Estimation of net nutrient oxidation and lipogenesis in growing pigs

Data from previous series of trials were reevaluated in order to quantify t he net nutrient oxidation and lipogenesis by combining data from balance ex periments and indirect calorimetry measurements. The experiments were carri ed out with eight castrated males of Danish Landrace measured individually from 30 to 100kg BW. All pigs were fed alternately on high feeding level, n ear ad libitum and on low feeding level, near maintenance. Oxidation of car bohydrate (OXCHO) and fat (OXF) was calculated from gas exchange measuremen ts. On high feeding level the contribution from OXCHO and OXF to the total heat production was 55 and 30%, respectively, at 30kg BW and fairly constan t from 60 kg BW with OXCHO around 80% and no net OXF. At low feeding level the contribution from OXCHO and OXF was 28 and 63%, respectively, at 30 kg BW, increasing to 52% for OXCHO and decreasing to 37% for OXF at 95 kg BW. The lipogenesis on high feeding level increased from 2.4 to 11.9 MJ/d, whil e on low feeding level it increased from 2.5 to 3.6 MJ/d at 30 to 95 kg BW. The intake of carbohydrate was too low to cover energy requirement by OXCH O on low feeding level and in the first periods on high feeding level and O XF occurred. In spite of a deficit of carbohydrate for oxidation a part of carbohydrate (2.6MJ/d,similar to 150g/d) was used for fat synthesis, indica ting an importance of lipogenesis in growing pigs.