Immunoglobulin Y Levels in Egg Yolk From Three Chicken Genotypes

Laying hens are very efficient producers of antibodies and provide an interesting alternative for large-scale production of specific antibodies. These antibodies also have biochemical advantages over mammalian antibodies (e.g. rabbit antibodies) that can be used to improve immunoassays where antibodies are used. The concentration of IgY in egg yolk is an important production parameter. The purpose of this study was to investigate the genetic variation of IgY levels in egg yolk. We have compared IgY concentrations in egg yolks from two lines, selected for egg production traits at the Swedish University for Agricultural Sciences (Single Comb White Leghorn and Rhode Island Red) and a cross between the two lines (SLU-1392). Single Comb White Leghorns have the highest mean concentration of yolk IgY, 2.21 mg ml^-1 compared to SLU-1392 1.95 mg ml^-1 and Rhode Island Red 1.68 mg ml^-1. The cross thus had an intermediate IgY concentration in relation two the two other lines. There were great differences between individual animals within each line. Our results indicate that it should be possible to increase yolk antibody production by using a high producing chicken line and by genetic selection within the line. We found three individuals with very low yolk IgY concentrations among the Rhode Island Red hens. Newly hatched chickens with limited amounts of IgY from the hen may be more susceptible to infections.