The effect of increasing dietary fat levels on hepatic lipogenesis in growing chicks was investigated. Increasing the level of dietary fat resulted in a linear depression of both acetate-1-14C and glucose-U-14C incorporation into fatty acids and glyceride-glycerol. Increasing the dietary fat level increased the activity of NADP-isocitrate d ehydrogenase. Chicks fed fat-free diet had lower (P<0.05) activity of NAD-malic dehydrogenase than those fed diets containing 5%, 10% and 15% fat. Activity of glucose-6-phosphate dehydrogenase was higher (P<0.05) in chicks fed fat-free diet. The increase of the level of dietary fat resulted in a linear increase in non-esterified fatty acids in serum. The inverse relationship between the rate of fatty acid synthesis and the level of non-esterified fatty acids in serum suggested a role for non-esterified fatty acids in the control of fatty acid synthesis. Jap. J. Zootech. Sci., 50 (2) : [100][101][102][103][104][105][106][107] 1979 We have previously reported that increases of dietary protein levels resulted in a depression in capacity for hepatic fatty acid synthesis in growing chicks1). On the other hand, the increase of the level of dietary fat has been reported to depress fatty acid synthesis in both liver 2-4) and adipose tissue 5-7) of the laboratory rat. The lipogenic effects could be attributed to dietary component since the increase of dietary fat is generally associated with a decrease in carbohydrate levels. The work of HILL et al.4), however, suggests that dietary fat has a specific inhibitory effect on hepatic lipogenesis unrelated to a reduced carbohydrate intake. Also, the effect of dietary fat on lipogenesis in growing chick liver has been studied but only to a cerain extent .Hence, in the present experiment, we have studied the effects of dietary fat level on in vitro lipogenesis as measured by the incorporation of acetate-1-14C or glucose-U-14C into fatty acid by liver slices of the growing chicks . In addition, the activities of NAD-malic dehydrogenase, NADP-isocitrate dehydrogenase and the pentose pathway dehydrogenases were also studied. Day-old male White Leghoon chicks obtained from a local hatchery were used for the experiment. They were raised on wire floors. Feed and water were made available at all times. Upon reaching the age of 28 days old, all the chicks were weighed individually and divided into 4 groups. Thereafter, they were randomly distributed to the different treatment with 5 birds assigned to each treatment.The birds were housed in portable wire battery from where ad libitum supply of feed and water was freely accessible. Body weight and feed consumption were determined at weekly intervals. The chicks were fed the experimental diets for 21 days. The four groups were fed purified diet containing 0%, 5%, 10% and 15% fat, respectively. The composition of the purified diets is shown in Table 1.At the termination of the 3-week experimental period, all the chicks were weighed for their final body weight and then sacrificed one by one b...

50, Cyanocabalamin 0.5, Lactose 91893.5 (mg/ 100g. mixture). 1) Probability of a significant difference by t-test. NS=Not significant.