EFFECT OF DIFFERENT FORMS OF POLYUNSATURATED FATTY-ACIDS ON DUODENAL AND SERUM FATTY-ACID PROFILES IN SHEEP

Four sheep cannulated in the rumen and proximal duodenum were used in a 4 x 4 cross-over design to investigate the effects of ruminal fatty acid (FA) infusion on duodenal and serum FA profiles. The diets were c omposed of 85.7% natural grassland hay and 8.6% concentrate supplement ed with 5.7% soy oil for diet SO, 5.7% emulsified soy oil for diet ESO , 6.7% calcium salts of soy or palm FA for diets CaSSO and CaSP, respe ctively. Diets were formulated to be isonitrogenous and isoenergetic; total FA content in dry matter was 6.4-6.6%. Characteristics of rumina l fermentation were not affected by source or physical form of FA. The proportion of stearic acid in the duodenal flow (% of the total C-18) was high compared with total diet, e.g., 49.8 vs. 3.5 and 54.3 vs. 9. 4% for soy and palm diets, respectively. Ruminal biohydrogenation and unsaturated FA was lower for CaS diets than for SO and ESO diets (48.7 and 60.9 vs. 81.2 and 94.7%, for oleic and linoleic acids, respective ly). As a result, trans-vaccenic acid levels in duodenal flow and seru m (% or total FA) were lower for the CaS diets than for SO and ESO die ts (8.3 vs. 36.0% and 0.9 vs. 7.8%, respectively). Unsaturated FA as C aS were partly protected against ruminal biohydrogenation, and can be effective in increasing intestinal absorption of unsaturated FA.