Abstract
Two experiments were conducted to investigate the effects of exogenous catalase (CAT) in the diet of weaned piglets on growth performance, oxidative capacity, and hepatic apoptosis after challenge with lipopolysaccharide (LPS). In experiment 1, 72 weaned piglets [Duroc × Landrace × Yorkshire, 6.90 ± 0.01 kg body weight (BW), 21 d of age] were randomly assigned to be fed either a basal diet (CON group) or a basal diet supplemented with 2,000 mg/kg CAT (CAT group; dietary CAT activity, 120 U/kg) for 35 d. Blood samples were collected on day 21 and day 35. At the end of this experiment, 12 pigs were selected from each of the CON and CAT groups, and six pigs were injected with LPS (50 μg/kg BW), while the remaining six pigs were injected with an equal amount of sterile saline, resulting in a 2 × 2 factorial arrangement of treatments (experiment 2). Blood samples and rectal temperature data were collected 0 and 4 h after challenge, and liver samples were obtained after evisceration. The gain-to-feed ratio was higher (P < 0.05) in piglets in the CAT group than in those in the CON group from day 1 to 35. Catalase and total superoxide dismutase (T-SOD) activities were higher (P < 0.05), whereas malondialdehyde (MDA) concentrations were lower (P < 0.05), in piglets in the CAT group than in those in the CON group at day 35. During challenge, rectal temperature and liver MDA and H2O2 concentrations increased significantly (P < 0.05), whereas plasma CAT and glutathione peroxidase (GSH-Px) activities and liver CAT activity decreased markedly (P < 0.05), in LPS-challenged piglets 4 h post-challenge. Increased CAT activity and decreased MDA concentration were observed in the plasma and liver of piglets in the CAT group 4 h post-challenge (P < 0.05). Dietary CAT supplementation markedly suppressed the LPS-induced decrease in plasma GSH-Px activity and liver CAT activity to levels observed in the CON group (P < 0.05) as well as significantly decreasing the concentration and mRNA expression of caspase-3 and caspase-9 (P < 0.05). LPS-induced liver injury was also attenuated by dietary CAT supplementation, as demonstrated by a decrease in liver caspase-3 mRNA expression (P < 0.05). Overall, dietary supplementation with 2,000 mg/kg exogenous CAT (dietary CAT activity, 120 U/kg) improves growth performance and has a beneficial effect on antioxidant capacity in weaned piglets; alleviates oxidative stress and reduces liver damage by suppressing hepatic apoptosis in LPS-challenged piglets.