Chinese sturgeons live in rivers, lakes, ponds, reservoirs and other fresh waters where the water flow is gentle and fish and shrimp grow. They often appear in big mountain streams, eat fish, shrimp, insects, etc., and also eat plant foods such as aquatic plants and cereals, and special Addiction to rotten fish, rotten shrimp and other rot, hunger-resistant, but bulimia and cruel, such as the lack of food will eat each other. Chinese sturgeons mate in water from April to May. They wait for spawning after 20 days and spawn eggs several times until the end of August. Usually only 4 to 6 eggs are spawned for the first time. In the breeding season, eggs are usually spawned 3 to 4 times. Females 5 years old or older can produce 50 to 100 eggs each year. Since the 1980s, the domestic aquaculture industry has developed rapidly and has formed a certain scale of breeding. At the same time, it has brought serious diseases and has affected the sustainable development of aquaculture. Here's how to improve the resistance of Chinese sturgeon.
First, cultivate good varieties
Breeding varieties with strong disease resistance can be done by artificial hybridization or seed selection, or by cell engineering or genetic engineering techniques. However, these tasks have certain difficulties. In order to improve the disease resistance of alfalfa germplasm, the breeding industry can work hard from the following aspects at this stage:
1. Equipped with the appropriate wild cockroaches as a parent.
2. Pro-gaze should be physically robust, complete shape, normal color, smooth skin, skirt, hypertrophy, firmness, no wrinkles on the back edge of the dorsal carapace, strong resistance to disease; if found injuries, illnesses, deformities, deformities, should be Clear, can not be used as a pro-sister.
3. Avoid inbreeding and improve herd genetic quality.
4. Do not breed as much as possible with old age.
Second, strengthen feeding and management
The purpose of feeding and management is to create a good environment and nutritional conditions suitable for the growth of quail, to cultivate sturdy fleas and obtain the highest economic benefits. Undoubtedly, the strength of cricket disease resistance is closely related to the quality of feeding and management. The breeding and management technologies that enhance the disease resistance of alfalfa are:
1. As far as possible, cultivate cubs, cubs, and breeders on the spot. This measure can guarantee its type, specification, quantity and quality, and it can also avoid the introduction of pathogens when introduced from outside the country, or the introduction of injured tendons, resulting in secondary infections of pathogens.
2. Reasonable stocking. First, the density must be reasonable. A reasonable stocking density will not only reduce the breeding efficiency, but will also ease the conflicts between individuals competing for space, competing for oxygen and striving for feed, slowing down the speed of water pollution, and enhancing the constitution of the cockroach, which in turn will increase economic efficiency. The second is to classify the pools according to different specifications and avoid the occurrence of weak meats and strong foods. Third, in the juvenile breeding stage, after breeding for a period of time, it is necessary to adjust the culture density and re-classify the size.
3. "Four Ding" feeding. The content of “Four Sets†is timed: 2 times a day, 9:00 am to 10:00 pm, and 1 pm to 5 pm each time; the number of feedings is too small, the feed utilization rate is low, and one meal can not be eaten. Corruption; feeding too many times, frequent access to Dianchi, interfere with the normal life activities. Positioning: Set a fixed bait station, which is conducive to inspection of feeding conditions, timely removal of residual bait, avoid feed waste and water pollution. The bait is often fed on the feed table close to the water line, and live fresh feed can also be fed. Qualitative: Feeding fresh, non-corrupted, nutritious and palatable feed. Quantitative: The feeding amount is generally the best amount after feeding for two hours. The daily amount of dry matter for juveniles and young cubs is generally 3% to 5% of their body weight, and no more than 6% of the body weight. The amount of dry matter fed is about 1% to 1.5% of body weight, and the amount of live feed fed is about 5% to 10% or more of body weight.
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