Effect of dietary manganese supplementation on abdominal fat deposition of broilers1

Excessive abdominal fat deposition seriously restricts the production efficiency of broilers. Several studies found that dietary supplemental manganese (Mn) could effectively reduce the abdominal fat deposition of broilers, but the underlying mechanisms remain unclear. The present study aimed to investigate the effect of dietary supplementation with the inorganic or organic Mn on abdominal fat deposition, and enzyme activity and gene expression involved in lipid metabolism in the abdominal fat of male or female broilers. A total of 420 1-d-old AA broilers (half males and half females) were randomly allotted by body weight and gender to 1 of 6 treatments with 10 replicate cages of 7 chicks per cage in a completely randomized design involving a 3 (dietary Mn addition)×2 (gender) factorial arrangement. Male or female broilers were fed with the Mn-unsupplemented basal diets containing 17.52 mg Mn kg-1 (d 1-21) and 15.62 mg Mn kg-1 (d 22-42) by analysis or the basal diets supplemented with 110 mg Mn kg-1 (d 1-21) and 80 mg Mn kg-1 (d 22-42) as either the Mn sulfate or the Mn proteinate with moderate chelation strength (Mn-Prot M) for 42 d. The results showed that the interaction between dietary Mn addition and gender had no impact (P>0.05) on any of the measured parameters; abdominal fat percentage of broilers was decreased (P<0.003) by Mn addition; Mn addition increased (P<0.004) adipose triglyceride lipase (ATGL) activity, while Mn-Prot M decreased (P<0.002) the fatty acid synthase (FAS) activity in the abdominal fat of broilers compared to the control; Mn addition decreased (P<0.009) diacylglycerol acyltransferase 2 (DGAT2) mRNA expression level and peroxisome proliferator-activated receptor γ (PPARγ) mRNA and protein expression levels, but up-regulated (P<0.05) the ATGL mRNA and protein expression levels in the abdominal fat of broilers. It was concluded that dietary supplementation with Mn inhibited the abdominal fat deposition of broilers possibly via decreasing the expression of PPARγ and DGAT2 as well as increasing the expression and activity of ATGL in the abdominal fat of broilers, and Mn-Prot M was more effective in inhibiting the FAS acitivity.