Effect of dietary lysine level on lipogenesis in broilers

From 3-7 weeks of age, male and female broilers were fed ad libitum on 1 of the 8 experimental diets. These diets were isoenergetic (13.6 kJ/kg) and isoproteic (186 g/kg) and provided 7 to 14 g/kg lysine. The growth performances, the abdominal fat proportion and hepatic malic enzyme activity (malate dehydrogenase with decarboxylating EC 1.1.1.40) were measured. All parameters varied when dietary lysine concentration was increased from 7 to 9 or to 11 g/kg. The lysine requirement in the finishing period for minimum abdominal fat proportion was higher than for minimum feed conversion ratio, itseful higher than for maximal growth rate. Malic enzyme activity varied with abdominal fat proportion, and this variation could explain the reduction in fatness. However, an excess of lysine did not amplify the reduction of fat deposit.