Alterations in phospholipid composition of egg yolks from laying hens fed choline and methionine-supplemented diets

A trial was conducted to assess the effects of choline and methionine supplementation of the diets of hens on phospholipid composition of egg yolk. By chemical analysis, the basal diet contained 16.6% protein, 1,041 parts per million (ppm) of choline, and .53% TSAA. The energy level was 2,899 kcal ME/kg diet, with no added fat. A rapid isocratic HPLC procedure using a Waters mu Bond-NH2 column (Waters Associates, Milford, MA) was developed to quantify phospholipid components. Analysis of egg samples at peak production (36 wk of age) showed significant (P less than .05) elevations in total phospholipids, phosphatidylcholine (PC), and the ratio of PC to phosphatidylethanolamine (PE), when choline was added at 500 or 1,000 ppm. Phosphatidylethanolamine, in contrast, showed a decline with choline supplementation. Methionine supplementation (125 to 250 ppm) also caused elevations in the total phospholipid composition of the egg yolk but had only modest effects on PC and PE. There was a significant (P less than .05) correlation between the yolk weight and total phospholipid concentration, PC, and the PC:PE ratio. There was a relationship between phospholipid content and weight of eggs when diets of laying hens were supplemented with choline.