Bacillus subtilis and Enterococcus faecium co-fermented feed alters antioxidant capacity, muscle fibre characteristics and lipid profiles of finishing pigs

Abstract

This study aimed to assess how Bacillus subtilis and Enterococcus faecium co-fermented feed (FF) affects the antioxidant capacity, muscle fiber types, and muscle lipid profiles of finishing pigs. In this study, a total of 144 Duroc × Berkshire × Jiaxing Black finishing pigs were randomly assigned into 3 groups with 4 replicates (12 pigs per replication). The three treatments were a basal diet (0% FF), basal diet + 5% FF, and basal diet + 10% FF, respectively. The experiment lasted 38 days after 4 days of acclimation. The study revealed that 10% FF significantly increased the activity of superoxide dismutase (SOD) and catalase (CAT) compared to 0% FF group, with mRNA levels of upregulated antioxidant-related genes (GPX1, SOD1, SOD2, and CAT) in 10% FF group. 10% FF also significantly upregulated the percentage of slow-twitch fiber and the mRNA expression of MyHC Ⅰ, MyHC IIa, and MyHC IIx, and slow MyHC protein expression while reducing MyHC IIb mRNA expression. Lipidomics analysis showed that 5% FF and 10% FF altered lipid profiles in longissimus thoracis. 10% FF particularly led to an increase in the percentage of triglycerides (TGs). The Pearson correlation analysis indicated that certain molecular markers such as PA (49:4), Hex2Cer (d50:6), CL (72:8) and PC (33:0e) could be used to indicate the characteristics of muscle fibers and were closely related to meat quality. Together, our findings suggest that 10% FF improved antioxidant capacity, enhanced slow-twitch fiber percentage, and altered muscle lipid profiles in finishing pigs.