Using mixed silages of sweet sorghum and alfalfa in total mixed rations to improve growth performance, nutrient digestibility, carcass traits and meat quality of sheep

Combining sweet sorghum (SS) with alfalfa for ensiling has the potential to make a high-quality silage with relatively a better nutrient balance. However, the existing data are insufficient about how changes in ratios of SS to alfalfa in different silage mixtures affect animal performance and meat quality. Therefore, the objective of this study was to determine the effect of feeding total mixed rations containing mixed silages of SS and alfalfa on growth performance, nutrient digestibility, carcass traits and meat quality of Karakul sheep. Five total mixed rations were formulated with different SS proportions at 100%, 80%, 60%, 40%, and 20% on a fresh weight basis. Thirty 4-month old male Karakul sheep with 25.5 ± 1.4 kg BW were randomly allocated into five treatment groups, each with six lambs for this experiment. The results indicated that the Karakul sheep consuming total mixed rations containing SS-Alfalfa (SS-AF) silage mixtures with a lower proportion of SS tended to increase nutrient digestibility, growth performance, carcass traits, and meat quality. Feeding diets with SS at 40% and 20% inclusion rate showed a significant linear increase in the apparent digestibility of DM, CP and NDF, as well as subcutaneous fat thickness and water holding capacity (P < 0.5). Moreover, reduction in SS inclusion rate in these diets caused significant (P < 0.05) linear and quadratic increases in DM intake, final BW, average daily gain, carcass weight, and the amino acid contents of meat (P < 0.05). Conversely, feeding diet with lower SS inclusion rate led to decrease in feed conversion ratio and shear force significantly (P < 0.05) for these sheep. It appears that 40% inclusion of SS was the optimal rate in making the SS-AF silage mixture for lambs to achieve a superior production performance and high-quality meat products in Karakul sheep. However, further research is needed to investigate the effect of feeding SS-AF silage mixtures alongside contrasting ingredients on rumen function, ruminal microorganisms and digestive enzyme activity of sheep and other ruminant animals.