Eighty growing buffalo calves, 14-16 months old, with an average weight of 202 kg, were divided, randomly, into four equal experimental groups, (20 calves each), and used to investigate the effect of replacing 0%, 10%, 20% and 30% of soybean and yellow corn by dried distiller's grains with soluble (DDGS) in total mixed rations (TMR) (1,2,3 and 4, respectively). The experimental diets were nearly similar in crude protein (CP) (iso-nitrogenous) and total digestible nutrients (TDN) (iso-caloric). All animals were fed daily 3% of live body weight and the trial lasted for 180 days. Metabolism trials were carried out on three mature rams for each TMR to estimate nutrient digestibilities, nutritive values and nitrogen balance. The economic efficiency was also calculated. Significantly lower values of live body weight and daily gain were recorded for calves fed the control diet (TMRI). Significantly best values were achieved by calves fed the 30% followed by 20% dietary DDGS instead of soybean meal and yellow corn. Results of digestibility trials indicated that rams fed the control diet (TMRI) had significantly (P<0.05) lower digestibility coefficients, nutritive values and nitrogen utilization compared with other diets. No significant differences were observed (P<0.05) among the experimental groups in ruminal pH and the obtained values were within the normal ranges (6.70-6.84). Ammonia–N concentration was greater in control diet but, there was a linear decrease in ammonia–N concentration as the level of DDGS increased in the diets. Supplemented rations with DDGS showed significant increase in the level of TVFA's. Increasing level of DDGS in diets of calves' increased TP concentrations, being the lowest in TMRI (control), while albumin and globulin recorded insignificant differences among all diets. The values of AST were higher significantly (P<0.05) in rations containing DDGS than that of control. Values of serum- creatinine and cholesterol were not affected by dietary treatments. Blood parameters studied indicated normal physiological and healthy status of all experimental calves. Total body gain and daily gain were increased quadratically (P<0.05) with increasing DDGS replacement. Calves fed diets containing 20% or 30% DDGS recorded the best feed conversion values followed by 20% DDGS.
It may be concluded that inclusion of DDGS with a rate of 30% from soybean meal and yellow corn in buffalo calves diet result in better net revenue, economical efficiency and feed cost per kg daily gain.