Evaluation of different levels of organic (met-Mn) and inorganic (MnSO4) form of Mn on ‎performance, egg quality and blood metabolites of Hy line W36 layer hen under heat stress ‎condition

In this study, the effect of two sources (met-Mn and MnSO4) and three-level of manganese (25, 90, 135 mg/Kg) was evaluated on performance, egg quality and blood parameters in Hy-line w36 laying hens under heat stress condition. The experimental treatments contained basal diet with; 25 mg/Kg MnSO4 (treatment 1), 90 mg/Kg MnSO4 (treatment 2), 135 mg/Kg MnSO4 (treatment 3), 25 mg/Kg met-Mn (treatment 4), 90 mg/Kg met-Mn (treatment 5), or 135 mg/Kg met-Mn (treatment 6). A total of 360 hens, 22 weeks of age, were used in a 2×3 factorial arrangement in a completely randomized design with 6 treatments and 4 replicates (15 hens per replicate). Our results showed that Mn source had no significant effect on production traits but higher Mn level significantly improved egg production, feed conversion and egg mass (P<0.05). The use of organic source or increasing dietary Mn level significantly decreased feed intake (P<0.05). The sources and levels of dietary had no significant effect on the weights of egg white and yolk, but the level of Mn had significant effect on shell weight, albumin height, and serum Mn and phosphorus. Although Mn source did not affect the blood metabolites, but the serum superoxide dismutase activity significantly increased in groups that consumed organic Mn (P<0.05). In conclusion, supplementary Mn at 135 mg/kg from any source especially chelated form, may increase production performance and egg quality traits in the early pre-peak production phase of laying hen, under heat stress condition.