The choice of spawning broodstock

1. The broodstock fishing and transport of barracuda are good at jumping and drilling, and are not easy to catch. Therefore, when the net is pulled, it must be covered with nets or pulled up from the water surface. The lower part should be pressed tightly. The speed of the net movement should not be too high. In order to prevent broodstock from being injured, nets for catching broodstock can be made of soft cotton or vinylon threads. The mesh should be 1.5cm or more. A broodstock breeding pool, preferably 1-3 times used; multiple fishing easy to affect the oxytocin effect. When the net is set up, the personnel in the water should not be too much. Generally, 2 to 3 people can catch fish and select fish. When catching fish, lightly hold the chest, hold one's head in the head, and send water to send the cloth of the broodstock inside. The cloth clips carrying the broodstock are wider and longer than the fish. At the time of delivery, the rear part of the cloth clip should be slightly raised to prevent the fish from slipping off the back of the fish clip. It is better to bring some water inside the cloth clip. When transporting, it should be light and fast to prevent the broodstock from being injured.

2. Males and females need to identify the sex of the broodstock correctly in order to identify the proportion of females and males in the palm when using oxytocin. The secondary sexual characteristics of squid and lobster fish are not obvious, and the identification of male and female is more difficult, but sexually mature broodstock, male and female, are easier to identify. Barracuda can be generally based on the following characteristics: the female head cheeks are large, triangular, body length and body height comparison of the male is small, the abdomen expands more round, there is a certain degree of curvature, reproductive season, genital valgus, slightly larger, Peach-shaped red papillae, generally larger individuals; male cheeks oval head, body length and body height comparison of females is large, the abdomen is slender, nearly straight, vent hole is small, Cylindrical white papillae, smaller individuals.

3. The choice of mature broodstock The right choice of mature broodstock is the key to ensuring the success of oxytocin production, especially for early oxytocin production. However, at present, there is no more ideal method. Generally, it is only selected based on the shape of the fish body, combined with cultivation experience and seasons. Shape observation: Mainly identified from the size, elasticity, and softness of the broodstock. Females should choose abdominal enlargement, soft and elastic feeling, the outline of the appearance of the ovary is more obvious, slightly protruding genital pores, ovulation effect is better. If the abdomen looks full and not soft, or the abdominal enlargement is limited to the front, the posterior abdomen in front of the genital hole is flat and hard, all indicate that they are not mature enough, or the maturity is poor, and the production time may be delayed appropriately. The male can choose to have a thick milky white semen well after being squeezed.

Egg-digging observation: In addition to the observation of mature females, a special oocyte can also be used to dig eggs to observe its shape, size and color. Internal and external controls are more reliable with this method. The digger is 3.0 to 3,5mm in diameter and about 20cm in length, and can be made of bamboo, stainless steel, plastic, etc. (as shown in Figure 2-4. The top is blunt, and the surface of the egg-digging part should be smooth so as not to damage the ovary.

When using, move the digger into the genital hole accurately and slowly, then insert it diagonally to the left front or right, and reach the ovary about 4cm into one side. Take the digger a few times and pull it out to get a small amount. Eggs were placed on glass slides for visual inspection and microscopy. If the limpid fish eggs are beige or orange, full and shiny, inter-grain adhesions loose, into the water to stir the energy can be dispersed, the egg diameter of 0.72mm or more, which can be used for oxytocin broodstock. The average egg size of the carp must be greater than 0,65 mm and at least 0.60 mm. This will produce a sensitive response to pituitary hormones. Induction can be effective.

4. The ratio of male to female with regard to the proportion of male and female broodstock should be appropriately matched, and the proportion of females and males 1.5 is generally used. If the male fish is poorly matured, the ratio can be appropriately increased. After using the male fish for a period of time, it can be used again.

(v) Injection of oxytocic

1. Injectable dose The amount of oxytocin used per kilogram of fish that causes normal ovulation and ejaculation in fish. The dosage units for the various hormones are different. For example, if the pituitary gland is given in mg or mg/kg, the chorionic gonadotropin is given in mg or IU/kg, and the releasing hormone analogue is expressed in ug/kg.

Correctly grasping the type and amount of oxytocin can not only promote the smooth spawning and platooning of the broodstock, but also can promote the significant progress of gonad maturation in the short term. At present, our country has reached the * phase of female sexual squid fish, using oysters, fish pituitary, human chorionic gonadotropin and luteinizing hormone-releasing hormone analogues, or mixed injection of several hormones, can effectively promote ovarian ovulation. The effective dose is: using a single hormone for spawning barracuda: 17-30 (or 15-20 mg) of pituitary gland injected per kilogram of female fish, or 14 (or 15-20 mg) of pituitary pituitary: Pituitary pituitary 11-40; or HCG3500-8000 international units; or 1RH-A100-300ug. The use of mixed hormone oxytocin: LRH-A150ug + barracuda or salmon pituitary 10mg; LRH-A100u g + HCG5.5mg (titre 1mg) or fish or pituitary pituitary 5mg) or LRH-A400ug + HCG1000 international unit + pituitary fish 1. 5mg.

The effective dose of oxytocin-induced ovulation in squid was 200. According to the Fisheries Research Institute of Fujian Province, 200 female pituitary pituitaries were injected per end, weighing approximately 250 mg. The experience of oyster production in Taiwan in China has shown that in the reproductive season, the general female broodstock has a maturity coefficient of 11 to 12, an egg diameter of 0.6 to 0.7 mm, and uses 2.5 to 6 tails per head for pituitary and 10 to one. A mixture of 60 rabbit units of Synahorin gave a good result in terms of productivity. And pointed out that injection of 150-300mg of vitamin E is important for spawning. Hawaii Institute of Oceanography, USA, used a total dose of 49-78 IU/g of human chorionic gonadotropin injection to induce fish eduction in the pool and indicated that the pituitary gonadotropin (SG-Gi00) is The fish is a potent oxytocicant with a dose of 11.9 to 20.9 ug body weight (1 mg SG-G100 equals 2250 IU HCG).

The effective dose of oxytocin varies with the maturity of adult fish, environmental conditions, and the quality of oxytocic agents, and should be flexibly controlled according to the specific circumstances. Well-done broodstock may have a lower dose, and the broodstock with poor gonadal development may have a higher dose. In the early stage of oxyderma production, the water temperature may be lower, the dose may be higher, and the amount of pituitary may be increased. In mid-oxygenation, the water temperature is higher and the dose may be lower.

2. The number of injections and the number of injections are divided into one injection and divided injections. The latter involves injecting a predetermined dose, division of labor, or three injections into fish. At present, China uses multiple injections of mullet production. The first dose is 1/3 to 1/8 of the total dose, and the second needle is then injected into the fish. If mixed hormones are used, the first needle may not be added with HCG and the second needle may be injected together. If the male fish is mature, it can be injected once when the female fish is injected with the second needle, and the dose is half of the female fish. If the maturity is poor, it can be divided into two injections. The dose of the first needle is the same as the first needle of the female and the second needle is half of the female. In the case of two injections, the best time is 24 hours. The first injection is mostly done in the afternoon. U.S. Hawaii uses steroids (HCG) to induce oyster production. Two injections are used. The first time is for preliminary measurement. One-third of the total dose (20 IU/g body weight) is injected. After 24 hours, the second time is performed again. At higher doses (about 40 IU/g body weight), females spawn within 24 h after the second injection. Israel's "DOR" breeding research station took three injections of carp pituitary gland to achieve good results in the successful spawning of carp that was originally stored in freshwater. The method is to capture the female squid stocked in freshwater for the first injection at a dose of 1.6 pituitary/kg body weight, and then put it into a freshwater storage tank (cement tank of 1.65mx 1.25m) for raising. The second injection, the dose of pituitary 2 / kg, after 7h, the third injection, a dose of 2 / kg, and add 2 international units of lutein. After 1-2 days in the freshwater tank, the squid was transferred to a tank containing half of the seawater, and gradually replaced the water with seawater within 12-24 hours. After 17 hours, the squid started to spawn.

From a physiological point of view, gonadotropin secretion from the pituitary gland is a gradual process under natural circumstances. Fractional injection is more in line with the objective laws of fish physiology, it is conducive to the preparation of oocyte maturation, and maturation The process went smoothly and completed. Especially for broodstock that is not mature enough, multiple injections can be used to obtain better results, which can avoid the physiologic response of the broodstock too quickly, thus causing the maturation of the egg and the disorder of ovulation. At the same time, it is also possible to observe whether the female ovary has reacted after the first injection and determine whether it is fully matured.

3. Preparation of Injectable Solution The hormone pituitary or LRH analogue must be dissolved or made into suspension with water for injection (physiological saline or cold water) before it can be injected into the body with water. The amount of water for injection, usually 2ml injection per fish. Preparation of pituitary injection According to the weight of broodstock, calculate the amount of pituitary required, place the fresh or preserved pituitary in a dry mortar, grind it thoroughly, and then add a few drops of pre-calculated water for injection, and then grind it into a paste. Finally, the rest of the water for injection is added and the pituitary suspension is made by stirring thoroughly.

Hormone injections are prepared by aspirating the required water for injection using a sterile syringe, inserting the needle into the rubber stopper of the hormone bottle, injecting the water, and fully dissolving it before use. After the injection is properly prepared, inhale the syringe and record the number of each syringe and the number of the scheduled fish to avoid mistaking the injection. The injection should be used immediately.

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