Micelle silymarin supplementation to fattening diet augments daily gain, nutrient digestibility, decreases toxic gas emissions, and ameliorates meat quality of fattening pigs

To evaluate the impact of micelle silymarin (MS) on fattening pig growth, nutrient digestibility, toxic gas emissions and meat quality, 140 crossed fattening pigs were allocated to four treatments with seven repetition pens [(two barrows and three gilts)/pen] per treatment from the initial body weight of 51.0 kg (SD 2.86). The pigs were fed the basal diet containing 0%, 0.05%, 0.1%, and 0.2% MS for 10 weeks. The results showed a linear improvement in the average daily gain (ADG) of pigs during 5 to 10 weeks as the dietary MS dose increased (P = 0.041). The apparent total tract digestibility of nitrogen (N) was enhancive linearly (P = 0.017 and 0.031, respectively) in week 5 and week 10 as the dietary MS dose increased. The Lactobacillus populations in the faeces of pigs fed MS diets were linearly increased (P = 0.048) during week 5. The dietary supplement of MS decreased faecal H2S concentrations in week 5 and NH3 concentrations in week 10 (quadratic, P = 0.022 and 0.007, respectively). Moreover, dietary MS linearly diminished cooking loss (P = 0.010) and yellowness value at 45 min postmortem (P = 0.029), whereas the redness value linearly increased (P = 0.028 and 0.002, respectively) after 45 min and 24 h postmortem. Finally, the linear decrease (P < 0.001) of thiobarbituric acid reactive substance (TBARS) concentration and protein carbonyl in pigs fed MS diets was found, but a quadratic improvement (P < 0.031) of total antioxidant capacity (T-AOC) concentration was observed in the meat samples from MS-treated pigs. Taken together, supplementation of the graded level of MS to the basal diet exhibited dose-independent responses on ADG, N digestibility, toxic gas emissions and meat quality. Among the tested doses, 0.2% MS supplementation in the diet is found to be the most effective dose.