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.

Changes in plasma concentrations of reproductive steroids in female Japanese quail (Coturnix coturnix japonica) raised on long or short photoperiods

Plasma concentrations of progesterone, testosterone, estradiol, and estrone were measured by radioimmunoassay in female Japanese quail 22 to 70 days of age. The birds were raised on long (16 hr light per day) or short (8 hr light per day) photoperiods. Only the birds raised on the long photoperiod layed eggs, starting between 42 and 49 days of age. The concentration of each reproductive steroid increased between 28 and 35 days of age, but the increases were more substantial in the birds raised on long days than in the birds raised on short days. Changes in plasma progesterone and testosterone concentrations showed similar trends: the concentrations increased before the onset of lay and were maintained at a high level in the laying birds. In contrast, plasma concentrations of estradiol and estrone increased to a peak at 35-42 days and declined once egg laying became established. The short-day birds also showed increased plasma estrogen levels, maximal at 35-42 days, with estrone being at a higher concentration than estradiol. The increases in plasma steroid levels occurred during the period of rapid growth of the ovaries and oviducts in the long-day birds, although in the short-day birds the growth of these organs was much less substantial.