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 because of its antipyretic and antiprostaglandin properties. Therefore, the present study was designed to determine whether dietary ASA or its metabolites are transferred to the egg. A single oral dose of C-14-Carboxyl-labeled ASA administered to White Leghorn hens resulted in eggs containing approximately .02% of the administered dose. More C-14-label was 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 eggs 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 postdosing. White Leghorn breeder hens fed .100, .200, and .400% ASA for an entire (13 mo) production cycle laid eggs containing measurable amounts of salicylic acid (SA, the major metabolite of ASA) in the albumen and yolk, with no detectable levels found in eggs of hens fed 0, .025, and .050% ASA. Again, more SA was detected in the albumen than in the yolk, when expressed either on a per gram or entire egg component basis, 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 production cycle without detectable accumulation (<5 ppm) of SA in the egg yolk or albumen.