EFFECT OF DIETARY ACETYLSALICYLIC-ACID ON EGGSHELL QUALITY

Acetylsalicylic acid (aspirin) is an inhibitor of prostaglandin synthesis. Many soft-shelled (SS) and shell-less (SL) eggs are laid prematurely. It is hypothesized that prostaglandins may be responsible for the premature expulsion of some SS or SL eggs. The objective of the present study was to determine whether aspirin would reduce the incidence of SS or SL eggs and result in a concomitant increase in hard-shelled (HS) eggs. Layer breeders in their 15th mo of production were divided into groups of high and low incidence SS or SL egg laying and fed either control or rations with .05% aspirin for 4 wk. A decrease (P < .05) in SL egg production occurred in the high incidence group of SS or SL egg layers fed aspirin as compared with controls, but there was no concomitant increase in HS eggs. The production of SS eggs was unaffected by dietary aspirin. It appeared that the aspirin-fed hens of the high incidence group of SS or SL egg layers were attempting to utilize more calcium for shell formation (fewer SL eggs) but at the expense of producing thinner shells for the HS eggs. Aspirin had no effect on the shell quality of HS eggs in the low incidence group of SS or SL egg layers. It was concluded that aspirin can reduce the production of SL eggs, but perhaps due to physiological limitations in calcium mobilization, these aged breeders were not able to convert the SL eggs to HS eggs.