Patterns of lipogenesis in laying hens fed a high fat diet containing safflower oil

Lipogenesis by liver and ovarian tissue in vitro, incorporation of lipids synthesized de novo into the egg yolk in ovo, and the fatty acid composition of liver and yolk triglycerides were studied in laying hens fed a low fat control diet or 30% safflower oil diet for 3 wk. The study was conducted to determine if reduced triglyceride synthesis and the fatty acid composition of dietary fat could account for the changes in the fatty acid composition of liver and egg yolk triglyceride from safflower oil feeding. Triglyceride synthesis was reduced by safflower oil feeding. Relative distribution of labeled carbon into liver triglycerides and phospholipids was also reduced. In vivo incorporation of labeled carbon from [1-14C]acetate into egg yolk triglycerides and phospholipids closely paralleled that in liver slices, suggesting that the liver controls the pattern of lipid incorporation into yolk. The fatty acid composition of liver and yolk triglycerides was markedly altered by safflower oil feeding. The changes in fatty acid composition of yolk triglycerides could not be accounted for by the reduction in triglyceride synthesis and the fatty acid composition of safflower oil.