INFLUENCE OF THE PRESENCE OF CHICKS ON THE ABILITY TO RESUME INCUBATION BEHAVIOR IN DOMESTIC HENS (GALLUS-DOMESTICUS)

In this study, hormonal and behavioral changes associated with nest de privation in the absence or in the presence of chicks (replaced every day or not) were investigated in incubating hens. Prolactin levels dec reased, whereas LH and E2 levels increased following nest deprivation. Surprisingly, the presence of chicks had no effect on prolactin chang es. However, the presence of chicks significantly limited increases in plasma LH and estradiol. Furthermore, this inhibitory effect was grea ter when day-old chicks were replaced every day. On the other hand, th e presence of chicks induced the emergence of specific maternal behavi or, while, surprisingly, one-third of the nest-deprived hens without c hicks continued to incubate, After a 3-day deprivation period, readine ss to renest was maintained for a percentage of hens. Thus more than 2 /3 of hens deprived of the nest for 3 days in the presence of chicks r eturned to their nests during the first day of being allowed to do so, versus less than 1/3 of hens without chicks among those that previous ly disrupted incubation behavior. Plasma prolactin concentrations of t hese renesting hens increased rapidly and reached again levels charact eristic of incubating hens. We conclude that, under our experimental c onditions, presence of chicks maintains readiness to incubate without maintaining high levels of plasma prolactin. (C) 1995 Academic Press, Inc.