Precocious induction of maturation and ovulation in northern pike (Esox lucius)

Abstract

Summary. The efficiency of partially purified salmon gonadotropin (PPSG) and human chorionic gonadotropin (HCG), administered alone or in association with a progestagen (17a-hydroxy, 20P-dihydroprogesterone : 17!-20! P, or 17a-hydroxyprogesterone : 17a P) was investigated in submature females using the germinal vesicle in non-peripheral position as the criterium for initial oocyte stage. A dose of 0.1 mg PPSG/kg gave satisfactory ovulation (89 p. 100) and fertilization (83 p. 100) rates ; a minimum dose of 0.03 mg/kg was required to induce maturation without ovulation. The same dose of PPSG (0.03 mg/kg) combined with 17a-20(3 P (3 mg/kg) or 17 0l P (3 mg/kg) 1 day later led to full maturations and partial ovulations. 17oc-20P P (3 mg/kg) administered alone caused maturation in all animals and partial ovulation or no ovulation. In all the above cases using the combined treatment or 17a-20p P alone, fertilization rates were low (20 to 41 p. 100). HCG alone or associated with 17ot-20P P (3 mg/kg) was unable to induce ovulation. It is emphasized that treatment should be started as soon as possible after capture. Three-day captivity prior to treatment led to ovarian atresia and a significant decrease in ovulation rates.Introduction.

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“…One spontaneously ovulated female from group 3 had higher fertilization and hatching rates, however, these data were limited and not comparable to other groups. Generally, hatching and fertilization rates found in our study were higher than those reported by other authors (De Montalembert et al, 1978;Billard and Marcel, 1980;Horváth, 1983;Szabó, 2001;2003;2008).…”

“…After a single injection of GnRHa, the duration of GnRHa circulation in blood may be insufficient to stimulate the surge of LH (Crim et al, 1988;Podhorec and Kouril, 2009) that is necessary to complete final oocyte maturation and ovulation in northern pike. Other factors that can influence the progression of gametogenesis are handling stress (De Montalembert et al, 1978) and stage of gonad development (Billard and Marcel, 1980). One solution to this inadequate release profile of GnRHa could be the utilisation of GnRHa delivery systems that stimulates sustained elevation of plasma LH and therefore induces the natural progression of plasma steroid increase that is associated with FOM and ovulation .…”

“…However, De Montalembert et al, (1978) showed that non-stimulated captive females might not ovulate for various reasons: stress, photo-thermal regimes, lack of spawning substrate. The present study also verified that females kept under indoor conditions rarely ovulate.…”

The effect of pimozide/LHRHa and 17α-hydroxyprogesterone on plasma steroid levels and ovulation in the African catfish, Clarias gariepinus

“…In vivo studies have shown that 17cu, 20/3-P also induces oocyte maturation in the trout ) carp (Jalabert et al, 1979) and pike (Montalembert et al, 1978). Ovulation only occurred in these studies if the 17a, 2Op-P injections were preceded by a 'priming' injection of hypophysial homogenate.…”

Precocious induction of oocyte maturation and ovulation in rainbow trout (Salmo gairdneri) : problems when using 17 α-hydroxy-20 β-dihydroprogesterone

“…In lot 3 (2 injections of 17 a-20 p P), there is a small rise in gonadotropin beginning on day 6 and reaching 12 ng/ml on day 15. (Kirshenblat, 1952) ; northern pike (de Montalembert, Jalabert and Bry, 1978).…”