What are the ways of raising leeches?

Leeches, commonly known as leeches, have been recorded in the Classic of Shennong Materia Medica and have high medicinal value [1]. They grow and breed in inland freshwater waters and are traditional Chinese medical aquatic animals, and their dried products are used in traditional Chinese medicine after being soaked in traditional Chinese medicine. it has the effects of treating stroke, hypertension, clearing blood stasis, amenorrhea, falling injury and so on. In recent years, leech preparations have been found to have special effects in the prevention and treatment of cardio-cerebrovascular diseases and anti-cancer. In history, it is mainly natural fishing, due to the abuse of pesticides and chemical fertilizers in recent years, and the environmental pollution caused by the "three wastes" of industry and agriculture, the wild natural resources have decreased sharply. With the in-depth development of the medicinal value of leeches, its market demand potential is huge. Around 1995, southern China began to catch natural seedlings and raised them artificially for the first time, which was a success.

There are many ways to breed leeches. Here are some common ways to breed leeches.

I. extensive farming in the wild

Extensive culture in the field is a kind of culture method which is protected by delineating the scope of culture by making use of natural conditions. Extensive farming in the wild is not regardless of asking, but also through the release of enough provenances, appropriate bait, and finally fishing. Generally, there are reservoir culture, pond culture, marsh culture, lake culture, river culture, depression culture and rice field culture and so on. These methods have the advantages of large culture area, sufficient light, rich natural bait, small investment and large income. However, the output per unit area is low and not easy to manage, so we should always pay attention to the prevention of natural enemy damage, escape prevention and the change of water level fluctuation. The following is a brief introduction to two of these farming methods.

Marsh culture

The marshland is characterized by shallow water level, lush aquatic plants, high content of organic matter and humus in the bottom of the marsh, and rich in plankton and aquatic animals. Therefore, as long as the fence is built, leeches can be released. Regular observation should be carried out and bait should be properly replenished. When the density is too high, it is necessary to catch at the right time.

Rice fields are characterized by shallow water level, suitable water temperature and rice shade, which are suitable for the growth and reproduction of leeches from oxygen content to rich bait. Therefore, there are different kinds of leeches in most paddy fields in our country. Rice farming should choose plots with convenient drainage and irrigation, adequate water sources, soil water conservation and good fertility, surrounded by fences. In the middle of the rice field, dig one or more ponds according to the size of the plot. Generally, it is appropriate to dig a pond of 1 square meter in the middle of 100 square meters, and at the same time, between ponds and ponds, as well as protective communication ditches of about 30 cm in depth and width around the paddy fields, so that the ponds and ditches are connected. When drying, shelving or fertilizing or spraying, the leeches should be lured to the pond or protected by animal blood to prevent the leeches from being killed. Fertilization had better be changed to deep application of ball fertilizer, and pesticide spraying had better be changed to low-toxic or non-toxic pesticides.

Second, intensive intensive breeding is a scientific feeding and management mode of artificial pond construction and feeding. Generally, there are fish pond culture, farm culture, indoor culture, courtyard culture and factory constant temperature culture and so on. These breeding methods have high stocking density and relatively high capital investment, which requires fine breeding techniques. But the output per unit area is more and the economic benefit is better.

The physical properties of intensive culture 1. the light transmittance is strong and the fluctuation of the water layer is small: because the water is shallow, sunlight can be transmitted to the bottom of the pond, which is conducive to the healthy growth and development of plankton, submerged plants and benthic plants. At the same time, because the water is shallow, the upper and lower layers of the water are basically uniform, and there is only a small fluctuation under the condition of wind and temperature difference. It provides a good living environment for leeches. 2. The color of the water is uncertain, and the water temperature varies seasonally: the color of the water is often different due to the soil quality, water depth, the type of fertilization and the growth and reproduction of plankton in the water. This is because the water body of phytoplankton is green, the water body of zooplankton is yellow, the water body of humus is brown or soy sauce color, the water body is turquoise when a large number of cyanobacteria are growing, and the water body is yellowish green when Anabaena spawn for a long time. The water body is brown when the ciliates reproduce vigorously, and red when a large number of water fleas appear. In the middle of the year, the water temperature is the lowest in winter, rises gradually in spring, reaches the highest in summer, and decreases gradually in autumn. The water temperature is higher from May to September in a year, which is a suitable period for leeches to grow and reproduce under natural conditions. The average temperature of the day is generally higher than the air temperature, and the average temperature difference is lower than the air temperature. Therefore, the water temperature is relatively stable than the air temperature. The water temperature is often lower than the air temperature during the day and higher than the air temperature at night. 3. If the water body deteriorates, there is a rotten smell in the water: if it is found that the water body has a special rotten smell, it means that the water body is polluted, indicating that the organic matter at the bottom of the pool, such as leftover bait, sunken animal and plant remains, feces, etc., spoilage to produce ammonia, hydrogen sulfide and other toxic gases. At this time, you should change the water or pour the pool to clean up in time to prevent a large number of leeches from dying.

Chemical properties of intensive culture 1. PH (pH value). PH refers to the pH value of the water in the pond. It is mainly the change of the ratio of free carbon dioxide to carbonate in water. The range of change is generally between 6.5 and 9.5. The pH value changes periodically between day and night: at dawn, the pH value of water decreases with the increase of carbon dioxide content (acidity); during the day, the carbon dioxide content decreases and the pH value of water increases (alkali). Practice has proved that neutral water or weakly alkaline water is beneficial to the growth and development of leeches. 2. The amount of dissolved gas. Gases include oxygen, carbon dioxide, nitrogen, ammonia, hydrogen sulfide and methane (biogas). Generally, what is more important is the amount of oxygen and carbon dioxide in the water. When the oxygen content in the water is more than 0.7 mg / L, the leeches move normally; when the dissolved oxygen in the water is less than 0.7 mg / L, the leeches climb out of the water and into the soil or grass on the shore to breathe oxygen in the air. The contents of these two gases in the pond are closely related to the diurnal variation of water temperature. The most oxygen-containing time is in the afternoon, because the green plants in the water exuberant photosynthesis at this time, consume carbon dioxide and produce a lot of oxygen. The oxygen content in the water is the lowest at dawn, because the photosynthesis of plants basically stops at night, while animals do not stop consuming oxygen and exhaling carbon dioxide. 3. The dissolved amount of inorganic salts. Inorganic salts include nitrate, phosphate, carbonate and silicate. The dissolved amount of these salts has a direct effect on the number of plankton and other animals and plants, and on the growth and reproduction of leeches.

The composition of intensive farming organisms varies significantly in different regions and seasons. But it is generally composed of the following categories of organisms. 1. Plankton: plankton are generally tiny animals and plants invisible to the naked eye. Their activity ability is limited, and most of them move passively by the flow of water. They are the main part of pond organisms and have an important impact on the growth and development of leeches. Phytoplankton mainly include lower phytoplankton, such as cyanobacteria (Microcystis, Anabaena, etc.), green algae (Drum, Chlorella, Chlorella) in summer, and diatoms that grow vigorously in spring and autumn. Zooplankton mainly include the most primitive and lowest animals in the animal kingdom. Most of them are single-celled organisms, such as paramecium, trumpet worm, tail spinous worm and so on. 2. Aquatic plants: there are mainly the following kinds of aquatic plants.

1) floating plants, such as duckweed, Wuping, etc., float completely on the surface or in the water.

2) the leaves of floating-leaf plants float on the water surface, while the roots grow in the subsoil of the pond, such as Ling, Ruocai and so on.

3) Leaf plants are rooted in the soil, while stems and leaves stand on the surface of the water, such as Reed, lotus seed grass and so on.

3. Benthos: benthos include clams and snails in molluscs, shrimp and crabs in crustaceans, non-planktonic cladocera, flexopods, etc., as well as water maggot molting, chironomid larvae, clam python larvae and so on.

4. other animals mainly include fish, bdelloids, water snakes, soft-shelled turtles, water rats and so on.

5. Fungi and bacteria multiply in large numbers of fungi and bacteria that endanger the life of leeches in seriously polluted ponds, which have a great impact on the growth of leeches.