Effects of different levels of methionine in pre-starter diets on immunity function and DNA methylation in broilers

The study was carried out to determine the effects of different levels of methionine in Pre-starter diets on PPAR gene expression and immune function of broiler chickens. Methionine (Met) is necessary to achieve a fast growth rate in chickens. A total of 240 Ross 308 broilers were equally assigned to 8 treatments with 3 replicates. The treatments included T1: diet with 20% methionine less than Ross catalog recommendation. T2: Standard diet in accordance with the recommendations of the Ross catalog. T3, T4, T5, T6, T7 and T8: diets with 20, 40, 60, 80, 100 and 120 % methionine more than Ross catalog recommendation. The results showed that there was a significant difference in the expression of PPAR gene with the difference in diet Met levels in the 8 groups (P<0.05). PPAR controls the expression of several genes involved in the proliferation and differentiation of adipose tissue cells. Gene expression in broiler chickens with Met deficiency and excess may have compensated for this deficiency and excess in the birds. Also, the results indicated that increasing in the levels of Met in pre-starter diets of chickens the antibody production against ND increased significantly (P<0.05). Besides, the antibody production against IBD increased significantly (P<0.05). Furthermore, the antibody production against H9N1 not affected (P>0.05). Studies suggest that dietary protein deficiency reduces the concentration of most amino acids in plasma and compromises the immune system. Totally it is suggested that the high levels of Met in the diet maybe beneficial and it needs more studies.