Utility of spent Single Comb White Leghorn hens for production of polyclonal egg yolk antibody

Egg yolks can be used for the mass production of polyclonal antibodies for general binding purposes such as detection and neutralization. The intended use of egg antibodies can be lim-ited by the value of the egg for food uses. A series of experiments were conducted to determine if spent hens could be used as a viable source of eggs for the production of egg antibodies. Experiments were designed to determine the effects of hen age and molting on egg production of an antibody to a commercially relevant soluble protein antigen (SPA). The titer, or relative concentration of antibody to SPA in the egg, was determined by enzyme-linked immunosor-bent assay. The total yield of antibody from spent hens, as compared with first-cycle hens, was estimated based on antibody titer, egg-laying frequency, and egg weight. From wk 3 to 5 after primary immunization, old hens 104 wk of age had increased egg antibody titer to SPA as com-pared with young hens 20 wk of age. Egg-laying frequency and egg size did not correlate with egg antibody titer. Molting had minimal effects on titer of egg antibody to SPA; hence, molted spent hens are viable as a source of hens for the production of egg antibody. Total egg antibody yield of a flock was positively correlated with total egg mass yield because the egg antibody titer (relative concentration) was independent of egg production. Although molted spent hen