Industrial reproduction of plant-feeding fishes in Moldova without injections of the hypophysis

Materials of this site with last changes, additions and new materials are made out in 5 articles which are published in April, 2005 in the collected articles of an anniversary international scientific-practical conference "VNIIRs". (" Aquiculture and integrated technologies: problems and opportunities", vol. 2, Moscow, 2005). Here these materials are given for express-acquaintance of the experts-fish-breeders. To reserve collections of a conference "VNIIRs" it is possible on e-mail: LfB@flexuser.ru.
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INDUSTRIAL REPRODUCTION OF PLANT-FEEDING FISHES IN MOLDOVA WITHOUT INJECTIONS OF THE HYPOPHYSIS

Arikov P.D., Jitaru I.A.

In increase fish-productivity of ponds, reservoirs of complex purpose and farms the important role is allocated to bioengineering of breeding and rearing Far East plant-feeding fishes, silver carps and a cupid. Moldova (IV-VI zones of fish culture) in the climatic attitude is favorable region for introduction and cultivation of these fishes. Use plant-feeding fishes in polyculture allows to utilize a significant part of the primary fodder production formed in reservoirs, and to create advantageous in the aesthetic attitude ecological system. It became very necessary in connection with sharp decrease in manufacture of the carp, traditional object of fish culture, because of chronic shortage of mixed fodders and hormonal preparations stimulating spawning. The volume of the commodity fish who have been brought up in state fish farms, joint-stock fish-industrial societies, farmer fish-breeding facilities of Moldova has reached of 3000 tons on which share it is necessary 70-80% of plant-feeding fishes last years.

The basic limiting factor constraining wide industrial assimilation of plant-feeding fishes in Moldova, lack of a fish-landing material is. Maintenance of fish facilities with enough of a fish-landing material in many respects depends on presence breeding repair-mothering herds of plant-feeding fishes, reproduction complexes and stimulating ovulation and spermiation preparations. The hypophysis of fishes is not made in enough in Moldova, and delivered from Russia, Ukraine and other countries that manages to facilities very dearly. For hormonal stimulation of manufacturers plant-feeding fishes per 1999-2004 in SIFFS experimental preparation Nerestin which main principle of action consists in stimulation of synthesis and allocation by a hypophysis own gonadotropines at physiologically prepared fishes has been transferred for research-and-production tests from SPC "Aquaculture", Russia.

The mothering material has been submitted by three kinds plant-feeding fishes: a white silver carp (Hypophtalmichtis molitrix) IV generations of selection, a motley silver carp (Aristichtys nobilis) II generations of selection and a white cupid (Ctenopharygodon idella) III generations of the selection, taking place in fish-nurseries of joint-stock company “Kosteshty“ and joint-stock company “Orhei-Gura-Bykului” and received by a method of continuous cultivation with observance of all actions on breeding work. For reproduction used females a white silver carp of the Chinese line in the age of 5-6 years in average weight of 4,5-6,5 kg, 8-years a motley silver carp in average weight of 11,5-13,0 kg and 5-6-years a white cupid in average weight of 5,3-6,3 kg. Work on reception of posterity started in the third decade of May with approach of steady temperature of water 19-20⁰ С in the morning (at a level of the bottom border of a physiological optimum).

Temperature and hydrochemical modes of prespawning ponds and during spawning campaign were basically favorable. Monthly average parameters of temperature have made in April - 13,8⁰ С, in May - 18,7⁰ С, in June - 22,8⁰ С, in July - 24,3 ⁰ С. Content of the oxygen dissolved of water did not fall below 5,2 mg/liter in the morning, however рН have been shifted in the alkaline party and made 8,1 - 8,4. Parameters of a chemical compound of water of ponds of the specified facilities were within the limits of norms (table 1).

Table 1. The hydrochemical analysis of water

On all parameters of chemical compounds water was suitable for carrying out of spawning campaign, except for рН. As is known, at shift рН in the alkaline party probably increase in the maintenance in water ichthyo-and embriotoxic NH4. For downturn рН waters up to 8,1 used aluminium sulphat at the rate of 50 kg /hectare.

As the preparations stimulating maturing and allocation of sexual products of fishes in the control used suspension acetonised hypophysis of bream and a carp and, for comparison, experimental preparations Nerestin -1, Nerestin-1А and Nerestin -1B, given in gift Russian SPC “Aquaculture”. This small enterprise created in 1988, initially specialized in fish culture on replacement hypophysis injections at reproduction of plant-feeding fishes.

To reception of sexual products of plant-feeding fishes applied a method of fractional injections. For females under this scheme entered preparation Nerestin twice: the first time 20%, second time – 80% from the total doze with intervals 12 and 24 hours. At an interval of time between introductions 24 hours injections made for fishes in the evening during the period from 17.00 till 20.30. Such mode of introduction of a preparation has been set by necessity to carry out postinjectional keeping of manufacturers, reception of sexual products and a bookmark of spawn on incubation at rather stable optimum temperature mode in view of risk strong warming up waters in the afternoon day. However, under this scheme of works, the risk of evening-night recession of temperature below an optimum has not been excluded during time after injections. The average interval of time from an allowing injection before reception of spawn depending on temperature of water in experience with Nerestin made 8,0 – 9,2 hours, i.e. appeared below recommended period 10.5 – 13.0 hours. That testifies to some overdose of a preparation. For males a preparation entered once for 1 hour up to an allowing injection for females. Average the volume and quality sperm of males at use Nerestin corresponded to norms and control values at introduction of a hypophysis. The total dozes for female have made for Nerestin-1 – 0,45 ml/kg, for Nerestin-1B – 0,3 ml/kg and Nerestin-1А – 0,18 ml/kg, for males these preparations applied in volume 1/2-2/3 from the general doze given for females.

Experiments have shown, that use of Nerestin gives positive, completely comparable with hypophysis control results of stimulation of maturing of manufacturers in conditions of a temperature mode of water 21-24,5⁰ С that corresponds also to an optimum mode at use of hypophysis injections. At lower temperature of water, especially at its decrease is lower 18,0⁰ С the after of injections, the percent of maturing of females was reduced and the received spawn was more poor quality.

Incubation of spawn of plant-feeding fishes carried out in devices IVL-2 and "Amur" with keeping in them larvae. In process incubation of spawn the percent of fertilisation and percent of development of spawn was checked. Fertilisation after application Nerestin in all a wide range of conditions of experiences has made from 48,5% up to 93%, development of embryos – 45 – 80%. In total with Nerestin it is received 88,98 million larvae, including a white silver carp – 56,49 million, a motley silver carp – 16,13 million and a white cupid – 16,36 million.

It is planted on rearing: 10,5 million pieces of a white silver carp, 2,5 million pieces of a motley silver carp and 2,5 million pieces of a white cupid. The output after rearing up to average weight of 25 mg has made 54,7%. In rearing ponds has been placed on cultivation 3,6 million larvae a white silver carp, 0,8 million pieces of a motley silver carp and 0,65 million pieces of a white cupid. The output 1-years younger fishes at average weight 24,8 г has made 40,3% from planted larvae, fish-productivity has made 1493 kg / hectare.

The average data on stimulation of reproductive ability plant-feeding fishes are submitted by preparation Nerestin in table 2.

As a whole research-and-production tests of preparation Nerestin at artificial reproduction of plant-feeding fishes in Moldova have shown practically full conformity of the received sexual products and piscicultural-biological parameters to similar parameters at use in the same conditions of hypophysises carp's fishes.

Table 2. Parameters of application Nerestin for reproduction plant-feeding fishes in spawning campaigns of 1999-2004 in Moldova.

Results of works have shown, that for plant-feeding fishes of a white and motley silver carp, a white cupid in conditions of favorable temperature and hydrochemical modes effective enough replacement of hypophysis injections by Nerestin is possible. It allows to solve a problem of deficiency of hypophysises and to lower expenses for stimulation of ovulation and spermiation, reception of qualitative sexual products and fish-landing a material. Precomputations have shown, that only direct expenses for purchase Nerestin at least on 25-30% can be lower, than on a hypophysis.

INDUSTRIAL REPRODUCTION OF PLANT-FEEDING FISHES IN MOLDOVA WITHOUT INJECTIONS OF THE HYPOPHYSIS.

Arikov P.D., Jitaru I.A.

The resume.

The data for 1999-2004 on reception of qualitative sexual products, fertilisation and development of spawn, an output and are submitted to survival rate of a landing material from business larvae up to younger fishes after application of Russian preparation Nerestin-1(1А, 1B) on plant-feeding fishes Hypophtalmichtis molitrix, Arustichtys nobilis, Ctenopharygodon idella in fish facilities of republic Moldova. The received results are compared to control application of a hypophysis of fishes. On 397 females and 158 males it is shown, that in a range of optimum parameters of temperature and hydrochemistry Nerestin effectively replaces injections of suspension of a hypophysis for reception of qualitative sexual products and larvae from manufacturers of the specified fishes.