First, broodstock breeding
The broodstock requires more than 6 instars and weighs more than 15 kg. It is stocked at a ratio of 1:1.5 for males and females, and has about 10 tails for herrings with 15-20 kg.
The bottom of the brooding fish pond is flat, with sandy loam as the best, keeping the water fresh, feeding mainly snails, clams, and quail meats, supplementing a small amount of bean cakes and malt, regularly adding new water and flushing water, and generally flushing water once a month in winter. And keep the water depth more than 2 meters. After the spring, lower the water level to increase the pool water temperature. Flush the water once a week. In the middle of April, increase the number of flushes. Rinse the water 2 to 3 days to promote gonad maturation.
In the broodstock pond, a small amount of whitefish can be used to regulate the water quality. At the same time, carnivorous fish such as black fish and California quail can be properly reared to catch the wild fish in the pond, which is conducive to broodstock cultivation and increase the efficiency of the pond.
Second, oxytocin
1, urine production time, water temperature: in the middle and lower reaches of the Yangtze River, urine production time is in mid-and late May, the urine production water temperature 25 to 28 main and most suitable.
2, broodstock sorting: the maturity of broodstock directly affect the oxytocin effect, the identification criteria for the male squeezing abdomen with semen out of the abdomen, immediately dispersed after encountering water, female abdomen expansion, soft elastic, abdominal sparse scales. In order to improve the maturity of the population, the network can be checked in mid-April. For poor maturity, according to individual size and maturity, according to individual size and maturity, LRH-A3 ~ 5 micrograms/tail were injected.
3, injecting oxytocic agents: commonly used oxytocculants LRH-A, DOM, PG, etc., usually two kinds of mixed with better results, my field using three-needle injection, high yield, up to 95%. LRH-A 1 microgram per kilogram of broodstock at the end of the first shot, needle distance 20 hours; LRH-A 5 micrograms per kilogram of broodstock at the end of the second shot, needle distance 8 hours; LTH-A 20 micrograms per kilogram of the third needle female fish injected Plus PG3 ~ 4 mg or add DOM4 ~ 5 mg, the dose of male and female fish as the case of injection of female parent fish dose of 1/3 ~ 1/2, injections are used intrapleural injection.
Third, heat and artificial insemination
The length of the effect varies with the temperature of the water. It has been observed that when the water temperature is 26 to 28 degrees, the effect time is 6 to 7 hours. Bring broodstock to the scheduled time and combine actual estrus conditions to capture the broodstock for artificial insemination. When inseminating, pay attention to light and rapid movement. When mixing eggs and sperm, add 0.6% normal saline, extend insemination time, and insemination. Avoid direct sunlight and splashing of rain, increase the fertilization rate, and the normal fertilization rate is over 90%.
IV. Incubation
After the water-absorbed fertilized eggs are hatched in a hatchery ring or hatching tank, the flow rate of water is such that the fertilized eggs can be washed and rolled, and the hatching water should be separated into rows, and it should not be recycled. After the fish fry come out of the membrane, the water flow should be appropriately increased to prevent the seedlings from sinking and suffocating. After 24 hours of hatching, the water flow should be appropriately reduced to avoid excessive water consumption and the consumption of fish seedlings. In the same development period, the flow rate of water is less than the nighttime in the daytime. If the weather is abnormal and the temperature difference is large, it should be appropriately reduced to avoid excessive consumption of fish seedlings. The flow rate of water in the same development period is less than that during the day. If the weather is abnormal, the water flow should be increased when the temperature difference is large.
V. Disease Prevention
Before each batch of hatching, the hatching pond should be completely cleaned of dirt, with a certain concentration of mildew net solution to disinfect, so as to prevent the main, prevent the emphasis on governance, before the fish out of the membrane, the water quality is regularly disinfected with mildew net to prevent water mildew disease. After the fish film is out of the membrane, it is easy to stain trichodinosis, which often causes a large number of deaths. A pathogen of trichodermae was found. The hatching water was immediately sputtered with 0.7 g/m3 copper sulfate and ferrous sulfate mixture until the pests were completely killed.
Six, pay close attention to daily management, improve the emergence rate
Establish and improve production and technology management systems, and strengthen administrative supervision and technical guidance. Do all aspects of the production process is responsible for, according to the guidance of technical personnel to carry out drug disinfection, skilled adjustment of water flow operation, wash, and check whether there is no escape, leakage seedlings, the normal emergence rate of more than 75%.
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