پیامد تزریق درون تخم‌مرغی سطوح مختلف دی‌ال-‌متیونین بر ویژگی‌های لاشه و فراسنجه‌های خونی جوجه‌های گوشتی یک‌روزه

Methionine is the first limiting amino acid in poultry which has a primary role in stimulating protein synthesis and growth. This study was designed to investigate the effect of dietary intake of different levels of DL-methionine on hatchability, carcass characteristics, and blood parameters of day-old Ross 308 broiler chicks. For this purpose, 240 fertile broiler breeder eggs were used in a completely randomized design with eight treatments and 30 eggs per treatment. The experimental treatments included injection of different levels of DL-methionine (0.19, 0.38, 0.57, 0.76, 0.95, and 1.14 %) dissolved in 1 ml sterile distilled water, along with a sham-control group (sterile water injection) and a control group (non- injected). After hatching, the chickens were weighed and blood samples were taken and slaughtered to measure carcass characteristics. In ovo injection of different levels of DL-methionine caused a reduction in hatchability (P<0.01), especially by 1.14 % DL-methionine treatment. Based on the results, in ovo injection of DL-methionine increased carcass weight, carcass yield, thigh weight, relative thigh weight, proventriculus weight, liver weight, and relative liver weight (P<0.05). In ovo feeding of DL-methionine increased serum protein concentration (P<0.01), whilst decreased serum glucose and urea concentration (P<0.01). Hatchling weight, serum cholesterol and triglyceride oncentrations, and also immune system organs weight were not affected by treatments (P>0.05). The overall results of the present study indicated that regardless of low hatchability in methionine treatments, in ovo injection of 0.76% DL-methionine had the best growth response and then, is an advisable level of this experiment.