Effects of dietary fat source and green tea (Camellia sinensis) extract on genes associated with lipid metabolism and inflammatory responses in female broiler chickens

Abstract

This study was aimed to investigate the effects of dietary fat sources and green tea extract (GTE) on gene expression associated with lipid metabolism and inflammation in broiler chicken. A total of 300 female Ross 308 broiler chicks were allocated to six dietary treatments in a completely randomised design with a factorial arrangement of two levels of GTE (0 and 500 mg/kg diet) × three levels of fat inclusion [without fat (control group), soybean oil (SO) and tallow (Ta)]. Liver fat (LF), liver methallothionin (LMT) content, and lipoprotein lipase (LPL), adipose triglyceride lipase (ATGL), tumour necrosis factor α (TNF-α), and interleukin (IL-6)] genes expression were investigated. Relative expression and statistical analyses of genes expression were assessed using REST software. The effect of added dietary fats was significant and improved performance parameters compared to the control group (p < .05). The highest abdominal fat and blood triglyceride, and the lowest carcase yield, were achieved in chicks fed SO-supplemented diet (p < .05). Chicks fed a diet supplemented with SO showed an overexpression and a decrease of LPL and ATGL compared to the Ta-supplemented and control groups, respectively (p < .05). GTE supplementation was effective on LPL and ATGL expression and ameliorated the effect of SO on abdominal fat percentage. TNF-α expression, LMT content, and relative weight of lymphoid organs were affected neither by GTE nor by the fat sources. There was no detection of IL-6 gene expression in adipose tissue. The results of this study demonstrated that diets rich in SO were capable increase fat deposition by an increase and decrease in LPL and ATGL gene expression, respectively. However inclusion of GTE in broiler diets alleviated the LPL-increasing and ATGL-reducing effects of SO and ameliorated the effect of SO on abdominal fat mass.Highlights Diets supplemented with SO increased abdominal fat mass by changes in LPL and ATGL gene expression. Obesity was not effective in the expression of inflammatory genes (TNF-α and IL-6), indicating a lack of connection between inflammation and obesity in broiler chicken. GTE (500 mg/kg diet) addition to the diets supplemented with SO ameliorated the effect of SO on LPL and ATGL gene expression and abdominal fat mass.

Keywords

• adipose tissue
• dietary fat source
• fat deposition
• gene expression
• green tea extract