Effect of Urea-Treated and Untreated Wheat Straw with or Without Fibrolytic Enzyme Addition on Nutrient Digestibility and Rumen Fermentation of Awassi Lambs

A digestibility trail was conducted on 16 Awassi lambs at the ruminant farm belonging to the Faculty of Agriculture, University of Kufa, Najaf, Iraq, to study the effect of untreated and urea-treated wheat straw with or without fibrolytic enzyme (Safaziyme®, enzymes cocktail contained: β-glucanase, xylanase and cellulase) supplementation on the nutrient digestibility and rumen fermentation of Awassi lambs. Animals were distributed randomly into four groups (4 lambs each) and the groups included: T1: Concentrated diet + untreated wheat straw (control); T2: Concentrate diet + wheat straw treated with 3% urea solution; T3: Concentrated diet supplemented with fibrolytic enzymes (2g/lamb/day) + untreated wheat straw; T4: Concentrated diet supplemented with fibrolytic enzymes (2g/lamb/day) + wheat straw treated with 3% urea solution. Lambs individually fed concentrate diet at 3% of live body weight while wheat straw treated with urea or untreated was offered ad libitum . Results revealed that dry matter digestibility and other nutrient digestibility were not affected significantly by experimental diets except crude fiber digestibility, it was superior ( P ≤ 0.05 ) when lambs fed urea treated wheat straw +fibrolytic enzymes supplementation (T4) followed by lambs fed urea treated straw (T2) as compared with lambs fed control (T1). Results revealed that ruminal pH and concentration of ammonia nitrogen (NH 3 -N) were not significantly affected by experimental diets. Total volatile fatty acids concentration was significantly higher ( P ≤ 0.05 ) in lambs of the T4 group followed by the T2 group. In conclusion, the combination of urea treated wheat straw + supplemented with fibrolytic enzymes enhance nutrient digestibility and rumen fermentation in Awassi male lambs.