RESPONSE OF LAYER BREEDERS TO DIETARY ACETYLSALICYLIC-ACID .4. EGG RESIDUE STUDIES

Acetylsalicylic acid (ASA), the active ingredient of aspirin, has been evaluated as a potential feed ingredient in laying hen rations becaus e of its antipyretic and antiprostaglandin properties. Therefore, the present study was designed to determine whether dietary ASA or its met abolites are transferred to the egg. A single oral dose of C-14-Carbox yl-labeled ASA administered to White Leghorn hens resulted in eggs con taining approximately .02% of the administered dose. More C-14-label w as found in the first egg laid than in subsequent eggs laid, and more C-14-label was detected in the albumen than in the yolk when eggs were analyzed on an entire egg component basis. The distribution of the C- 14-label changed markedly with each egg laid, as 96.5, 33.5, and 12.0% of the radioactivity was present in the albumen in the first three eg gs laid following dosing. Conversely, 3.5, 66.5, and 88.0% of the egg radioactivity was present in the yolk of the first three eggs laid pos tdosing. White Leghorn breeder hens fed .100, .200, and .400% ASA for an entire (13 mo) production cycle laid eggs containing measurable amo unts of salicylic acid (SA, the major metabolite of ASA) in the albume n and yolk, with no detectable levels found in eggs of hens fed 0, .02 5, and .050% ASA. Again, more SA was detected in the albumen than in t he yolk, when expressed either on a per gram or entire egg component b asis, from hens fed.200 and.400% ASA. Thus, it appears that ASA can be fed to hens at dietary levels of .05% or lower for an entire producti on cycle without detectable accumulation (<5 ppm) of SA in the egg yol k or albumen.