This experiment was carried out to investigate the mechanism of action of mulberry leaf extract (MLE) in reducing abdominal fat accumulation in female broilers. A total of 192 one-day-old female Arbor Acres (AA) broilers were divided into 4 diet groups, with each group consisting of 8 replicates with 6 birds per replicate. The diets contained a basal diet and 3 test diets with supplementation of 400, 800, or 1,200 MLE mg/kg, respectively. The trial had 2 phases that lasted from 1 to 21 d and from 22 to 56 d, respectively. The growth performance, abdominal fat deposition,
fatty acid composition, serum biochemistry and
mRNA expression of genes related to fat metabolism in liver were determined. The results showed that, 1) dietary supplementation with MLE had no significant impact on broilers final
body weight, average daily gain (ADG), or feed to gain ration (F/G) (P > 0.05), but linearly reduced abdominal fat accumulation in both experimental phases (P < 0.05); 2) the total contents of
monounsaturated fatty acids (MUFA) and
polyunsaturated fatty acids (PUFA), such as
palmitoleic acid,
oleic acid, and eicosadienoic
acid, were increased quadratically as a result of dietary supplements of 400, 800, and 1,200 mg/kg MLE (P < 0.01), while the total contents of
saturated fatty acids (SFA), such as teracosanoic
acid were decreased (P < 0.01); 3) the addition of 800 or 1,200 MLE mg/kg to the diet linearly reduced total
cholesterol (TC) in the serum and liver (P < 0.05).
Adenosine-activated
protein kinase (AMPK)
mRNA expression in the liver was quadratically increased by the addition of 800 or 1,200 MLE mg/kg to the diet (P < 0.05), and the
mRNA expression of
sterol regulatory element binding protein-1c (
SREBP-1c),
acetyl-CoA carboxylase (ACC), and
acetyl-CoA carboxylate),
fatty acid synthase (FAS) were linearly decreased (P < 0.05). In conclusion, MLE can be employed as a viable fat loss feed supplement in fast-growing broiler diets since it reduces abdominal fat deposition in female AA broilers via the AMPK/
SREBP-1c/ACC signaling pathway. MLE can also be utilized to modify the
fatty acid profile in female broilers (AA) at varied inclusion levels.