Hyperplastic response of adipose tissue to caloric overconsumption in sexually mature chickens

Two experiments were conducted to determine the hyperplastic response of adipose tissue from sexually mature chickens in response to caloric overconsumption. In the first experiment, birds were either force-fed or allowed to consume feed ad libitum, whereas in the second experiment, a feed-restriction regimen was also implemented. In both experiments feeding treatments were applied for 19 consecutive days, and a diet high in energy and low in protein was fed to all birds to promote lipogenesis. To monitor adipocyte dynamics, birds in Experiment 1 received an intramuscular injection of [methyl-3H]thymidine on Day 15, whereas in Experiment 2 birds were injected on Days 1 and 10. In both Experiments 1 and 2, body weight gain and percentage weight gain were greater in the force-fed birds. Furthermore the retroperitoneal (abdominal), and right sartorial fat depots increased in weight as a result of force-feeding, and there were concomitant increases in total adipocyte DNA content and total radiotracer uptake by these tissues. The results indicate that expansion of adipose tissue in sexually mature chickens is not restricted solely to cellular hypertrophy, but periodic hyperplastic activity also occurs in response to caloric overconsumption.