Effects of replacing dietary maize grains with increasing levels of sugar beet pulp on rumen fermentation constituents and performance of growing buffalo calves

This study was conducted to evaluate the effects of replacing cracked maize with increasing levels of sugar beet pulp (SBP) on nutrients digestibility, blood biochemical and rumen fermentation constituents and animal performance of growing Egyptian buffalo calves. Forty male Egyptian buffalo calves (237.2 ± 24.46 kg of initial body weight, IBW) were allocated into a completely randomized design and stratified to one of four experimental diets. The basal diet was isonitrogenous (40:60 forage: concentrate) and was formulated to contain 60% of dietary DM cracked maize replaced by ascending levels of SBP (0, 333, 667, and 1000 g/kg respectively). The study lasted for a period of 143 days from which 21 days for adaptation while the remaining 122 days were used for data collection. Increasing the level of SBP resulted in a quadratic increase (P = 0.017) in the average daily gain (ADG) with a linear tendency of increase (P = 0.064) in dietary dry matter intake. A quadratic decrease of feed conversion ratio (FCR, P = 0.005) was observed with the ascending levels of SBP. In addition, the daily intake of organic matter, neutral detergent fiber assayed with heat stable α-amylase and corrected for ash (aNDFom), acid detergent fiber corrected for ash (ADFom) were quadratically (P < 0.01) improved upon increasing the dietary SBP level while the daily intake and digestibility of ether extract were declined linearly (P < 0.01). Replacing SBP for maize resulted in linear increase (P < 0.01) in OM, aNDFom, cellulose and hemicellulose digestibility coefficients. Ruminal pH, total short chain fatty acids, proportions of acetate (C2) and butyrate were increased linearly (P < 0.05). In contrast, the proportions of propionate (C3) and isobutyrate were decreased linearly (P < 0.05) upon increasing the levels of SBP. In addition, the C2:C3 ratio and total protozoa were linearly (P < 0.01) increased while the ruminal NH3-N concentration was quadratically (P = 0.046) increased as SBP replaced maize in the diet. Furthermore, upon increasing the dietary SBP levels, the blood urea-N, cortisol and thyroxin (T4) concentrations were quadratically elevated (P < 0.01). Conversely, linear decreases in creatinine, (P = 0.027) and cholesterol (P = 0.001) concentrations were found. In addition, blood insulin like growth factor-1 (IGF-1) concentration increased linearly (P = 0.006) as SBP level increased. Feeding cost based on BW gain was linearly reduced (P = 0.043) by 25%, causing the overall profits ($/head/d) to be quadratically (P < 0.01) increased. Overall, the obtained results indicate that replacing maize grains with up to 667 g SBP/kg diet resulted in a highest profit by 21%, enhanced ruminal fermentation, nutrients digestibility and ADG and reduced FCR. Therefore, this study could be economically feasible for use in fattening diets of growing Egyptian buffalo calves without impairing animal performance or health.