Paul J. Wangsness

Effects of feeding, fasting and refeeding on growth hormone and insulin in obese pigs ☆

This study has indicated that temporal patterns of plasma GH changes were similar in lean and obese pigs with one to two secretory spikes occurring during a 6-hour period. Fasting caused increased GH in both pig strains; however, obese pigs, compared to lean, had lower GH during feeding and fasting. This depressed plasma GH of obese pigs may not be due entirely to impaired pituitary function since refeeding caused increased GH to levels similar to lean pigs. Insulin response per unit of feed intake was greater in obese pigs compared to lean. Together with higher insulin to glucose ratios, these results indicate hyperinsulinemia in the obese pigs. Overall, hormone and glucose responses were influenced by the nutritive status--fed, fasted or refed. Therefore consideration of feeding schedule was important in assessment of hormonal differences between the lean and obese pigs.

Feeding behavior of lean and obese pigs

Abstract Daily feeding behavior was characterized in ad lib fed lean Yorkshire and obese Ossabaw pigs from 12 to 14 weeks of age. Obese pigs consumed more feed per unit body weight, spent more time eating per day, and exhibited a slower rate of eating compared to lean pigs. Diurnal distribution of feeding bouts also differed in the two pig strains with obese pigs exhibiting a tendency to equalize feeding activity over a 24-hr period. The nature of these differences in feeding behavior and their possible relationship with metabolic processes and endocrine status characteristic of obesity were discussed.

Effect of age on hyperphagia in the genetically obese Zucker rat.

Summary Two experiments were conducted to determine if and when hyper-phagia occurs in the genetically obese Zucker rat. In Experiment 1, lean and obese rats were offered food ad libitum from 7 to 19 weeks of age. Obese rats consumed significantly more total food than lean rats throughout the experiment. However, when food intake (FI) was expressed per unit of body weight (FI/BW) to compensate for the large differences in body weight between lean and obese rats, hyperphagia in the obese rats was only evident from 7 to 10 weeks of age. Thereafter, FI/BW became similar and at 19 weeks of age, FI/BW was significantly lower for obese rats compared to leans. Experiment 2 studied younger rats (3 to 11 weeks of age) and produced similar results. However, the increased FI/BW in obese rats was more pronounced at the early age and was evident from 3 to 7 weeks of age. It is concluded that obese rats were hyperphagic compared to lean rats, but only at an early age.