There is significant interest in improving the efficiency of beef production. Beef quality and consumer satisfaction are of equal importance. Feeding zinc (Zn) above nutritional recommendations and feeding ractopamine hydrochloride (RH) can be utilized to optimize cattle growth. However, the impacts of these rapid growth strategies on beef quality are not fully understood. This study aimed to identify variations in the protein and metabolite profile of muscle from cattle-fed Zn and RH that may influence postmortem characteristics of meat. Cattle were fed one of the following diets: control (CON-NO), RH-only supplementation (CON-RAC), supranutritional Zn-only supplementation (SUPZN-NO), and the combination of Zn and RH supplementation (SUPZN-RAC). At harvest, RH supplementation resulted in muscle with a greater pH at 6 h postmortem and increased toughness at 1 d postmortem. Zn supplementation resulted in muscle with a lower pH at 6 h and more tender steaks at 1 d postmortem. Postmortem muscle from cattle supplemented with Zn and RH differed in energy metabolism, stress response, and structural proteins. Further, supplementation led to observed differences in metabolites related to energy production. Variations in the protein and metabolite profiles may have influenced postmortem energy metabolism, impacting pH decline, protein degradation, and tenderness development at 1 d postmortem from cattle supplemented Zn and RH. ZN supplementation may have promise in improving tenderness at 1 d postmortem.

Read the full article in the Journal of Animal Science.