Effects of Rumen-Protected β-Alanine on Hepatic Gluconeogenesis-Related Indices and Muscle Energy Metabolism in Transported Cattle.

Preslaughter nutritional strategies that preserve energy reserves in transported beef cattle may help maintain normal post-mortem muscle metabolism and meat quality. β-alanine, a carnosine precursor, enhances glucose metabolism and glycogen reserves. This study evaluated the effects of rumen-protected β-alanine (RP-β-Ala) on meat quality, hepatic gluconeogenesis-related indices, and muscle energy metabolism in long-distance transported cattle. Thirty-six healthy 18-month-old Simmental crossbred bulls (627 ± 41 kg) were randomly assigned diets containing 0 (control) or 96 g/head/d RP-β-Ala. After 28 days of feeding, serum was sampled from six bulls per group. Following a 2-day rest (RP-β-Ala supplementation continued), these twelve bulls were transported, slaughtered, and sampled. Transport significantly increased serum lactate dehydrogenase (LDH) and creatine kinase (CK). The transport × RP-β-Ala interaction significantly affected serum superoxide dismutase (SOD). Post-slaughter tissue indices were analyzed solely for the effect of RP-β-Ala supplementation, as all slaughtered bulls underwent transportation. Compared to controls, the RP-β-Ala group exhibited significantly higher muscle pH_{45 min} and an accelerated pH decline rate within 24 h post-mortem in both M. longissimus dorsi (LD) and M. semitendinosus (ST) muscles. In LD muscle, hardness, shear force, gumminess, and chewiness significantly decreased, while ATP content and HK, PFK, PK, and LDH activities significantly increased. In ST muscle, lactate content and GP, HK, PFK, and LDH activities significantly increased. In the liver, glucose, lactate, ATP, and ADP contents significantly increased, alongside enhanced G-6-Pase and pyruvate carboxylase (PC) activities. Dietary RP-β-Ala supplementation may regulate energy metabolism in transported cattle by enhancing muscle glycolytic activity and indices associated with hepatic gluconeogenic capacity, thereby improving selected meat-quality traits.