C18 trans monounsaturated fatty acid in the diet of the hen and its accumulation in yolk and embryo tissue

The presence of trans unsaturated fatty acid isomers in the diet of the hen is readily translated into significant accumulations in the yolk lipid. In turn, the processes of yolk lipid assimilation ensure subsequent uptake into the yolk sac membrane and distribution to the developing embryonic tissues. In particular the trans isomers become associated with newly synthesised cholesteryl esters originating from the yolk sac membrane which are an essential component for yolk lipid transfer and uptake by the embryo. Within the liver, the accumulation of lipid, almost wholly as cholesteryl esters, leads to the trans isomer fraction becoming a major component of the tissue. Possible metabolic consequences arising from the transfer and subsequent substantial tissue accumulation of trans unsaturated components are outlined. In the light of definitive evidence from other animal species it is suggested from the present investigations that the presence of trans unsaturated isomers in the diets of breeder hens should be reduced to a minimum. Copyright © 1993 John Wiley & Sons, Ltd