Artificial breeding of grouper has attracted widespread attention in recent years. Take the red grouper as an example to introduce artificial seedling technology:

First, broodstock selection and cultivation

The broodstock can be artificially propagated or caught in natural sea areas. Females choose to weigh 0.5 kg-1 kg, the abdomen is enlarged and soft; males choose to weigh more than 1.5 kilograms, and the abdomen can drain the semen. Male and female broodstock with 1:1-1:3 ratio. Grouper is a female prehybrid hermaphrodite fish, and its 6th instar was transformed into a male fish. In recent years, due to overfishing, the sex ratio of polyandroidism is less in the reproductive groups of natural sea areas, and it is cultivated under cultivation conditions. Older male individuals have long broodstock and are expensive. Therefore, the problem with broodstock selection is that it is not easy for males to get mature gonads. In order to solve the problem of male broodstock deficiency in artificial reproduction, exogenous hormone 17α-methyl testosterone can be used to induce hermaphrodite red-spotted groupers, which can be used to transform females into male broodstock with reproductive function earlier than age 3 and age 4 and 17α-. Methyltestosterone can not only inhibit yolk production, but also affect oocyte proliferation and differentiation. The 50-day bait was fed to 2nd to 4th-instar fish at a dose of about 5 mg/kg body weight (cumulative volume 241.3 mg/kg body weight), resulting in a 93.5% sperm flow rate of sexually transformed male broodstock and an insemination rate of 81.1%, normal embryonic development. In order to solve the problem of “sex change” caused by uneven bait intake due to uneven intake of male hormone baits and daily feeding and time-consuming issues, males that implant 17α-methyl testosterone into fish can also be used. Hormone implantation to induce early "sex changes" in groupers. 17α-methyl testosterone can be implanted into mature red-spotted grouper females aged 3 to 7 at one time. After 50 days and 90 days, females are converted into male fish, making the grouper “sex change”. The process is 5 years -6 years earlier. Fertilized eggs obtained by using their semen have a fertilization rate of 73% and a hatching rate of 97%. The larvae develop normally and can achieve artificial breeding purposes. Under the same treatment conditions, the "sex transition" of female senior fish is shorter than that of younger fish, and it is easier to obtain modified male fish. Therefore, in the artificial reproduction should choose the older, individual larger female for degeneration treatment, the effect is better.

In order to solve the relatively rare problem of artificially breeding neutral males, cryopreservation can also be used to preserve the semen. After 2 months of cryopreservation in liquid nitrogen tanks, the semen still has the vitality equivalent to fresh essence without affecting artificial reproduction. Effect. The effect of artificial reproduction largely depends on the maturity of the gonad gonads, so it is important to strengthen broodstock development and promote gonad development before inducing spawning. Reserve or hold grouper broodstock in the indoor concrete pool, artificially strengthen the cultivation, change the water and suck the dirt daily, the broodstock can spawn and fertilize naturally without hormone production, and can obtain high-quality fertilized eggs.

Second, oxytocin

Select a good female broodstock, use a thin plastic tube or an egg digger to insert the eggs from the egg-producing hole to a depth of about 3 cm to 5 cm, and then place the eggs on a slide. Observe their maturity under a microscope. If the eggs are easy to separate, egg Yellow, full, egg diameter of 0.3 mm -0.5 mm, plus a transparent fixative liquid after the nucleus has been biased towards the animal pole, the maturity is better. Male brooders gently press on the abdomen with a little bit of semen flowing well. Grouper semen volume is small, do not squeeze too much when checking male maturity. There are 4 types of coproducers: the mixture of salmon pituitary, human chorionic gonadotropin, luteinizing hormone releasing hormone analogues, and LRH-A+PG.

Female fish used PG 10 mg/kg body weight -12 mg/kg body weight or LRH-A 60 micrograms/kg. The above dose is generally divided into two thoracic injections, the first injection volume accounts for 2/3 of the total, and the interval between the two is about 24 hours when the water temperature is 25°C-26°C. Male broodstock is injected at half the dose of females, both at the same time as the female's second injection. Water for injection is a 0.6% sodium chloride solution. The oxytocide is dissolved or made into a suspension. The injection volume is 1 ml to 2 ml for each broodstock.

Third, artificial insemination and natural spawning fertilization

Artificial insemination of red-spotted groupers should adopt dry insemination. The broodstock can be spawned 10 to 13 hours after the second injection of the oxytocic agent, and the abdomen of the female fish is gently pressed from top to bottom, and the mature fish eggs are squeezed into the disinfected white porcelain bowl, and after repeated 5 times to 6 times The broodstock can be gently returned to the broodstock tank. Immediately thereafter, the male semen was squeezed into the egg pile of a white porcelain bowl in the same manner. Grouper semen is rare. Even if it is squeezed 5 times - 6 times, it is only 1 ml - 2 ml, but it is enough. After the last squeeze is completed, the eggs and the semen in the bowl are mixed with clean feathers soaked in sterile seawater. After about 1 minute to 2 minutes, a small amount of disinfected seawater is added. After stirring for 5 minutes, it is poured on the small sterilized ones. In the washbasin, add sterile seawater and stir gently and let stand for a while. All fertilized eggs float in the upper and middle layers of water, and dead eggs or unfertilized eggs precipitate at the bottom. Wash the fertilized eggs with sterile seawater, remove excess sperm to avoid multiple sperm fertilization, and then transfer the fertilized eggs to the incubator.

When artificial insemination, direct sunlight should be avoided to avoid killing sperm. As the grouper spawns fish spawned in batches, there are several reproductive characteristics of spawning.

If the broodstock creates environmental conditions for natural spawning and fertilization in the spawning pool, it is possible to avoid the disadvantages of over-ripening or under-ripening of eggs that often occur during artificial insemination, and also to reduce the risk of brooding, squeezing eggs, and semen. Damage from broodstock. Therefore, it is also possible to strengthen the method of culturing grouper broodstock, to promote broodstock secretion of hormones, without spawning oxytocin and natural spawning and fertilization, so as to obtain a high quality fertilized eggs, improve the survival rate of larvae, reduce the deformity rate. Natural spawning is better than artificial insemination. Suitable spawning temperature 25°C-27°C, sea water salinity 32-35, pH 7.8-8.5, spawning pond area 20m2, water depth approx 1.5m, shading screen above shading, water flow 40 l/min -50 litres/minute.

IV. Incubation

Groupers produce buoyant eggs and hatching should be done in a ring incubator or hatching tank. When hatching, the egg density was 50 eggs/liter of seawater and 100 eggs/liter of seawater, and the water velocity was such that the eggs or larvae could float. The hatchery water must be fresh and must be sterilized by sand filtration and ultraviolet light. The water temperature is maintained at about 25°C, and the salinity is 30-33, and remains stable. During the incubation process, moderate inflation is required, and if the aeration is too large or too small, it is not good, and the dissolved oxygen in the sea is maintained at 5 mg/L or more. During the incubation, remove dead eggs as much as possible to make the waterproof material worse. Red-spotted grouper and blue grouper eggs In the above conditions, fish can be hatched after 24 hours from fertilization.

Greenhouse Hydroponic System

Hydroponics is a subset of hydroculture, the method of growing plants without soil, using mineral nutrient solutions in a water solvent. Terrestrial plants may be grown with only their roots exposed to the mineral solution, or the roots may be supported by an inert medium, such as perlite or gravel. The nutrients in hydroponics can come from an array of different sources; these can include but are not limited to waste from fish waste, duck manure, or normal nutrients.

Greenhouse Hydroponic System,Greenhouse A Hydroponics,Greenhouse Flat Hydroponics,Greenhouse Vertical Hydroponics

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