Effects of dietary manganese on antioxidant status, biochemical parameters and thickness of intestinal mucus in laying hens

The objective of this study was to investigate the effects of different sources of manganese (Mn) on the antioxidant status, some biochemical parameters and thickness of intestinal mucus in laying hens. Ninety-six 20-week-old hens of the Lohman Brown strain were randomly divided into four groups; each group was replicated six times with four hens per replicate. Hens in the control group were fed the basal diet (BD) with natural background Mn level of 45.5 mg/kg feed. For the three experimental groups, the BD was supplemented with 120 mg Mn/kg either from Mn-sulphate or Mn-chelate of protein hydrolysate (Mn-Bioplex) or Mn-chelate of glycine hydrate (Mn-Glycinoplex). After eight weeks of dietary treatment, a tendency towards increasing activity of superoxide dismutase (SOD) in the erythrocytes was observed in all experimental groups. The results showed that inorganic Mn source increased the glutathione peroxidase activity in the hens' blood (P < 0.05). The intake of Mn-Bioplex resulted in significantly increased total antioxidant status in the plasma of hens in the group (P < 0.05) compared to the control group. The plasma biological antioxidant potential was increased in the treatment groups supplemented with Mn-sulphate (P < 0.01) and Mn-Bioplex (P < 0.05). The total cholesterol concentration was decreased (P < 0.05) in the group fed the diet supplemented with Mn-Glycinoplex, as compared with the control. Moreover, the mucus layer thickness in the jejunum was reduced in the groups of birds fed with the organic form of Mn (P < 0.001, P < 0.05), as well as with the inorganic form of Mn (P < 0.001). These results indicate that the addition of dietary Mn was effective in improving the biological antioxidant potential, decreasing total plasma cholesterol and reducing the thickness of adherent intestinal mucus gel in the jejunum of laying hens.