Effects of Corn–Soybean Meal-Based Fermented Feed Supplementation on Growth Performance, Meat Quality, Fatty Acid Profiles, Nutritional Values, and Gut Microbiota of Lean-Type Finishing Pigs

This research investigated the impact of corn–soybean meal-based fermented feed on the growth performance, pork quality, and fatty acid profiles of lean-type finishing pigs. A total of 80 lean-type growing DLY (Duroc × Landrace–Yorkshire) pigs were randomly assigned to 2 groups, with 5 replicates of 8 pigs per pen. The pigs in control group (CON group) were fed a basal diet, while the pigs in fermented feed group (FF group) were fed a diet supplemented with 10% fermented feed. The experimental period lasted 70 days. Results exhibited that pigs in FF group had a significant increase in final body weight and average daily gain (ADG) (p < 0.05) and had a significant decrease in the feed-to-gain ratio (F/G) (p < 0.05). The FF group also exhibited significant promotion in muscle intramuscular fat content, marbling score, and meat color and significantly reduced the meat shear force and drip loss (p < 0.05). Serum analysis indicated that fermented feed significantly elevated blood glucose, total cholesterol, triglyceride levels, and serum hormones such as insulin, leptin, and IGF-1 (p < 0.05). Additionally, fermented feed significantly elevated the levels of polyunsaturated fatty acids (PUFAs) and monounsaturated fatty acids (MUFAs), whereas it decreased the saturated fatty acids (SFAs) contents (p < 0.05). The fermented feed also significantly enhanced pork nutritional values (p < 0.05). The fermented feed increased the expression of IGF-1, SREBP1c, PDE3, PPARγ, SCD5, and FAT/CD36 mRNA (p < 0.05). Furthermore, microbial 16S rDNA analysis uncovered that FF supplementation significantly reduced the Campilobacterota phylum abundance, while increasing the genus abundances of Clostridium_sensu_stricto, norank_f_Oscillospiraceae, unclassified_c_Clostridia, and V9D2013 (p < 0.05). In summary, the results indicated that the microbial fermented feed exhibited the regulation effects on pork quality and nutritional values of lean-type pigs through regulating lipid metabolism and gut microbial composition.