RESPONSE OF LAYER BREEDERS TO DIETARY ACETYLSALICYLIC-ACID .2. EFFECTS ON CIRCULATING CONCENTRATIONS OF PROSTAGLANDIN-F(2-ALPHA)(1)

White Leghorn breeder hens were fed 0, .05,or .40% acetylsalicylic aci d (ASA) for either 1 wk or 1 mo. Blood samples were collected 4 h post entrance of an egg into the uterus (baseline) and at oviposition of a hard-shelled (HS) egg. Plasma samples were analyzed for prostaglandin (PG) F2alpha by radioimmunoassay. Peripheral PGF2alpha concentrations peaked upon oviposition of a HS egg in both ASA-fed hens as well as th e controls (0% ASA). The levels of dietary ASA and the duration of tim e the ASA was administered did not affect baseline or peak PGF2alpha c oncentrations. It was concluded that either the timing or route of adm inistration of ASA resulted in the failure of ASA to effectively reduc e peak peripheral PGF2alpha concentrations.