, except in T1 (-0.71 g/day) and increased (P<0.001) with supplementation. Total nitrogen excretion (g/day) was higher (P<0.001) in T2 (4.64) than T1 (2.97) and increased with supplementation. It is concluded that combined use of urea treatment and LL supplementation improves feed utilization and lambs' performance better than using them separately.

Key words: Wheat straw, urea treatment, leucaena, intake, live weight, lambs.