The effect of varying dietary manganese and selenium levels on the growth performance and manganese-superoxide dismutase activity in nursery pigs

Antioxidant activity in the weaned piglet is important for the developing animal at a cellular level. This study examined the impact of varying dietary levels of manganese and selenium on piglet growth performance and plasma manganese superoxide-dismutase (MnSOD) specific activity. Weaned piglets were blocked by weight (N = 216; 5.21 ± 1.17 kg; 21 ± 3 d) and sex (2 barrows and 2 gilts/pen). Pens (n = 9 pens/treatment) within a block were randomly assigned to dietary treatments in a 2 × 3 factorial design to examine the effect of adding different levels of Mn (0, 12, and 24 mg/kg added Mn from MnSO4 when pigs were fed diets containing 2 levels of Se (0.1 and 0.3 mg/kg added Se from Na2SeO3). Diets were fed in three phases (P1 = d 1–7, P2 = d 8–21, P3 = d 22–35). Pigs and orts were weighed weekly and blood collected on d 0, 7, 21, and 35 for analysis of red blood cell MnSOD. Data were analyzed via the GLM procedure of SAS. No Mn x Se interactions were observed. There was a linear response (P < 0.05) in overall average daily gain across dietary Mn levels. There was a linear trend (P < 0.10) in overall average daily feed intake across Mn levels. Gain to feed ratio (d 0–35) was not impacted by Mn or Se (P > 0.10). MnSOD activity in RBC increased from d 0–7, peaked at d 7, and decreased until d 35. On d 7, diets with 12 mg/kg Mn significantly increased (P < 0.05) MnSOD specific activity (0.91 IU/mg) compared to diets with 24 mg/kg Mn (0.67 IU/mg) but did not differ from diets with 0 mg/kg Mn (0.87 IU/mg). The dietary treatment that maintained specific MnSOD activity was 12 mg/kg Mn and 0.1 mg/kg Se supplemented, while ADG was maximized in diets with 24 mg/kg Mn supplemented.