Effect of different synthetic gonadotrop‐releasing hormone analogues and their combinations with an anti‐dopaminergic compound on the reproduction performance of sterlet ( Acipenser ruthenus L.)

In this study, three synthetic gonadotrop‐releasing hormones (GnRH) (azagly‐nafarelin; des‐Gly 10 ‐( d ‐Ala 6 )‐LH‐RH; and des‐Gly 10 ‐( d ‐Phe 6 )‐LH‐RH) either alone or in combination with metoclopramide were used to induce reproduction of sterlet. The GnRH analogues were applied in a single dose of 40 μg kg −1 of female and 20 μg kg −1 of male body weight. Metoclopramid was administered in a simultaneous injection of 10 and 5 mg kg −1 of body weight for females and males respectively. There were no significant differences in the ovulatory responses of females; ovulation rates varied between 57% and 80%, and at the temperature of 15.5–16.0 °C about 30–34 h were required for final maturation, when eggs of 17.3±1.3% of body weight were stripped. However, the fertilization rates of the des‐Gly 10 ‐( d ‐Phe 6 )‐LH‐RH‐treated groups were significantly lower than that in the other treatment. In males, the combination of the above peptidergic hormones with metoclopramide gave significantly better results than their single application. The results demonstrate that the final stage of gamete maturation in sterlet may be achieved by several hormonal means. The possibility of using new GnRH analogues without dopamine antagonists yields new perspectives for induced breeding of sturgeons, which have particular importance in the light of meat and roe (caviar) production for human consumption.