To stimulate spawning state of fish breeding enterprises in Ukraine traditionally use drug pituitary water suspension containing ready gonadotropin hormones. However, using this drug can cause various complications from the negative reaction of fish sires on stimulation to death of injected fish.

Replacement drugs pituitary into synthetic analogues of gonadotropin-releasing hormones, which occurs during artificial reproduction of fish in the countries with developed aquaculture has objective reasons. The drug of fish pituitary even properly processed has certain drawbacks, such as: unsterile, containing ballast protein substance that causes inflammation in the body of fish- recipient, does not have a standard activity, unsustainable for long-term of storage in the form of an water suspension, contains besides gonadotropin other hormones that cause hormonal imbalance in the body of injected fish. In addition, the pituitary glands of fish are harvested in the short-term before spawning season in the spring, before spawning ban on fishing in natural waters.

One of the ways to overcome the problems that arise when using the drug of fish pituitary – transition to synthetic substitutes of the drug, which have no inherent drawbacks. Most drug substitutes of fish pituitary contain some kind of synthetic analogues lyuliberyn – gonadotropin-releasing hormone, which stimulates gonadotropin activity adenohypophysis of fish. Later gonadotropin hormones enter the bloodstream, affecting the secretion cells and cause secretion of steroid hormones and prostaglandins, which complete the process of transfer of germ cells in spawning condition – the 5th stage of maturity (fluidity eggs and sperm).

Until recently, work has been limited to the use of injections to sturgeon fish with the drug "Surfahon", which is a synthetic analogue of lyuliberyn, but for Sturgeon this drug was not effective. Later, to encourage sturgeon in the artificial reproduction multi-drug "Ovopel" (sturgeon), "Nerestyn-5" and "Nerestyn-7" have been used. However, there are no data of the experience of Hungarian drug "Ovopel" in the sturgeon farms in Ukraine, and Russian-made drug "Nerestyn" in versions 5 and 7, although used in domestic sturgeon breeding is quite expensive, and the price for it is growing every year.

The objective of the work was to investigate the effectiveness of replacing traditional drug of fish pituitary into stimulant gonadotropic function of fish sires pituitary in order to get sturgeon in terms of aquaculture.

The study was conducted in spring 2016 on the basis of educational, scientific and industrial laboratory of fish farming, aquaculture department of National University of Life and Environmental Sciences of Ukraine and on the basis of private enterprise "Scientific production agricultural enterprise "Bester". Control in the experiment with comparative evaluation of using various stimulants served drug suspension of carp pituitary. Experimental version – experimental synthetic stimulant of fish spawning state Vadilen-2 (designer of the drug – Associate Professor of Aquaculture Kovalenko V.A.). Collection and processing of experimental materials were made using conventional research methods in fish breeding.

It was set that drugs that activate the secretion of gonadotropin hormones in the pituitary of sturgeon sires are equal to the stimulatory effect of pituitary drug. It was noted that the experimental drug Vadilen-2 had positive reaction of fish on the injection drug and did not yield carp pituitary and showed mild stimulating effect on sturgeon sires. The total dose to female sturgeon at water temperature 13–15 ⁰C range was 0.9 to 1 ml/kg body weight, male from 0.6 to 0.75 ml/kg. It was noted that female sturgeon are well prepared for the incubation period, are able to give good quality eggs even with carp pituitary dose of 3 mg/kg, which was revealed during the third round of the experiment.

Further research may be directed to the effectiveness of substitution drugs of fish pituitary on synthetic drugs GnRH analogues, with the assessment of the effect of this change in terms of the material survival of breeding fish and the duration of their active reproductive age.

Key words: sturgeon, reproduction, pituitary, Vadilen-2, spawning condition, eggs, sperm, incubation.