Effects of source and level of fat in the hen's diet on the deposition of dietary oxycarotenoids in egg yolks

Abstract

The deposition of dietary oxycarotenoids in egg yolks of 576 hens was studied in a factorial experiment where diets contained three levels (0, 2 and 4 per cent) each of animal tallow and sunflower oil. The diets were isocaloric and isonitrogenous and supplemented with 22 mg kg-' of synthetic pigment. The deposition of oxycarotenoids in egg yolks was determined by both visual and colorimetric methods. Supplementing the diet with either or both fats increased the visual score of the yolk colour compared with the unsupplemented control. The colorimetric method showed a similar increase in yolk colour with all supplements except 2 per cent sunflower oil. When the two fats were mixed, yolk colour was deeper when the level of tallow was higher than that of sunflower oil.