Effect of Feeding Dietary Treated Wheat Straw with Urea and Whey on Fattening Lambs Performance

This study was conducted to evaluate the effect of feeding treated wheat straw with urea and whey on fattening lambs performance. about 4.5 kg urea and 1.5 kg salt were dissolved in 40 l water and mixed with 30 l of whey. the solution was spread over 100 kg chopped wheat straw. thirty two male lambs were randomly divided into four feeding groups to compare performance with diets based on barley supplemented with 30% wheat straw. treatments were (1) 30% untreated wheat straw (uws) (control), (2) 20% uws + 10% treated wheat straw (tws), (3) 10% uws + 20% tws, (4) 30% tws. lambs were fed with isocaloric and isonitrogenous grower diets. the animals were slaughtered after 85 days of feeding and carcass parameters were measured. average final weights did not differ significantly between groups (p>0.05). however, average live daily and weight gain were significantly (p<0.03 and p<0.001, respectively) higher in lambs fed treatment 3. feed conversion ratio was lowest in lambs fed 20% and 10% tws followed by those fed control diet, which in turn were superior to those fed 30% tws diet (p<0.03). the highest values for average live weight gain and live daily gain were observed for animals fed 20% tws diet and the differences were only significantly higher than 30% tws diet. however, carcass weights were similar for the diets (p>0.05). dissection of different anatomical parts showed a higher percentage of lean meat, carcass fat and internal fat in animals fed tws compared to control but the differences were not significant. the lambs showed similar growth rates like control group, however, feeding cost per kg of body weight gain was lower in the experimental diet. carcass and meat quality were not affected by treatments. thus, the diet con-taining tws could not represent an economic advantage for procedures. the results indicate that tws silage can replace as part of uws. in conclusion supplementation of tws with a barley based concentrate support did not have positive effect on fattening lambs performance before and after slaughtering.