Effect of Substitution of Cotton Seed Meal by Two Various Protein Sources on Productive Performance of Fattening Crossbred Calves

摘要

This study was carried out to evaluate the effect of three different protein sources on nutrienl digestibility, feeding value, growth performance and economic efficiency of growing calves diets. Twenty-tod growing crossbred calves (Balady x Friesian)aged 9 months and weighed in average 238.29 ± 26.25 wen randomly allocated into three similar groups (8 animals in each). Black cumin seed {Nigella sativa) meal (BCSMi and distiller's dried grains with solubles (DDGS) were incorporated into the experimental concentrate feel mixtures (CFM) to replace 100% of the cotton seed meal (CSM) as a source of protein (30% of total rationj The experimental feed mixtures were fed individually at 2% of calves' body weight in two parts daily at8a.ll and 4 p.m. Groundnut vine hay was offered at 1% of calves' body weight. The feeding trial lasted for 120 days, during this period animal's body weight were recorded biweekly and the feed intake was adjusted. AttU middle of the feeding trial (60 days), four animals from each group were randomly chosen and using a grab sample method to determine the nutrients digestibility and feeding value of experimental rations. Silica (acid insoluble ash, A1A) was used as internal marker for determine the digestibility. The results indicated also that the digestion coefficients of DM, OM, CP and NFE were significantly (p<0.05) higher (69.75, 73.63, 68.93 and 75.78% for BCSM ration than those of CSM ration (64.27, 67.85, 62.25 and 72.65%) and DDGS ration (63.35, 66.75, 63.53 and 73.23%), respectively. On the other hand, nutritive values expressed as TDN orDCP were significantly (p<0.05) higher for BCSM ration (72.76 and 10.61 %) than the values of CSM (66.53 and 9.34 %) and DDGS (70.27 and 9.66 %) rations. The results revealed that the total dry matter intake as concentrate i and roughage were not significantly different between all experimental rations. The results indicated that average daily gain for calves fed BCSM was 1209 g/d, followed by those fed DDGS and CSM which were 1096and 1087 g/d, respectively. Feed conversion as a kg DMl/kg gain was better for group 2 (7.71) than groups 1 (8.38) and 3 (8.32). Total feed cost/head and feed cost/kg gain were the lowest for BCSM ration (2569 and 17.7 L.E.) compared with DDGS (2647 and20.1 L.E.) and CSM (2683 and 20.6 L.E.) rations, respectively. On the other hand, the economic efficiency and economic feed efficiency of animals fed diet contained BCSM was higher (7.74 and 69.50%) than those fed diets contained CSM (2.51 and 45.60%) and DDGS (3.17 and 49.30%), respectively. The present study suggested the possibility of substitution of CSM by BCSM and DDGS in rations for growing or fattening calves. Black cumin seed meal ration had better nutrients digestibility, feeding values, daily gain and feed efficiency and economical efficiency compared with CSM and DDGS rations.