EFFECT OF DIETARY MANGANESE ON LIPID OXIDATION OF EGG YOLK AND ANTIOXIDATIVE STATUS OF LAYING HENS

Abstract

The purpose of this experiment was to examine the effect of feed supplementation with various manganese sources on the oxidative stability of egg yolk during storage and some parameters of antioxidative protection in laying hens. Obviously, the performance parameters of laying hens were evaluated too. Twenty-weeks-old laying hens of Lohmann Brown breed were randomly allocated to 4 treatments with 6 replicates of 4 hens in each. For the subsequent 8 weeks the birds were fed the identical basal diet supplemented with equivalent dose of Mn (30 mg/kg) from various sources. Group 1 (control) was given the unsupplemented basal diet (BD) with only background Mn level of 51.7 mg/kg dry matter. Diets for groups 2, 3 and 4 consisted of same BD supplemented with Mn in the form of Mn-sulphate, Mn-proteinate (Mn-Prot) and Mn-glycine chelate (Mn-Gly), respectively. During the entire experiment, the daily feed intake of birds was not affected by dietary treatments. Egg production was significantly increased in group supplemented with Mn-Gly. The feed supplementation with Mn-sulphate resulted in significantly lower egg weight than in birds fed diet with equivalent Mn dose from Mn-Gly and BD only. The feed to egg mass ratio was significantly elevated in group supplemented with Mn-sulphate compared to all experimental groups. Lipid oxidation of egg yolks during cold storage was affected by dietary manganese. The malondialdehyde (MDA) values of egg yolk were started to increase in different storage time (in Group 1, 3 and 4 at 20th, 20th and 30th storage days respectively) during 40 days of cold storage. Lipid oxidation in egg yolks of hens fed diet enriched with Mn-sulphate was stable during entire storage period. Although there were no significant differences in MDA values among the treatments until 30 days of storage, Mn-sulphate group showed significantly lower MDA concentration compared to Mn-Gly group after 40 days of storage. Intake of BD enriched with Mn-sulphate resulted in significatly higher activity of glutathione peroxidase in blood and total antioxidant status in plasma of laying hens. The dietary Mn intake did not influence the activity of superoxide dismutase and MDA concentration in liver. The presented results showed that diet supplementation with inorganic form of manganese may improve the oxidative stability of egg yolk. The adequate supplementation of diet with Mn has positive effect on the antioxidative status of laying hens.