TNF and Hepatic steatosis: Compared with pigs supplemented with 0% glycerol, 0% vitamin C and 0% niacinamide, pigs supplemented only with 10% glycerol had higher (p < 0.05) TNF-α concentration, partially hepatic steatosis, higher (p < 0.05) relative abundances of Escherichia_shigella, Prevotellaceae_UCG_003, Lachnospiraceae_XPB1014_group, Coprococcus, Lactococcus and Megamonas, lower (p < 0.05) solute carrier family 7 member 11 (SLC7A11) expression in liver tissue.