Growth cycle, habits and feeding management of leeches?

Living in paddy fields, ditches, shallow polluted ponds and other places, I like to suck human blood and animal blood, and my movements are very agile. I can swim in the waves and move inchworms. Live leeches jump in warm spring every year, and the spawning period is from June to 10. In winter, I often lurk in the wet mud on the shore, and I can't eat or move, so I have a strong viability. Habit: Leech is a cold-blooded mollusk, which can grow and breed in the north and south of China. Reservoirs, ditches, paddy fields and lakes that mainly live in fresh water are mostly ponds rich in organic matter or pollution-free rivers. The optimum temperature for growth is 10-40℃, when it is lower than 3℃ in the north, it will enter a dormant period in the soil, and it will sting when it is higher than 8℃ in March-April of the following year. Leech is an omnivorous animal, which mainly feeds on animal blood or body fluids. They often feed on plankton, insects and mollusks in water, and under artificial conditions, they feed on various animal viscera, cooked egg yolk, compound feed, plant residues, freshwater snails, miscellaneous fish and earthworms.

Growth and reproduction

Breeding habits Leech is hermaphrodite, hybridized, fertilized in vivo, and has two reproductive organs. Their mating direction is opposite, and there is a phenomenon of "gender reversal" in their life history, and there is a gender role exchange. Leeches can be both fathers and mothers, and play different roles in different stages of life. About a month after mating, the female genitals secrete thin mucus, which is surrounded by the egg belt and is cocoon-shaped. It is excreted and incubated in wet mud at a suitable temperature. After about 16-25 days, the young leech hatched from the cocoon and began to live independently.

Experience and skills

65438+ The ridge around the pond is 1.8m high and 1m deep, and the area depends on the amount of bait. Generally, there are 60 ~ 654.38+10,000 young leeches per mu of water. The pool is obliquely provided with a water inlet and a water outlet. In order to facilitate leeches to perch and lay eggs, some irregular stones or branches can be placed at the bottom of the pond, and 5 ~ 8 soil platforms 20 cm above the water level can be built in the pond, each platform is about 1 m2. The ridge of the pond should also be fortified with escape ditches and built with bricks. Groove width12cm, height 8cm. When it rains, fence it, or sprinkle some lime to prevent it from running away. 2. The source of raising and stocking leeches can be capture, purchase or self-reproduction. In the initial stage of breeding, it is generally mainly natural capture, and it can also be purchased from relevant units. There are three kinds of leeches traditionally used as medicine in China: the leeches cultivated artificially are the best. Money leech is large in size and high in yield. Money leech is commonly known as "cow leech" in rural areas. Cows often crawl on cows to suck blood, so pay attention to identification when catching cows as seeds. Leeches are hermaphroditic, and each leech can spawn and reproduce, and spawn and cocoon from late March to April (the Yangtze River basin, the same below). Egg cocoons are produced in soil, and there are generally 1 ~ 4 cocoons, and the number of young leeches per cocoon is 13 ~ 35, mostly around 20, and each leech. Young leeches appeared in large numbers in June, and grew rapidly, with an average length of more than 20 mm within one month after hatching, and were indistinguishable from adults from September to June. It is advisable to release it in early spring. It can be planted, processed and sold in early spring and October. 3. Artificial propagation technology of leeches Construction of triploid fast-growing leeches breeding pond (1): The pond area should be about 30 square meters, and a square of 5m× 5m or 6m× 6m should be built. Around the pond, a platform of 1 ~ 1.5m is set near the wall of the pond, with the water surface in the middle, the water depth is 50cm, and the platform is 2cm higher than the water surface. The soil used for the platform should be loose sand with high humus content, which is convenient for leeches to make holes. Yellow mud shall not be used, and an overflow port shall be set on the washing table to prevent rainwater from flooding the table and causing replication failure. Generally, it can be divided into two types: small-scale aquaculture ponds and large-scale aquaculture ponds: ① Small-scale aquaculture ponds are generally built with ditches, with a width of 3 meters and a depth of 1 meter, with unlimited length. A number of small ponds can also be built, with ridges 40 cm wide, and each pond has a water inlet and a water outlet. There must be a spawning platform with a width of 50- 100 cm in the middle of the pond. The platform is on a horizontal plane with the water surface, and a layer of 20 cm thick humus soil is piled on the platform. As a place where leeches lay eggs and breed. The water level is 50-60 cm. (2) The construction of large-scale aquaculture ponds generally depends on the actual geographical environment to build ponds with different specifications. If the water source is inconvenient, you can also lay a plastic film on the bottom of the pool. Appropriate amount of river mud should be put into the bottom of the pond to increase the organic matter content in the water. Planting some aquatic plants in the water can purify the water and increase the oxygen content in the water. It is best to bury a circle of nylon gauze (0.5-0.6 meters high) on the shore of the pond to prevent frogs, snakes and other natural enemies from entering the breeding pond. In order to prevent the water temperature from being too high and the light from being too strong in summer, weeping willows and other trees can be planted on the bank of the pool for shading. (2) Selection of cultivated leeches: It should be used for cultivating and breeding leeches. They should be over 2 years old and weigh about 30 grams. They are physically strong, lively and active, and they quickly shrink into a ball when they touch their hands. This leech lays a lot of eggs and has a high hatching rate. According to the land area of the platform in the pool, the amount of leeches is generally about 1.5 kg per square meter. After leeches enter the pond, the water quality should be kept thick, and there should be enough plankton and snails for them to feed on. (3) Reproduction: In the middle and lower reaches of the Yangtze River, the time for leeches to lay eggs and cocoon begins in early May and lasts until mid-June (which varies with individual differences), and mid-May is the peak of their reproduction. During cocoon formation, keep quiet and avoid walking and shaking on the shore, otherwise the cocoon-forming leeches will be frightened and run away, resulting in empty cocoons. (4) Hatching management: leeches can be collected and caught in another pond for breeding or processing after laying eggs and cocoons, and the breeding pond can also be used as an incubation pond, so that cocoons can naturally hatch in the cave, and the young leeches can be hatched about 1 1 ~ 15 days after cocoon production. The newly hatched young leech looks like an adult, with yellow cork and seven purple-gray thin longitudinal stripes on both sides of its back. With the growth of young leeches, the color between the longitudinal stripes gradually changes, forming five longitudinal stripes composed of two kinds of stripes alternately, and changing into the color stripes of adults. In the incubation stage, try to avoid walking on the platform to avoid stepping on the cocoon. The surface of the platform should be kept moist and covered with a layer of aquatic plants. In case of rainy weather, the spillway should be dredged, and the water surface should not cross the platform, keeping a gap of about 3 cm. After the cultivated leeches are fished out, young mussels and snails can be put in for the young leeches to eat. After the young leeches hatch, they mainly live on egg yolk for two or three days, and they can eat after three days. The newly hatched young leeches mainly feed on the blood and juice of mussels and snails. In a mussel, there are 10 ~ 100 young leeches. Larvae will devour the whole soft part of mussels and snails when they grow up. Young leeches grow rapidly, with an average growth of 65,438+after half a month. 4. Leech feeding technology Leech has strong vitality, easy growth and easy management. The main management is feeding and regulating water quality. Sun drying (1) feeding: Leeches mainly feed on the blood of invertebrates and mammals such as snails and earthworms. The natural feed artificially raised is mainly snails from a wide range of sources, supplemented by earthworms and insect larvae, and the artificial feed is mainly the blood of various animals. Snails can be released at one time, that is, a certain number of snails (about 25 kilograms per mu) are released in the breeding pond, so that they can reproduce naturally and eat leeches freely. In order to avoid competing with leeches for space, it is not advisable to put too many snails. Feeding animal blood once a week has a significant effect on the rapid growth of leeches. Put the blood clots of pigs, cows, sheep and other animals into the pool. Every 5 meters or so, leeches gather quickly after smelling the fishy smell, and disperse after eating. The coagulation residue must be removed in time to avoid polluting the water quality. (2) Adjusting water quality: Leeches are not strict with the environment and water quality. The water temperature should be kept below 15 ~ 30℃, and then stop eating. If it is too high, it will also affect growth, and it can grow in polluted water. However, the density of artificial culture is high, so it is best to keep the water clean and ensure a certain amount of dissolved oxygen. The water temperature is high in July and August, so it is necessary to change the water properly. (3) Overwintering management: ensure leeches to overwinter safely. After winter, when the temperature drops below 10℃, leeches stop feeding and hibernate under soil or leaves. Leeches released in early spring have generally grown into adults and can be processed and sold. When fishing, drain the water first, then fish it up with a net, and choose large and strong seeds, each mu 15 ~ 20 kg, and put them in the breeding pool for the winter. It can drain water for winter. After drainage, straw or wooden poles can be covered on the pool surface to prevent freezing and keep the soil moist. You can also bring ice for the winter, and the pool water should be properly deepened to prevent complete freezing.

Feeding and management

1, feeding. The natural bait species are mainly freshwater snails, earthworms and some insects, and various animal blood, viscera, freshwater fish, shrimp, shellfish, compound feed for livestock and crop straws are added in large-scale culture. A certain number of wild snails or Amphibia canaliculata can be put into pond culture, and the number is generally about 0.05-0. 1kg/ m2, which is beneficial to their natural reproduction and growth and feeds on leeches. Don't release too many snails. If there are too many, they will compete with the main varieties for living space, and the subject and object will change hands. When feeding animal blood or mixed bait, we should pay attention to feeding at intervals and remove the remaining bait in time, especially in hot weather, so as not to pollute and destroy the water quality and affect the growth of leeches. 2. Daily management. There are few diseases of leeches, mainly regulating water quality. Although leeches are not strict with the environment and water quality, the water environment changes too much or gets worse, which affects their growth and reproduction. In the process of aquaculture, the water temperature is generally kept between 10-40℃, and the over-fertilized and polluted aquaculture water should keep a certain amount of dissolved oxygen. Generally, the dissolved oxygen in water should be greater than 0.7mg/L, resulting in anoxia. Small water bodies can be solved by artificial watering, and large water bodies should be injected with new water or changed in time. In summer and hot season, it is very important to maintain the quality of fresh water. Overwintering in hydroponic greenhouse

Affected by the region, the cultivation of leeches in northern China should establish a sunlight overwintering greenhouse under artificial conditions to break their overwintering habits, increase the cultivation time and shorten the market cycle. Generally, the solar greenhouse is of bamboo and wood structure. The north wall is made of soil or brick, with a thickness of 0.8- 1.5m, an east-west direction and a length of 30-50m, with a north-south span of10-0/5m and 5-7 rows of main columns. Covered with non-dripping plastic film and coiled straw mulch, leaving doors, passages and tuyeres. In the cold and snowy season, snow removal and artificial warming measures should also be taken. Advanced greenhouses can be made of plastic steel without columns, but the cost is relatively high. Through the construction of solar greenhouses, we will focus on the big and the small in a planned way and concentrate on wintering. In daily management, we should pay close attention to the temperature changes inside and outside the greenhouse, as well as the ability of oxygen, wind and cold resistance to ensure the normal growth and overwintering of leeches and prepare enough leeches for the coming year.

Prevention and control of leech disease

1, dry disease: due to the high temperature, the sick leech has poor appetite, little or no movement, emaciation and weakness, which is manifested as shriveled, dehydrated, shriveled and black all over. Control method: (1) Soak the sick leech in 1% salt water twice a day, each time 10 minute. ⑵ Feed yeast tablets or oxytetracycline to increase calcium-containing food and improve disease resistance. (3) Increase the water flow and lower the water temperature. 2. White spot disease: caused by more protozoa than melons. The diseased leech has white spots and small white patches on its body surface, which makes it inflexible, unbalanced and anorexia when swimming. Control method: (1) Wash the sick leech with 2 mg/L mercury nitrate for 30 minutes each time, twice a day. ⑵ Disinfect the pool water regularly with bleaching powder, usually 1-2 times a month. 3, gastroenteritis: caused by eating spoiled food or indigestible food. The sick leech has poor appetite, is lazy and has red and swollen anus. Control method: (1) Mix 0.4% sulfadiazine with bait and feed it. ⑵ Feed 0.2% oxytetracycline.

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