The relationship between plasma concentrations of prolactin and consumption of feed and water during the reproductive cycle of the domestic turkey.

The plasma concentrations of prolactin (PRL) were measured throughout the reproductive cycle of turkey hens. Plasma PRL levels increased during egg laying from 20.1 +/- 3.9 ng/ml (means +/- SEM) at the first oviposition to 55.6 +/- 5.1 ng/ml at the last oviposition. Levels of PRL increased during incubation and were maintained between 70 and 90 ng/ml. After the poults were hatched, the concentration of PRL decreased rapidly and by 7 days after hatch, PRL levels were not significantly different from those observed before egg laying. The consumption of feed and water decreased significantly (P less than .05) during incubation to less than 10% of that observed during egg laying. The intake of feed and water increased rapidly after the poults were hatched. Hens lost 17% of their body weight during the incubation period. The concentration of D-(-)-3-hydroxybutyrate (DBHB) increased 16-fold during the incubation period and decreased rapidly after the poults were hatched. Body temperature and the concentration of glucose were significantly (P less than .05) depressed during incubation. Hematocrit increased significantly (P less than .05) during the transition from egg laying to incubation. These data suggest that the changes in the concentration of PRL may be related to the large changes in intermediary and water metabolism that occur during broodiness.