Performance of Growing Lambs Fed Urea Ammoniated and Urea Supplemented Wheat Straw Based Diets

Twelve growing male lambs ($10.05{\pm}0.41kg$, 5 months age) were assigned to three equal groups in a completely randomized design and fed respectively wheat straw (WS), ammoniated wheat straw (AWS) or urea supplemented wheat straw (USWS) along with concentrate mixtures of varying protein and energy contents to meet their requirements as per NRC (1985). Despite comparable nutrient intake and digestibility, the lambs fed A WS based diet digested lower (p<0.05) crude protein. The digestibility of NDF and hemicellulose were lower while the digestibility of cellulose was higher in lambs on AWS as compared to lambs on USWS based diet. The lambs of all the three groups were in positive and comparable N, Ca and P balance except higher Ca balance in lambs fed WS based diet. The body weight change, average daily gain and feed conversion efficiency were similar among the dietary groups. All the parameters of rumen fermentation pattern were comparable between lambs of AWS and USWS based diets except ammonia-N concentration that was higher in the latter however it was lower in WS fed group. Though, the feeding cost per unit gain was comparable in lambs fed all the three diets, the cost incurred towards roughage during 120 days of experimental feeding was significantly less in lambs fed AWS than UTWS. Thus, feeding of USWS can be practiced to minimize labour cost and environmental pollution involved in the process of urea treatment without affecting the performance of growing lambs.