Some hormones involved in the nesting behaviour of hens

Fourteen hens belonging to two breeds and with nesting experience were ovariectomized, and injected daily with oestrogen for periods of 6 weeks. Thereafter they were given progesterone and oestrogen injections daily for a week alternating with a week of oestrogen injections only; at any time during this period half were receiving progesterone and oestrogen and the remainder oestrogen only. Birds of both breeds showed nest examination and nest entry following progesterone and oestrogen treatment, but some Brown Leghorns showed these behaviour patterns under the influence of oestrogen.