Effect of rumen-protected betaine and choline on carcass characteristics, amino acid and fatty acid composition of Ao-hu sheep

This study aimed to evaluate the effects of dietary supplementation with rumen-protected betaine (RPB) and rumen-protected choline (RPC) on carcass traits, amino acid composition, and fatty acid composition of Ao-hu sheep. A total of 96 sheep were randomly assigned to four groups. The trial lasted for 105 days, comprising a 15-day adaptation phase followed by a 90-day experimental period. The experimental diets consisted of 2.5 g/d RPB, 0.25 %/kg RPC, and a combination of 2.5 g/d RPB with 0.25 %/kg RPC. Compared to the control group (the sheep fed on the basal diet without adding RPB and RPC), all experimental groups demonstrated a significant increase in crude fat (CF) and total amino acids (TAA) in the longissimus thoracis (LT) muscle. Notably, the RPB × RPC group exhibited significant interactions that affecting dressing percentage (DP) and crude protein content (CP) (P < 0.05). Additionally, saturated fatty acids (SFA) significantly decreased, while monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) increased in the LT muscle across all treatments (P < 0.05). The combination of RPB and RPC also had significant interactive effects on total amino acids, SFA, PUFA, and MUFA in the LT muscle. Therefore, supplementation with either RPB or RPC improved carcass traits, reduced shear force, enhanced the content of umami amino acids, essential amino acids, and total amino acids, and decreased the proportion of unsaturated fatty acids. As a result, both the tenderness and nutritional value of the meat were enhanced, leading to an overall improvement in meat quality. The combined supplementation of RPB and RPC yielded the most pronounced effects.