Objective  To investigate the effects of oregano oil addition in the diet on abdominal fat deposition and fat metabolism of Tianlu yellow-feathered chicken, and verify the effect of oregano oil reducing abdominal fat rate of broiler through production simulation experiment.

Method  In laboratory experiment, twenty-four 65-day-old female Tianlu yellow-feathered chickens were selected. Each chicken was weighed and numbered, then randomly divided into three groups with eight chickens of each group according to the principle of weight similarity. Each chicken was fed in single cage. The control group was fed with basal diets (without oregano oil), while the other two groups were fed with diets containing 100 and 200 mg/kg oregano oil respectively for 30 days after 3 days’ pre-feeding. The chickens were fed by free eating and free drinking. In production simulation experiment, total 270 65-day-old female Tianlu yellow-feathered chickens were randomly divided into three groups according to the principle of weight similarity after weighing and numbering, with six replicates in each group and 15 chickens per replicate. All experiment protocols were the same as laboratory experiment. The chickens were weighed after the laboratory experiment to calculate production performance. Then the chickens were slaughtered to collect blood, liver, abdominal fat, breast muscle and leg muscle samples and determine slaughter performance, serum biochemical indicators and mRNA expression levels of fat metabolism related genes. After the production simulation experiment, the chickens were weighed and sampled to determine production and slaughter performances, and verify the results of the laboratory experiment.

Result  In laboratory experiment, compared with the control, 200 mg/kg oregano oil addition significantly increased Tianlu yellow-feathered chicken average daily weight gain and breast muscle rate, significantly reduced feed to gain ratio and abdominal fat deposition, with abdominal fat reduction rate of 23.51%. Adding 200 mg/kg oregano oil to the diets significantly reduced mRNA expression levels of fat synthesis related genes in liver of Tianlu yellow-feathered chicken, but had no obvious effect on fat decomposition related genes. The results of production simulation experiment conformed to those of laboratory experiment, and validated the effect of oregano oil reducing abdminal fat deposition. Compared with the control group, the abdominal fat reduction rate reached 20% in 200 mg/kg oregano oil addition group.

Conclusion  The 200 mg/kg oregano oil addition can significantly reduce abdominal fat deposition of Tianlu yellow-feathered chicken by reducing the synthesis of fatty acids in liver.