Effects of Long-Term Protein Restriction on Meat Quality and Muscle Metabolites of Shaziling Pigs

Background: It has been demonstrated that low-protein diets can improve the meat quality of pork. This study aimed to investigate the effects of long-term protein restriction from piglets to finishing pigs for 24 weeks on meat quality and muscle metabolites of Shaziling pigs. Results: Compared to the control group, reducing dietary protein levels by 20% reduced the L* value (p < 0.05), increased the a* value (p < 0.01), and tended to decrease pressing loss (p = 0.06) of longissimus thoracis muscle (LTM). Furthermore, compared to the control group, the −20% group had significantly lower levels of muscular danazol, N,N-dimethyl-Safingol, and cer(d18:0/14:0) (p < 0.05), all of which were positively associated with the L* value and negatively associated with the a* value (p < 0.05). Therefore, danazol, N,N-dimethyl-Safingol, and cer(d18:0/14:0) might be potential biomarkers for meat color. Conclusions: These results indicated that reducing dietary crude protein by 20% for 24 weeks could improve meat quality and alter muscular metabolites of Shaziling pigs, and the improvement in meat quality might be ascribable to decreased danazol, N,N-dimethyl-Safingol and cer(d18:0/14:0).