Evaluation of a part of the dietary methionine substitution by betaine on fatty acid synthase gene expression in laying hens under heat stress

Current study was performed to evaluate a part of the dietary methionine substitution by betaine on fatty acid synthase gene expression in laying hens under heat stress. Present study was conducted in a completely randomized design (CRD) with a 2 ×2 factorial experiment using 96 (65-week) hens in Line strains W36. First factor was done with 2 dietary treatments with 2 levels; 100% methionine, 87% methionine and 13% betaine and second factor with 1 level without heat stress and 1 with (salon with 35 oC); (Salon with 23 oC) with 4 treatments and 3 repetition (8 birds in each repetition). To achieve appropriate stress, the hens were daily exposed under 35 oC for 6 hours. After 2 month of feeding, 4 birds were eventually slaughtered and fatty acid synthase gene expression was assessed by means of specific primer and real time PCR analysis. The results indicated that addition of betaine to died and exposure heat stress caused a significant decline in fatty acid synthase gene expression being 1.98 and 2.15 fold in liver tissue, respectively (P