Dietary influences on fatty acid metabolism in the liver of the neonatal lamb.

A ‘protected’ polyunsaturated fatty acid supplement was fed to ewes during the last 8 weeks of pregnancy. The effect of this dietary supplement on the essential fatty acid composition of the liver phospholipids and associated changes in the liver Δ9- and Δ6-desaturase activities were investigated and compared with the effects of directly dosing the newborn lambs for 8 days with an unprotected polyunsaturated oil, maize oil. The maternal dietary supplement produced significant changes in the essential fatty acid composition of the neonatal lamb liver phospholipids. Although the liver Δ6-desaturase activity in these animals was also significantly higher than in the lambs from control ewes, the Δ9-desaturase was unaffected by maternal dietary supplementation. Direct dosing of the newborn lambs with maize oil failed to produce any significant changes either in the liver phospholipid fatty acid composition or in the Δ9- and Δ6-desaturase activities. These results are discussed in terms of the dietary control of liver desaturase enzyme systems.