Nutritive physiological effect of dietary fats in rations for growing swine. 2. Effect of an isocaloric exchange of carbohydrate energy versus fat energy in piglets on growth and various metabolic parameters in the subsequent fattening period

: The influence of different feeding regimes of piglets on fattening performance and blood composition of the subsequent fattening period (30-100 kg) was examined. Three groups of pigs fed on an isocaloric and isonitrogenous basis with rations containing either 5% fat (groups I), 18% fat (group II) or 35% fat (group III) until body weight of 30 kg, were fed ad libitum one diet from 30 kg onwards. At a body weight of 45 and 93 kg the blood concentrations of insulin, glucose, urea, free fatty acids, neutral lipids and cholesterol in response to feeding and of insulin and glucose in response to an oral glucose load was determined in pigs provided with a permanent jugular vein catheter. Moreover, the in-vitro fat synthesis from glucose was measured. At the end of the experiment the body composition was determined by chemical analysis of the carcass. Neither feed intake, daily body weight gain nor feed conversion differed significantly among the groups. Blood urea levels of the three groups did not suggest a different protein utilization. Neither feed consumption nor oral intake of glucose affected the insulin and glucose response of the three groups differently. The concentrations of free fatty acids, neutral lipids and cholesterol did not differ clearly among the groups although occasionally significance of difference was observed. In group I the in-vitro synthesis of fat was increased (p less than 0.05) at a body weight of 45 kg and appeared to be higher at a body weight of 93 kg as compared to the high fat group (group III). No clear differences between the groups were observed in the chemical composition of the carcasses. It is concluded, that isocaloric replacement of carbohydrates by fat in the diet of piglets does not affect protein and fat retention in the subsequent fattening period.