Effect of Different Dietary Buffer Sources and Roughage-to-Concentrate Ratios on Growth Performance, Rumen Fermentation, and Health Status of Growing Lambs

Abstract

A total of 90 Barki lambs (average body weight: 24.43 kg) were randomly and equally allotted into nine groups to assess the role of dietary buffer addition on growth performance, rumen fermentation, and overall health status. The lambs were fed diets with different roughage-to-concentrate (R:C) ratios: 60:40, 40:60, and 20:80. Within each R:C ratio, three dietary treatments were applied: no buffer (control), sodium bicarbonate, and sodium bentonite supplementation. Groups 1, 2, and 3 were fed the 60R:40C diet with no buffer, sodium bicarbonate, and sodium bentonite, respectively. Groups 4, 5, and 6 received the 40R:60C diet with the same buffer treatments, and Groups 7, 8, and 9 were fed the 20R:80C diet under the same supplementation conditions. Results showed that, within the 60R:40C group, both buffers improved (P≥0.05) body weight (BW), total gain (TG), total feed intake (TFI), and feed conversion ratio (FCR), while significantly (P<0.05) increasing rumen total volatile fatty acids (TVFAs), intestinal villi length, phagocytic activity, and serum bactericidal activity. These treatments also significantly reduced serum lysozyme activity and rumen ammonia nitrogen (NH3-N) levels. In the absence of buffer supplementation, the 40R:60C diet resulted in improved BW, TG, intestinal villi length, and reduced TFI, leading to improved FCR. It also enhanced phagocytic and bactericidal activities and lowered lysozyme levels. This ratio did not significantly affect rumen pH. However, the 20R:80C diet significantly reduced rumen pH. Supplementation of buffers in the 20R:80C group improved BW, TG, villi length, TVFAs, and concentrations of acetic and propionic acids. It also reduced rumen NH₃-N and mitigated the negative impacts of high concentrate feeding on rumen pH while lowering TFI and improving FCR. Overall, the 40R:60C ratio supplemented with sodium bicarbonate yielded the most favorable outcomes in terms of growth performance and rumen health. Therefore, we recommend this combination for optimal productivity in growing lambs.