EFFECT OF DIETARY BETAINE AND LOW METHIONINE ON MULARD DUCK PERFORMANCE, BLOOD PARAMETERS AND LIPOGENESIS GENE EXPRESSION

The effects of dietary methionine and betaine (Bet) on productive performance, blood biochemical parameters and mRNA expression levels of fat acid synthase (FAS) and acetyl-CoA carboxylase (ACC), were investigated in Mulard ducks which raised in summer season. Three hundred one-day old healthy Mulard ducklings with similar body weight were randomly distributed into six groups with five replicates per treatment and ten ducks per replicate. Six diets were prepared as following: control diet (C); low methionine diet (ML); diet supplemented with Bet (0.25% Bet); diet supplemented with Bet (0.5% Bet); diet supplemented with 0.25% Bet and low in methionine (0.25% Bet + ML); diet supplemented with 0.5% Bet and low in methionine (0.5% Bet + ML). Regarding allover growth performance results revealed that increasing dietary Bet significantly increased ( P <0.05) body gain of ducks by 13% when compared with the control diet, moreover both groups fed on 0.5% Bet and 0.5%Bet +ML diet exhibited the improved feed conversion ratio (1.88 and 1.93, respectively) when compared with control (2.13) and ML (2.29) groups. Inclusion of Bet either in control or ML diet significantly increased carcass yield, breast and thigh meat yield percent and decreased breast, thigh skin and abdominal fat percent. Nutrient digestibility was improved by adding Bet even in ML diet. Serum total lipids, triglycerides and total cholesterol constituents were significantly decreased in all group supplemented with Bet. Dietary Bet significantly decreased ( P <0.05) mRNA expression of fatty acid synthase, acetyl-coA carboxylase genes, this decline was more obvious in control group with Bet than in ML with Bet. In conclusion, the role of Bet in ML diet was clear by improving productive performance of ducks, thus Bet can partially replace methionine in duck’s diet. Key words: Betaine; methionine; performance; carcass; lipogenesisgenes; Mulard ducklings