Effect of Increasing Dietary Energy on Hepatic Lipogenesis in Growing Chicks

The effect of increasing the energy content of the diet through supplementation of various levels of fat or protein on hepatic lipogenesis and activities of associated enzymes of liver was examined in force-fed growing chicks. Hepatic lipogenesis was significantly decreased as the dietary metabolizable energy level was increased through supplementation of fat or protein. The activity of nicotinamide adenine dinucleotide phosphate-malate dehydrogenase (NADP-MDH) (EC 1.1.1.40) in liver was higher (P less than .01) in chicks fed diets containing the lowest energy level. The activity of citrate cleavage enzyme (EC 4.1.3.8) in liver was significantly depressed as the dietary metabolizable energy level increased through supplementation of fat, whereas increasing the dietary metabolizable energy level through protein supplementation resulted in a significant increase in citrate cleavage enzyme activity in liver. Nonesterified fatty acid concentration in serum was significantly increased as the dietary metabolizable energy level was increased through supplementation of fat.