Semi-artificial seedling raising technology

Variegated maggots, commonly known as flower pods, are one of the four major shellfish in Fujian Province. In recent years, the development of polyculture in the southern shrimp ponds and seedlings in the northern sea area has promoted the research and improvement of the artificial breeding technology of the calyx. Although the north has now broken through the artificial breeding and high-yielding techniques in flower beds, the current main production of flower bud seedlings is still cultivated in the south earthen ponds, and due to market demand, the time for raising the seedlings of southern flower buds has been advanced to September. The experience of successful cultivation of bud seedlings is now described below.
1 Pond Condition The pond area is 2.67 hectares. There is an independent intake and drainage system. Both big and small tides can enter the water. The water source uses the natural tide to enter the water. It meets the second class seawater quality standard. The maximum depth of the pond is 2.0m, and the minimum depth is 1.0m, the bottom of the shrimp pond is sandy and muddy. It is equipped with 4 square-shaped single-cell algae cultivation ponds, a total of 20 square meters.
2 Preparations before nursery
2.1 Installation of gate gates Taper gates are installed at inlet gates and are generally made of polyethylene meshes with a mesh size of 1 mm.
2.2 One month before the start of seedling cultivation in Qingchi. Put the dry pool water first, rinse the bottom of the pool with a mud pump, and then sprinkle lime. After a few days of exposure, plow till the beach surface, and then sand, the thickness of about 10cm, and then sprinkle with bleach disinfection.
2.3 Cultivation of monocytic algae One week before oxytocin production, the bait culture ponds were inoculated with micro-algae and Platymonas subtilis, respectively, to expand the seed and culture, so that the food organisms reached the peak of reproduction during pro-beta production.
3 Selection and production of pro-shellfish
In September, when the temperature of the seawater fell to 25°C, the pro-occlusion gonads developed and the pro-husbands were purchased, and they were selected for production during the tidal period and the winds were 3-5. The pro-family used includes two kinds of specifications, one is a second-instar shellfish of 100 to 140 capsules/kg, and the average dosage is 375 kg/ha, which is evenly laid on a mesh sheet (the mesh sheet is fixed on the urine-producing shelf). After the oxytocin is completed, it is removed together with the mesh. The other is 350-400 capsules/kg of one-year-old shellfish, with an average amount of 750 kg/ha. They are sown evenly on the beach between the two gates until they are harvested the next year.
2 days before oxytocin, wash the pool 2 to 3 times. The method of stimulating water by using water stimulation means that when the tide rises, the floodgates are opened so that the water can naturally flow into the pool and the pro-shellfish can be discharged. If the maternal maturity is good, it can be discharged on the same day or the next day. During the production period, the emission of sperm and eggs is often checked through “look and watch”. Looking at the color of the water, when the eggs are released, the surface of the water is completely white, and at the same time there is a white foam on the surface of the water at the downwind; the smell is heard in the air at the end of the air. Take a sample of the water under a microscope and see if there are eggs in the water. Once it is found that there are sperm and egg emissions, it is necessary to immediately stop the drainage, and then gradually add water to about 0.3m.
4 planktonic larva rearing
4.1 Larval density 0.5-1.0/cm2.
4.2 After the bait has been cultured and bred to the eggs, the monocytic algae cultured in the bait culture tank are immediately discharged into the pool as supplementary bait, and 0.5-1.0 g/m3 of compound fertilizer is applied, so that these baits grow rapidly and become aquatic. Dominant species. After that, fertilize once every 3 to 5 days according to the water color.
4.3 Adding and changing water According to the developmental speed of planktonic larvae, when the water level is full (about 1.5m), the larvae have developed to the late or metamorphosis stage of the shell. In this way, water 6 to 15 cm can be properly added every day. The larvae sinking and affixing will take about 3~4 days. After the larvae are basically attached, they begin to change the water. The daily water exchange rate is 10~15cm, depending on the condition of the feed in the pool water. Before changing the water, check the tide. When the tide is not good, try not to change the water.
4.4 Routine observation and examination of the physical and chemical factors of water in the pond, the development and quantity of larvae, the number of bait creatures in the water, the situation of the predators, and the situation of gates and strainers. When the larvae begin to adhere, the cans are placed in the soil pool to allow for the inspection of the larvae's attachment and the future development of juveniles.
5 After the juveniles have been cultivated for 7 to 11 days, the larvae become juveniles, and management must be strengthened.
5.1 After the water management larvae are fully attached, the amount of water changed daily
The 10cm is gradually increased to 1/3 of the total water volume, and the water depth is always controlled at about 1.5cm. This not only supplements the natural food organisms, but also maintains the fresh water quality. It is also conducive to the reproduction of benthic algae.
5.2 During the cultivation of bait, juveniles, the demand for bait is greatly increased. Fertilizer should be applied timely according to the water color and weather conditions so that the color of the water is maintained between yellow-green and yellow-brown.
5.3 Elimination of enemy pests The long-term cultivation of juveniles has a relatively high predile- cy, and fish, crab, and moss must be regularly removed.
5.4 Observations In addition to the observations during the larval rearing period, the cans were removed every few days to observe the growth and development of the juveniles.
6 Transfer seedlings from the fertilized ovum to 1~2mm commodity seedlings will take a month. When the seedlings grow to 0.5~1cm, drain the pool water and use a scraper to take the 0.5cm thick surface sediment and put it in the mesh bag. , to the sea area to continue breeding.
7 Questions and Suggestions
7.1 Pond dredging and sand-dressing is one of the key measures for the success of nursery. In order to save time, many nursery farms do not pay attention to this and cause failure.
7.2 The abundance of palatability foods directly affects the yield of flower bud seedlings. Some nursery sites are hurriedly launched in the case of insufficient feed, and even without a dedicated bait-cultivation pool, it is difficult to purchase sufficient quantities of monomon algae as a source of basic bait. The feed is severely deficient and the yield is extremely low.

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