Effects of Probiotic-Fermented Corn Wet Distillers Grains on the Growth Performance, Carcass Characteristics, and Heavy Metal Residue Levels of Finishing Pigs

This study evaluated the effects of dietary probiotic-fermented corn wet distillers grains (FCWDGs) on finishing pigs. Three Bacillus subtilis strains (CGMCC21218, CCTCC2022073, and CICC10275) were used to ferment corn wet distillers grains, yielding FCWDGs-1, FCWDGs-2, and FCWDGs-3. A total of 128 130-day-old Anqing six white pigs were randomly assigned to four groups: a control group and groups supplemented with 6% FCWDGs-1 (T1), FCWDGs-2 (T2), and FCWDGs-3 (T3). Over a 60-day trial, FCWDGs significantly enhanced growth performance, with T1 and T3 groups showing higher final weight and average daily gain (ADG) compared to the control (p < 0.05), and feed-to-gain ratios were reduced in all treatments (p < 0.05). Loin muscle depth (LMD) was significantly greater in all treatments (p < 0.05), and the lean meat percentage (LMP) was significantly higher in the T1 group (p < 0.05). Antioxidant activity (T-AOC, SOD, and GSH-Px) was enhanced in all treatments, with the highest values observed in the T1 group (p < 0.05). Notably, FCWDGs reduced heavy-metal residues (As, Pb, Cu) in muscle, liver, and kidney tissues, particularly in the T1 group. The results highlight the potential of Bacillus subtilis-fermented FCWDGs to enhance growth performance and carcass traits, and reduce heavy metal accumulation in pig tissues.