"Protected" polyunsaturated fatty acid in the diet of the ewe and the essential fatty acid status of the neonatal lamb.

A polyunsaturated fatty acid supplement, protected from biohydrogenation in the rumen by a formaldehyde-treated protein coat, was fed to ewes during the last 8 weeks of pregnancy as a possible method of improving the poor essential fatty acid status of the newborn lambs. Significant increases were observed in the concentrations of 18:2 (n-6) in both the cholesteryl ester and phospholipid fractions of the plasma and in the phospholipid fraction of the liver of the lamb at birth. Concomitantly, there were significant increases in 20:4 (n-6) concentrations and reductions in the concentrations of 20:3 (n-9). In addition, the concentration of 18:2 (n-6) in the colostrum of the ewes was increased some eightfold thereby providing a secondary source of this essential fatty acid to the lamb. A marked decrease in erythrocyte fragility was observed in lambs whose ewes had received the "protected" polyunsaturated fatty acid diet. These findings are discussed in relation to the known metabolic roles of essential fatty acids in the animal body, with particular reference to the essential fatty acid status of the lamb at birth.