An experiment was conducted using 300 ducks of day-old (180 Muscovy and 120 Moulard), based on sexing which was done for 500 ducklings at the first day of age where it was brought up in accordance with the principles of the French care for birds research and rearing of water fowls for fattening purposes until 12 weeks of age. At this age birds were divided within each breed according to feeding regime (forced feeding and ad libitum feeding group), and supplementation of L carnitine (1000 mg kg of diet) making eight groups until the end of the study (at 14 weeks). The results of the experiment revealed that, forced feeding has a significant increase in body weight and absolute or relative weight gain (5954.33 g, 1421.03 g and 23.51%, respectively) than ad libitum feeding (4506.75 g, 411.05 g and 8.94%; respectively). Under the regime of force-feeding Moulard ducks had significantly increased absolute and relative body weight gain (1808.16 g and 29.64%, respectively) than Muscovy ducks (930.67 g and 15.73% respectively). Feed conversion per kg increase in weight was the best in Moulard ducks than Muscovy under force-feeding regime (6.29 kg and 11.5 kg, respectively), and vice versa with the ad libitum feeding (18.89 for 11.06 kg, respectively), at the same time the Moulard ducks needed a larger amount of feed per kg liver, (in forced or ad libitum feeding) than Muscovy. El-Edel M.A. et al., 812 Force-feeding led to severe assembly of fat in the liver, which was significantly higher than in ad libitum feeding groups (57.78% from 35.28%, respectively) and on the contrary, was the percentage of protein (9.66% from 28.81%, respectively). Addition of L carnitine to the feed at forced feeding period resulted in a significant increase in the life weight (5731.97 g) than in non L carnitine fed group(5400.13 g), on the other hand other performance traits not affected significantly by the addition of L carnitine in feed. Liver weight (absolute and Percent) in L carnitine treatment group was higher than non L carnitine group in the ad libitum feeding group (it was not significant). Using L carnitine in ad libitum feeding groups achieved a higher percentage of dry matter in liver (30.88%) than those without L carnitine (28.98%), unlike the breast muscles; dry matter was higher in the group without L carnitine than with L carnitine (32.05% from 30.37%). It would be concluded from this study that using of Moulard duck is preferred for the foie gras production than Muscovy ducks because of its ability to receive large quantity of feed and has the highest feed conversion and a better feed per kg increase in weight as well as the absolute and relative weight of the liver from Muscovy ducks under the forced feeding regime. L carnitine supplementation has no effect on the foie gras production, but if it was added to the feed during the forced feeding period it improved live weight significantly.