Lipogenesis and body fat in chicks: effects of calorie-protein ratio and dietary fat.
Two experiments were conducted with battery-reared, broiler chicks from day-old through 19 or 20 days of age. In each experiment, body weight, feed consumption, liver weight, liver fat, body fat, in vivo lipogenesis, and the hepatic activities of the lipogenic enzymes, acetyl-Coenzyme A carboxylase (ACC) and fatty acid synthetase (FAS), were measured. In Experiment 1, four diets having calorie-protein (C/P) ratios expressed as kilocalories of metabolizable energy per kilogram of diet per percent crude protein of 120, 139, 158, or 177 were used. Growth was decreased with ratios above 139. The C/P ratio had no significant effect on feed conversion, liver weight, liver fat, or FAS activity. In vivo lipogenesis and ACC activity were increased by C/P ratios above 120. Body fat increased with increasing C/P ratios, but only the C/P 177 diet produced significantly fatter chicks. In Experiment 2, four diets containing total fat 2.0, 4.1, 6.3, or 8.6% at a constant C/P ratio of 139 were used. All fat levels above 2.0% improved growth and feed conversion. Fat levels had no effect on liver weight, liver fat, or body fat. In vivo lipogenesis and ACC and FAS activities decreased with increasing dietary fat. The data indicate that C/P ratio affects body fat by increasing lipogenic activity as the ratio is increased. Although dietary fat depressed lipogenesis, the depression appears to be offset by increased availability of fatty acids from the diet for deposition in adipose tissue. Hence, added dietary fat does not change body fat content.(ABSTRACT TRUNCATED AT 250 WORDS)
D000273:Adipose Tissue / Q000378:metabolism*; D000818:Animals; D001835:Body Weight; D002645:Chickens / Q000378:metabolism*; D004041:Dietary Fats / Q000378:metabolism*; D004044:Dietary Proteins / Q000008:administration & dosage*; D002149:Energy Intake; D004734:Energy Metabolism; D008055:Lipids / Q000096:biosynthesis*; D008099:Liver / Q000033:anatomy & histology / Q000378:metabolism; D009929:Organ Size
D004041:Dietary Fats; D004044:Dietary Proteins; D008055:Lipids