[Studying the effect of different levels of methionine and fat on some economical traits of broilers]

ABSTRACT

The effect of 3 levels of methionine [NRC recommended, 5 percent more than NRC recommended and 10 percent more than NRC recommended] and 2 levels of fat [0 and 5 percent] on some economical traits [performance and carcass] of broilers using a 2x3 factorial experiment with completely randomized design based on two rearing stages, starter [0-3 wk] and grower [4-6 wk] was studied, ANOVA of the effects of dietary treatments on traits and Duncan's multiple range test to compare means revealed that methionine levels had significant effect on live weight gain and improvement of feed conversion ratio in starter [p<0.05], grower and total period [p<0.01]. Fat had no significant effect on live weight gain and feed conversion ratio in starter [p>0.05]. Carcass traits were not significantly affected by different levels of fat [p>0.05] but methionine levels decreased abdominal fat yield and increased breast yield significantly [p<0.05]. The interactions between methionine and fat levels were not significant [p>0.05]. Therefore it can be concluded that using methionine up to 10 percent more than NRC recommended and fat up to 5 percent of diet, except in starter, is recommendable in broiler diets