Plasma concentrations of prolactin during egg laying and incubation in the ruffed grouse (Bonasa umbellus)

Abstract

The plasma concentration of prolactin was measured following experimental photostimulation, during oviposition and during incubation in plasma from ruffed grouse by heterologous double-antibody radioimmunoassay. A slight increase in plasma prolactin was noted after photo-stimulation and a much larger increase was observed as subsequent eggs were laid. When the last egg was laid, plasma prolactin was maximal. This high concentration was maintained throughout incubation and declined to basal values when incubation was terminated by removal of the eggs. In hens that failed to incubate, plasma prolactin declined after the last oviposition.Brood patch development began before the first egg was laid but was not completed until incubation was initiated. Therefore, the patch began to develop when plasma concentrations of prolactin were slightly elevated but it was not fully formed until high concentrations of prolactin were maintained for several days.