Induction of ovulation and oviposition in female quail with luteinizing hormone, luteinizing hormone releasing hormone, or progesterone.

Regularly laying female Japanese quail were injected 12 or 18 hr before the next expected oviposition with 25 micrograms oLH, 25 micrograms luteinizing hormone releasing hormone (LHRH), or 0.05 mg progesterone, and the subsequent oviposition was recorded and ovulation determined by autopsy 9 hr after the injection. Plasma progesterone levels were measured in blood collected from a wing vein during the postinjection interval. Vehicle-injected birds served as control. All treatments resulted in premature oviposition and ovulations in 50-100% of birds when injected 12 hr before the next expected oviposition. None of the vehicle-injected birds showed any advancement in either oviposition or ovulation. Premature oviposition was generally followed by premature ovulation within 1 hr, when birds were treated 12 hr before the next expected oviposition and was preceded by a rise in plasma progesterone levels which reached values similar to those occurring during the normal preovulatory period. When birds were injected 18 hr before the next expected oviposition, the incidence of premature oviposition was very low, premature ovulation was absent, and the rise in plasma progesterone levels following treatment was substantially less than in the former group. The results suggest that oviposition and ovulation in quail may be initiated by LHRH induced LH release from the pituitary gland and that progesterone may stimulate LHRH and LH release. The timing of the ovulatory cycle may depend upon the phase of follicular maturation.