Dietary L-arginine supplementation beneficially regulates body fat deposition of meat-type ducks.

1. Unlike mammals, uricotelic species, such as the duck, cannot synthesise endogenous arginine (Arg). This study was conducted to test the hypothesis that dietary L-Arg supplementation might regulate body fat deposition in ducks without affecting their fast growth rate. 2. A total of 160 21-d-old male and female White Pekin ducks were assigned randomly to two treatments: a non-supplemented control and supplementation at 10 g/kg L-Arg of a maize and soybean meal-based diet. 3. The 3-week feeding trial showed that the addition of L-Arg had no significant effect on feed intake, but significantly increased body weight gain by 5·2 %, breast muscle weight relative to live body weight by 9·9%, carcase crude protein content by 9·2%, ether extract content in breast muscle by 11·9%. Arg supplementation significantly decreased skin with fat and abdominal fat pad contents by 7·6% and 4·9% respectively and the ether extract content of carcase by 7·2%. 4. The results of this study indicate that a diet with 10 g/kg supplemental L-Arg could reduce the fat deposition of carcase and abdominal adipose cell size (diameter and volume), enhance intramuscular fat in breast muscles, as well as increase muscle and protein gain. The decreased fat depot in the carcase may be attributed to a reduction of hepatic lipogenic enzyme activity.