Gingival factory culture

6.1 Seed selection problems (1) The specifications are neat and the size is suitable: The seed length of 5 cm is appropriate. Practice has proved that the 3cm fry is still in an unstable stage, and there will be a lot of death after entering the pool. The 5cm fry is basically stable after entering the pool: (2) Normal body color. Need to choose the same body color, the pattern is clear. Close to wild seed, eliminate whitening or blackening individuals. (3) Shape standard. It is better to choose the length and width, oval shape. For those who are too wide or too short or deformed, do not choose: (4) lively and robust. (j) The seed production process is good. (6) The water temperature is suitable. Generally spring to move seedlings to 12-15 °C is appropriate. When moving in the autumn 15-18 °C is appropriate. Moreover, it is required that the temperature of the two places should be basically the same. 6.2 Seed transport problems (1) Bring water to grow seedlings, carefully and carefully avoid mechanical damage. (2) As far as possible, use a flexible canvas tube (do not use hard plastic barrels) as far as possible, and add a thin plastic bag inside the barrel to line it up. To reduce the collision and friction of fish body. (3) Inflate oxygen and prevent floating heads. (4) To control the temperature, the water temperature difference between A and B should not be as large as 3°C: (ice can be used to reduce the water temperature during transportation). (5) 5cm fry should not exceed 2000/m2. (6) to medicine bath. In order to prevent the death of fish fry due to mechanical damage during the harvesting and transport of seedlings, 1010-6 oxytetracycline is generally used for medicinal bathing. Or post-emergence with l00l0-6 formalin bath 1h. If you can feed 1 ~ 2d 0.310-6 oxytetracycline bait is even better. 6.3 Density of seedlings In terms of a well-designed and fully equipped circular fish pond (d=6m), the initial seedling density can be calculated as the fish load of 5kg/m2. For a fry with a body length of 5 cm (about 1 g body weight), the amount of seedlings in a single pond can be calculated as follows (maximum). The 28m2 pond discharge volume = 28m25000kg/m2/10g=14000. 6.4 Seed sorting issues Gingiva grows fish quickly and grows quickly. 5cm fry in good condition with water temperature 15°C. 1 month average body length can reach 10cm, weight l0g or so; 2 months average body length up to 15cm, weight 5cm fry can increase 30 times; 3 months average body length up to 20cm, weight increased to 85-90 Times. But in the whole population, the growth rate is fast and slow, and there is a difference of 10 to 20 times in terms of body weight. This will result in the killing of small fish by large fish, so it is necessary to perform 4 to 5 times of fry sorting before reaching 20cm. The first sorting should be carried out within 1 week of the fish entering the pool, and can be sorted according to the size or 3 grades of large, medium and small. The seedling density should still be determined as the amount of fish containing 5kg/m2 of subculture fish, so the initial seedling density can be 500/m2; when the fry grows to 10cm, the sorting density can be 60/m2. Determine; finalize seedling cultivation. Fish fry body length is generally 20 to 25cm. The amount of cultivated fish is generally determined at 15kg/m2, and the cultivated density is 20-30 pieces/m2. 6.5 water exchange problems proved. When the dissolved oxygen in the water is less than 4m1/L, the normal feeding of the gums will be affected. It is better that the dissolved oxygen in the water is not less than 5 ml/L. In the case of ideal conditions such as water supply, facilities, and management level, the 100g/tail small fish can exchange between 8 and 10 ranges of water daily. With the growth of fish, its water exchange capacity should be gradually adjusted to 15-20 ranges. In order to save fuel in the cold season, the amount of water exchange can be reduced appropriately. But it should not affect the normal feeding of fish as well. Summer high temperature water exchange capacity can reach 20 ranges as well. 6.6 Feed Supply Problems At present, the types of feed used are mainly fresh live feeds, artificial feeds, and frozen fresh fish and shrimp. Compared with these three feeds, fresh live bait is the best, because the nutrients and various trace elements of this bait are not damaged, and the nutritional value is high, just like eating under natural conditions. The frozen fish and shrimps are very different. Not only does it affect the freshness, but almost all trace nutrients are destroyed. Therefore, various vitamins and minerals must be artificially added. Live bait is difficult to meet the needs of large-scale fish farming at any time. The ideal combination of bait should be a full-price, delicious-to-road series of bait that is formulated according to the needs of the fish. In the water should have a certain buoyancy and stability. Requirements bait nutrition is complete. Its diameter is smaller than the diameter of the fish to facilitate feeding. The amount of bait is calculated based on the food intake of the fish. The food intake of fish is related to the size of the fish, water temperature, dissolved oxygen and weather conditions. Here, only a brief discussion of the amount of daily feeding of gums under normal conditions is given. In accordance with the standard food mix (fresh live bait to take 3), the empirical data of the daily feed should be 3 - 3.5 times the weight of the fish for the calculation of daily feeding amount. The daily feeding amount is generally 10 to 12% before 2cm in body length, 10 to 11% before 3cm, 9 to 10% before 4cm, 8 to 9% for 5cm, 7 to 8% for 6cm, and 5 to 7 to 10cm. ~ 7%, 10 ~ 15cm is 4-5%; 15 ~ 20cm is 3-4%; 20 ~ 25cm is 3 ~ 3.5%; 25 ~ 30cm is 3%; 30 ~ 35cm is 2.5 ~ 3%. After the gum reaches 35cm, its daily feeding amount is generally no longer a big adjustment. Here is the case for a water temperature of 15-20 °C. If the water temperature is lower than 8°C. Daily feeding amount can be controlled at 0.2-0.4%. Whether the amount of bait is reasonable or not should be based on the premise of satisfying the fish's feeding needs and try not to produce residual baits as the standard. When fish are found to be inactive and there are a large number of residual baits, first check whether the amount of bait is wrong, whether there is any problem with the quality of feed, water exchange, water temperature, dissolved oxygen, ammonia nitrogen, etc., and then observe whether the fish has developed disease. In order to timely remedy. To do it while feeding, observe as much as possible and put the bait on top of the fish head (because the two eyes of the gingiva are concentrated on the upper side of the head). The number of feedings should be adjusted with the increase of the fish body, generally 5 to 10cm for 5 times 10 to 15cm for 5 times; 15 to 20cm for 3 times; 20cm above generally early and late once.

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