Dose-dependent effects of rumen-protected betaine on the quality characteristics of longissimus Lumborum muscle in fattening lambs during extended freezing storage

This study investigated the effects of rumen-protected betaine (RPB) supplementation on the quality attributes of Longissimus lumborum (LL) muscle in fattening lambs during extended frozen storage. Following the fattening period, 32 lambs were randomly selected for meat quality analysis. The experimental groups were as follows: (1) CTRL (control): no dietary RPB; (2) RPBL: 2 g RPB per head per day; (3) RPBM: 4 g RPB per head per day; and (4) RPBH: 6 g RPB per head per day, during the fattening period. Meat samples were stored at −18 °C for up to nine months, and physicochemical properties, including color, water-holding capacity (WHC), drip loss, cooking loss, Warner-Bratzler shear force (WBSF), lipid peroxidation, and antioxidant enzyme activities, were analyzed at different time points. RPB supplementation improved WHC (P < 0.05), with the RPBH group exhibiting the highest retention of intracellular water throughout storage. Drip and cooking losses were markedly reduced in the RPB-supplemented groups, particularly RPBM and RPBH, indicating improved protein stability and reduced oxidative damage. Additionally, RPB supplementation enhanced meat tenderness, as evidenced by lower WBSF values in treated groups (P < 0.05). Overall, this study highlights RPB as a functional feed additive that enhances meat quality and extends shelf life under frozen conditions. Future research should explore the underlying molecular mechanisms, including oxidative stress markers and proteolytic enzyme activity, to further elucidate RPB's role in meat preservation.