Endocrinological and behavioural effects of p-chlorophenylalanine (PCPA) oral administration to broody turkey hens (Meleagris gallopavo)

Changes in plasma levels of prolactin and LH, feed intake, water consumption, behavioural pattern and ovarian activity were recorded after oral administration of PCPA to broody turkey hens. A decrease in prolactin concentration was measured, from day 3, in 3 out of the 5 birds treated with 100 mg PCPA/kg body weight (BW) for 3 consecutive days. In these hens, broodiness was disrupted on day 6 and feeding activity subsequently increased to levels of photorefractory hens. Neither LH concentrations nor ovarian activity were affected after treatment with PCPA. Moreover, PCPA treatment was ineffective at a 50 mg/kg BW dose. These results confirm that a serotoninergic mechanism is probably involved in prolactin release and moreover suggest that prolactin is implicated in maintaining broody behaviour. However, the reductions in the plasma concentration of prolactin induced by PCPA were not sufficient to restore the hypothalamic-hypophyseal-ovarian axis to a physiological status characteristic of the laying hen. Therefore, PCPA does not appear to be a useful method of treating broodiness in commercial turkey hens.