Concentrations of plasma luteinising hormone, prolactin, progesterone and androgens during the ovulatory cycle of the Turkey

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Abstract
Changes in the concentrations of plasma luteinizing hormone (LH), prolactin, androgen and progesterone were measured during the ovulatory cycle of the turkey. Single pre-ovulatory peaks of plasma LH, androgen and progesterone were observed which took 8, 8 and 12 h, respectively, to increase and return to base-line values. The concentration of plasma prolactin tended to be elevated between 6 h before and 6 h after the LH peak; the maximum values occurred after the peak. The changes in the concentrations of plasma LH and progesterone were 3- and 7-fold, respectively, while 2-fold changes were observed in the concentrations of plasma androgen and prolactin. The pre-ovulatory concentration of plasma progesterone and prolactin began to decrease 4 and 6 h, respectively, after the pre-ovulatory peak of LH. Ovulation and oviposition occurred 6-8 h and 36.10 .+-. 0.57 h (standard error of the mean) (11), respectively, after the pre-ovulatory peak of LH. In birds kept on a 14 h light/dark cycle, pre-ovulatory peaks of LH were initiated only during a 10-11 h period starting within 2 h after the onset of darkness. A comparison between these data and those from the fowl suggest that the egg is retained in the turkey''s oviduct for .apprx. 3-4 h longer than in the fowl.