اثر جایگزینی متیونین گیاهی با متیونین سنتزی در جیره های کم پروتئین بر عملکرد، خصوصیات لاشه، پاسخ های ایمنی و برخی از فراسنجه های خونی جوجه های گوشتی

This study was conducted to evaluate the effect of different levels of herbal methionine in low protein diet on performance, carcass characteristics, immune response and some blood parameters in broiler chickens. In this experiment 240 day-old Ross 308 mixed broiler chicks were randomly divided into 6 groups with 4 replicates and 10 birds each in a completely randomized design. Treatments included: standard commercial diet with 100% synthetic methionine (DL-methionine) and low protein diet with different levels of herbal methionine (0, 15, 30, 45 and 60 percent) replaced with synthetic methionine respectively in grower (11 to 24 days of age) and finisher periods (25 to 41 days of age).Decreasing protein level significantly reduced feed intake in finisher and whole periods and reduced body weight gain in finisher period of the experiment (p<0.05). With increasing herbal methionine levels up to 60 % in low protein diet, feed conversion ratio significantly increased and body weight gain decreased in finisher and whole periods of the experiment (p<0.05). Decreasing dietary protein level, increased abdominal fat percentage and blood TG, cholesterol and VLDL concentrations at 41 days of age. Results of the present study indicated that herbal methionine could be replaced instead of synthetic methionine in low protein diet in grower and finisher diets of broiler chicks without any adverse effect on feed conversion ratio.