Effects of zinc supplementation and betaine substitution to methionine on hepatic betaine - homocysteine methyltransferase and lipogenic genes expression in laying hens under heat stress

To investigate the effects of dietary zinc and betaine (Bet) substitution to methionine (Met) on hepatic betaine - homocysteine methyltransferase (BHMT) and lipogenic (malic enzyme and fatty acid synthase) genes expression in laying hens under heat stress by using real-time qPCR, an experiment was performed with 288 Hy-line W-36 leghorn (at 50 to 62 weeks of age) in complete randomized design (CRD) with a 3×2×2 factorial arrangement of treatments including twelve treatments, 3 replicates and 8 hens in each replicate. There were 6 dietary treatments: three doses of Bet (0, 13 and 26%) substitute to Met combined with three levels of zinc (90 and 100 mg/kg) supplemented to the basal diets that were combined with two environmental conditions (thermoneutral and heat stress conditions). Results showed that dietary supplemental zinc had no effect on BHMT, malic enzyme and fatty acid synthase (FAS) genes expression. The results confirmed that Bet substitution to methionine due to a 2.11-fold increase (P