The effect cinnamon bark polyphenol extract at different levels on performance, carcarss parameters, and abdominal adipose tissue dynamics in broiler chickens

The purpose of this study was to evaluate the effects of cinnamon bark polyphenols (TPE) on fattening performance, slaughter and carcass traits, and the expression levels of peroxisome proliferator-activated receptor gamma (PPARγ) and lipoprotein lipase (LPL), which play key roles in adipogenesis and are critical adipogenic regulatory factors during different developmental stages of broiler chickens fed for 42 days. A total of 288 one-day-old male Ross 308 broiler chicks were divided into three groups. The first group was fed a basal diet (control group - C) without any additives, while the second (TPE300) and third (TPE600) groups were fed isoenergetic and isonitrogenous compound diets supplemented with 300 mg/kg and 600 mg/kg cinnamon bark polyphenol extract, respectively. Abdominal adipose tissue samples were collected from one chick in each subgroup at 7, 14, 35, and 42 days of age. In broiler chickens fed with TPE-supplemented diets, body weight gain and feed intake during the periods of 1-21, 22-42, and 1-42 days were significantly lower compared to the control group (P<0.05). Additionally, the feed conversion ratio was negatively affected in the TPE600 group compared to the other groups (P<0.05). TPE supplementation in mixed diets decreased slaughter weight, hot carcass weight, and the rate of abdominal adipose tissue while increasing of the gizzard rate in slaughter weight (P<0.05). The treatment groups reduced hot carcass yield and the proportional weight of breast muscle (P<0.05). The rate of abdominal adipose tissue generally showed an increasing trend with age, and the effects of TPE supplementation on adipose tissue rate were significant. TPE supplementation also reduced adipocyte size compared to the control group (P<0.05). The supplementation of TPE reduced serum triglyceride levels while significantly increasing serum insulin and leptin concentrations (P<0.05). Additionally, the expression levels of PPARγ, which regulates insulin sensitivity and lipid metabolism in adipocytes, and LPL, which accelerates fat catabolism, were significantly increased in adipose tissue, reflecting their role in the adipogenesis process. In conclusion, the increase in LPL and PPARγ gene expression in abdominal adipose tissue, along with the reduction in serum triglyceride levels and the increase in serum leptin and insulin concentrations due to TPE supplementation, indicates that these coordinated responses play a significant role in regulating lipid metabolism in broiler chickens.