EFFECT OF FISH OIL SUPPLEMENTATION ON THE COMPOSITION OF MOLECULAR-SPECIES OF CHOLINE AND ETHANOLAMINE GLYCEROPHOSPHOLIPIDS IN RUMINANT MUSCLE

Choline glycerophospholipids and ethanolamine glycerophospholipids of ruminant skeletal muscle contain approximately 40% and 65% plasmalogen , respectively. In the 1,2-diacyl-sn-glycero-3-phosphocholine (diacyl CPG), 16:0-18:2(n-6) and 16:0-18:1(n-9) accounted for about 50% of the total molecular species; in the 2-acyl-1(1-alkenyl)-sn-glycero-3-phos phocholine (alkenyl CPG), 16:0-18:2(n-6) was the predominant species. Fish oil supplementation resulted in a sixfold increase in the proport ion of 16:0-20:5(n-3) and a two- to threefold increase in the proporti on of 18:1-20:5(n-3) and 16:0-22:6(n-3) in the diacyl CPG, and there w as a 40% decrease in the proportion of 16:0-18:1(n-9). In the alkenyl CPG, fish oil supplementation increased the proportion of molecular sp ecies containing C20 and C22 polyenoic fatty acids from 34% to 64%; in both sheep and cattle, the proportion of 16:0-20:5(n-3) was greater t han any other molecular species. In contrast to the diacyl CPG, there was also an increase in the proportion of 18:0-20:5(n-3) in the alkeny l CPG. In the 1,2-diacyl-sn-glycero-3-phosphoethanolamine (diacyl EPG) , 18:0-20:4(n-6) represented about 30% of the molecular species and th is was reduced to less than 20% by fish oil supplementation. In the ac yl-1(1-alkenyl)-sn-glycero-3-phosphoethanolamine (alkenyl EPG), the mo lecular species containing C20 and C22 polyenoic fatty acids in the sn -2 position increased from 55% to 78% with fish oil supplementation an d 18:0-20:5(n-3) was the predominant molecular species; there were red uctions in the proportions of 16:0-18:2(n-6), and 18:0-18:2(n-6) but 1 8:0-20:4(n-6) was unchanged. Fish oil supplementation induced differen t patterns of fatty acid incorporation and substitution in the sn-2 po sition of the diacyl and alkenyl CPG and EPG of skeletal muscle in rum inants and this is indicative of selective acyl remodelling in these t wo phospholipids.