EFFECT OF FISH-OIL AND OLIVE OIL OVERFEED ING ON THERMOGENESIS IN SOWS

A trial on total metabolism was conducted in eight nonpregnant, nonlac tating sows over eight periods, each of 16 days duration, to measure p otential fatty acid induced thermogenesis. During the first and last e xperimental periods, the animals received a basal ration which just co vered the energy maintenance requirement. In the second to seventh per iods supplements of olive oil, fish oil, or puffed wheat starch as ref erence nutrient were added to the diet in random sequence at two level s up to 50 % above the maintenance requirement. All rations were calcu lated with reference to the sows' initial weight and remained quantita tively unchanged throughout the experiment. The animals were fed twice daily. During each metabolism period a complete energy balance was as sessed for all sows by means of collection technique (feed, feces, uri ne), and 48-h measurements of the gas exchange in a respiration chambe r. The sows' body mass increased linearly during the course of the exp eriment by 5.8 kg per period. The three supplement types had no influe nce on the animals' final body weight, wich averaged 205.5 kg with the starch supplement, 204.8 kg with olive oil, and 205.8 kg with fish oi l. Energy digestibility (DE/GE) was 100 % for all three supplements, a nd metabolizability of energy (ME/GE) one percentage point less. Carbo n and energy depositions showed a pronounced linear relationship to th e level of supplementation and were also influenced by the type of sup plement. Heat production was 20.9 MJ/d after feeding the basal ration alone and, taking the average of the two supplementation levels, 21.6 MJ for the starch supplement, 21.0 MJ for olive oil, and 20.6 MJ for f ish oil. The relationship between energy deposition and the supply of ME resulted in regression coefficients of 0.9 MJ/MJ after feeding star ch and 1.0 MJ/MJ after feeding the two oils. It can be concluded from these results that supplementation of the diet with fat containing mon o- or polyunsaturated fatty acids above the energetic maintenance requ irement under conditions of severely restricted movement (respiration chamber) has no influence on thermogenesis and consequently causes a d eposition of energy equivalent to the amount supplied with the dietary fat.