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The objective of this study was to evaluate the effect of wet enriching a number of total mixed ration based on wheat straw (WS) with urea, on nutritional value, digestibility and feed consumption. For this purpose, in the first stage of the experiment, 5 rations containing: 1) 95.3% of WS, 2) 93.3% of WS, 16.0% of barley grain, and 16.0% of wheat bran, 3) 47.7% of WS, 23.8% barley grain, and 23.8% wheat bran, 4) 47.7% WS, 19.7% barley grain, 19.7% wheat bran, and 8.2% soybean meal, and 5) 47.3% WS, 16.0% barley grain, 16.0% wheat bran, and 16% alfalfa hay were prepared and then were add 4.0% urea, 0.3% salt, 0.2% sulfur and 0.2% vitamin-mineral supplement to all diets. Each of the experimental diets were completely mixed with whey with an equal weight ratio, and then were sampled of diets. Mixed rations were ensiled for 60 days and resampling was done after opening. Chemical composition, nutritional value, fermentability parameters and microbial protein synthesized were measured and compared measured in the samples of each diet before and after ensiling. In the second stage of the experiment, the effect of wet enriching diets 2 and 4 with urea were examined in unfermented and fermented form an in vivo study. Five Zell lambs placed in metabolic cages were used in during four 20-day periods (including; 15-days adaptation and 5-days sampling) to evaluate, dry matter intake, nutrient digestibility and rumen fermentability in response to feeding experimental diets. All variables were statistically analyzed using the GLM procedure of the SAS program in a completely randomized design. The means were compared using Duncan's multiple-range test procedure with an error level of 5%. The results showed that in all experimental rations the appearance characteristics of the silage in texture strength, pleasant smell, natural color and mold were acceptable, and seeping, moldiness or destruction no were observed. In all experimental diets, the concentration of crude protein and starch decreased after ensiling, and the largest decrease was in the diet containing only WS (diet 1). The starch concentration in all of total mixed rations ensiled were affected by Enrichment with urea and were decreased. It was concluded that, wet processing and deposition of wheat straw with urea and in a TMR form, can be a suitable method to improve the nutritional value and digestibility of WS alone,or in a ration with wheat bran and barley up to 23.8 percent. but by decreasing of whet straw and increasing concentrate in TMR rations, this method did not improve of ADL, and finally breaking of lignocellulose band.Finally,addeding wheat straw and barley improve the quality of wet TMR either an absorbents or supplement feed part.
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