Artificial spawning of carp (Cyprinus carpio L.); differences between the effects of reproduction in females of Hungarian, Polish and French origin treated with carp pituitary homogenate or [D-Tle6, ProNHEt9] GnRH (Lecirelin)

Abstract

The investigation concerned the reproduction effects in carp females of the Hungarian strain 8, Polish strain 2 and French strain F of ovulation stimulation with carp pituitary homogenate (0.3 mg kg−1 and after 12 h 2.7 mg kg−1) or [D-Tle6, ProNHEt9]GnRH (Lecirelin) with metoclopramide (15 μg kg−1 and 10 mg kg−1 respectively). The ovulation stimulators did not affect the weight of eggs (expressed in g and as the percentage of female body weight). However, in the group treated with pituitary homogenate (I) the least-square means estimated for these parameters were higher than in the group treated with Lecirelin (II). A statistically significant (P≤0.05) difference in the mean percentage of living embryos after 48-h incubation was observed between groups I and II, with the eggs obtained from females of group I being of better quality. The origin of females significantly (P≤0.05) affected the weight of eggs. The weight of eggs from females of Hungarian strain 8 was higher (P≤0.05) than the weight of eggs of the other two lines. With respect to parameters for egg quality (percentage of fertilized eggs and percentage of living embryos after 24-, 36- and 48-h incubation), no effect of the origin of females was observed. The interaction between the spawning agent and the origin of the females was not statistically significant with respect to the two parameters for the weight of the eggs. The least-square means test for the investigated interaction showed that after the application of pituitary homogenate, the weight of eggs obtained from strains 8 and F was similar (respectively 711.2 g and 665.0 g). However, after the application of Lecirelin the females of strain 8 yielded eggs of a high weight (934.3 g) and those of strain F of a very low weight (373.2 g). A statistically significant (P≤0.05) interaction between ovulation stimulator and origin of females was recorded for the percentage of living embryos after 24- and 36-h incubation. A dependence was found between the latency time and the reproduction effects.