Effects of an oat-based high-fibre diet on insulin, glucose, cortisol and free fatty acid concentrations in gilts

Abstract

AbstractTo understand the mechanism underlying the effect of high-fibre diets on feeding motivation and stereotypic behaviour in pigs, non-pregnant gilts were given either concentrate or a high-fibre diet based on oat hulls and blood samples were assayed for cortisol, glucose, insulin and free fatty acids. The duration of eating was much longer for gilts on the high-fibre diet than gilts given concentrates. Concentrations of cortisol increased with food delivery and this was most pronounced with the concentrate diet. Concentrations of free fatty acids decreased before feeding and those of glucose and insulin decreased temporarily immediately after feeding began. The diet had no marked effect on these changes, although the decrease for insulin was less evident for the concentrate diet. As feeding continued, free fatty acid concentrations decreased, while concentrations of insulin and glucose increased. The increase in glucose and insulin was fastest with the concentrate diet, although post-feeding peak values did not differ. Postprandial cortisol and free fatty acid concentrations did not differ between diets. There was no evidence of a pre-prandial cephalic phase insulin or glucose response to feeding in the gilts although concentrations of both hormones decreased immediately after the gilts began to eat. The high-fibre diet tended to delay the peak glucose and insulin response to meals, suggesting that the reduced feeding motivation following consumption of high-fibre diets does not involve the same mechanism as the increased satiety following increased energy intake. As well as reducing the occurrence of ster eoty pies, high-fibre diets decrease cortisol concentrations at feeding.