The first step is preparing the breeding pond. The pond is nearly square in shape, covering approximately 46 acres. It is surrounded by a 8-meter-wide embankment that is 0.6 to 0.8 meters deep, with the beach surface capable of being raised up to 1.2 meters. The bottom consists of sandy soil with minimal silt, ensuring good water quality and complete water injection and drainage systems. A small wooden boat can be placed inside for feeding, fertilizing, and managing the pond. To prevent burrowing animals such as worms, crayfish, and crabs from escaping, a dense mesh of polyethylene netting is buried into the soil. The pond is constructed to be sturdy and leak-proof, and asbestos tiles are used to prevent escape. At the start of each breeding cycle, the pond must be dredged, repaired, and thoroughly disinfected using quicklime and tea seed cake. After filtration and water filling, adequate base fertilizers are applied to cultivate natural food sources, and aquatic plants like Artemisia halodendron and Vallisneria are planted. Before and after introducing large numbers of live snails, they are allowed to reproduce naturally. Next, the selection of seedlings. For fish species, after clearing the pond, about 20 kg of different types of silver carp are stocked at a rate of 20 kg per kilogram, equivalent to 4.3 kg per acre. During the middle and later stages, as aquatic plants grow excessively, grasses are controlled, and a total of 400 kg of aquatic grasses are released, averaging 8.6 kg per mu. For green prawns, after clearing the pond, young prawns can be raised at a rate of 3-5 kg per mu. Alternatively, about 80 pounds of broodstock per kg of eggs are introduced before and after April, averaging 0.5 kg per mu. For crabs, around 90,000 "bean crabs" are reared, with 1,000 larvae per kg, resulting in approximately 1,800 per mu. Other species, such as yellow earthworms, loach, and crayfish, are naturally maintained in ponds that are cultivated year-round. Pesticides are rarely used, and no additional seedlings are typically needed, allowing these organisms to reproduce naturally. Third, the feeding process. An ecological breeding method is adopted, where fish are provided with free fertilizer (chicken manure) and natural food sources such as plankton, benthos, snails, and aquatic plants. In addition, 2,000 kg of feed including 1,500 kg of soybean cake, 1,000 kg of bran, 1,000 kg of rice bran, and small weeds are given. Feeding and fertilizing are adjusted flexibly based on weather conditions, water quality, availability of natural food, pond size, and growing season. The pond is inspected daily, both morning and evening, and oxygen is added as needed depending on water quality, weather, and floating head conditions. Normally, water is added once a week, with each addition increasing the water level by 20–30 cm. The dissolved oxygen is sufficient, the water level remains stable, and the transparency is around 35 cm, with the water quality described as “fat, live, tender, and cool.” Every hour, lime is sprinkled to adjust the pH of the pond water. Fourth, disease prevention. Throughout the culture process, fish are soaked in 3% saline for 10 minutes before stocking, while shrimp and crabs are treated with 50 mg/L potassium permanganate for 2–3 minutes. During the growing season, bait is fed every two weeks, mixing 50 kg of feed with 25 g of oxytetracycline, and it is given twice daily for three days. Additionally, baits and tools are frequently disinfected with bleach. Finally, harvesting. Yellow oysters, loach, shrimp, and crayfish are caught in cages all year round, using methods that separate large and small animals. As soon as they meet market specifications, they are sold. After the Chong Yang Festival, crabs are captured by hand in the evenings and continue to be caught in cages until the end of November. After this period, the ponds are prepared for the next cycle.

Notebook Color Doppler Ultrasound Machine

Notebook Color Doppler Ultrasound Machine,Heart Color Doppler,Ultrasound Machine For Cardiac,Color Doppler Ultrasound Machine

Mianyang United Ultrasound Electronics Co., Ltd , https://www.uniultrasonic.com