INCORPORATION OF N-3 FATTY-ACIDS OF FISH OIL INTO TISSUE AND SERUM-LIPIDS OF RUMINANTS

This study examines the biohydrogenation and utilization of the C20 and C22 polyenoic fatty acids in ruminants. Eicosapentaenoic (20:5n-3) and docosahexaenoic (22:6n-3) acids were not biohydrogenated to any significant extent by rumen microorganisms, whereas C18 polyenoic fatty acids were extensively hydrogenated. The feeding of protected fish oil increased the proportion of 20:5 from 1% to 13-18% and 22:6 from 2% to 7-9% in serum lipids and there were reductions in the proportion of stearic (18.0) and linoleic (18:2) acids. The proportion of 20:5 in muscle phospholipids (PL) increased from 1.5% to 14.7% and 22:6 from 1.0% to 4.2%; these acids were not incorporated into muscle or adipose tissue triacylglycerols (TAG). In the total PL of muscle, the incorporated 20:5 and 22:6 substituted primarily for oleic (18:1) and/or linoleic (18:2) acid, and there was no consistent change in the porportion of arachidonic (20:4) acid.