Effects of Chromium Methionine Supplementation with Different Sources of Zinc on Growth Performance, Carcass Traits, Meat Quality, Serum Metabolites, Endocrine Parameters, and the Antioxidant Status in Growing-Finishing Pigs.

This experiment was conducted to evaluate the effects of chromium methionine with/without zinc sulfate or zinc amino acid complex on the growth performance, carcass traits, meat quality, serum parameters, endocrine parameters, and antioxidant status of growing-finishing pigs. A total of 180 (32.0 ± 1.7 kg body weight, BW) crossbred pigs (Duroc × Landrace × Yorkshire) were used in a completely randomized design with three dietary treatments and 10 replicates per treatment (five pens of barrows and five pens of gilts with six pigs per replicate). Three treatments were corn-soybean meal-based diets supplemented with 100 mg Zn/kg from zinc sulfate (ZnSO), 100 mg Zn/kg from ZnSO + 0.2 mg Cr/kg from chromium methionine complex (CrMet), or 50 mg Zn/kg from ZnSO + 50 mg Zn/kg from zinc amino acid complex (ZnAA) + 0.2 mg Cr/kg from CrMet, respectively. The experiment lasted 105 days, of which was divided into three stages including phase 1 (30 to 50 kg BW), phase 2 (50 to 80 kg BW), and phase 3 (80 to 110 kg BW). Results showed that supplementation with CrMet and ZnAA improved (P < 0.05) the feed conversion of the pigs in phase 2, phase 3, and the overall experiment. Hot carcass weight, dressing percentage, and a longissimus dorsi muscle area were increased (P < 0.05) in pigs fed with diets supplemented with both CrMet and ZnAA compared with pigs fed with diets containing only ZnSO (P < 0.05). There was also an increase (P < 0.01) pH in the longissimus dorsi muscle in pigs fed with diets supplemented with CrMet and ZnAA. The concentration of serum glucose in pigs fed with diets containing CrMet and ZnAA was decreased (P < 0.05) compared with that in pigs fed with the diet containing ZnSO. Supplementation with CrMet and ZnAA increased (P < 0.05) the circulating levels of insulin and decreased (P < 0.05) cortisol. There was an increase (P < 0.05) in total serum antioxidant capacity and Cu/Zn superoxide dismutase activity as well as a decrease (P < 0.05) in serum malondialdehyde concentrations in pigs fed with diets supplemented with CrMet and ZnAA compared with pigs fed with the diet supplemented only with ZnSO. In conclusion, supplementation of CrMet only or CrMet together with ZnAA improved feed conversion, carcass traits, and meat quality in the growing-finishing pigs.