How to raise leeches in North China

Speaking of leeches, people may not have a particularly good impression of it, because it is a blood-sucking creature, but leeches still have many functions, and they have very good medicinal effects in some aspects, so now many people are raising leeches.

Ecological habits of leeches

1. Living habits: leeches belong to cold-blooded molluscs, which can grow and reproduce in the south and north of China. They mainly live in reservoirs, ditches, paddy fields and lakes in fresh water, especially in ponds or unpolluted rivers rich in organic matter. The suitable temperature for growth was 10-40 ℃. When the temperature was lower than 3 ℃, it entered dormant hibernation period in the soil, and the stinging activity was higher than 8 ℃ from March to April of the following year. Leeches are omnivorous animals, taking the blood or body fluids of animals as the main way of life, often using plankton, insects and molluscs in the water as the main bait, and artificial conditions with all kinds of animal viscera, cooked egg yolk, formula feed and plant residues. Freshwater snail shellfish, miscellaneous fish, earthworms and so on.

2. The reproductive habits of leeches are hermaphroditic, allogeneic, in vivo fertilization, and have both male and female reproductive organs, which are carried out in the opposite direction during mating, and there is a phenomenon of "sexual reversal" in life history and the exchange of gender roles. A leech can be both a father and a mother, playing different roles in different periods of life. About a month after mating, the female genitals secrete thin mucus, which is wrapped in egg bands, shaped like "silkworm cocoons", and is excreted out of the body and hatched in wet mud at a suitable temperature. Young leeches are hatched from the cocoons in about 16-25 days and start an independent life.

Construction of culture ponds

Leech has a strong ability to adapt, it has a wide range of temperature, hunger and drought tolerance, can live in a variety of waters. General lake farms, fishing ponds, waterlogged depressions, rice paddies, river ditches, idle land in front and back of houses can all be cultivated in ponds according to local conditions. Large-scale aquaculture should choose to avoid the wind to the sun, convenient drainage and irrigation, avoid escape to build ponds, can also choose a variety of fishing ponds or waterlogged depressions for transformation and utilization. For the convenience of management, the area of the pond is not easy to be too large, and the water depth is generally about 1 meter. There is an inlet and drain at the opposite corner of the pond, and some stones, tiles or branches are placed at the bottom of the pond for its habitat. In production, we use abandoned ditches to dig partitions to build series ponds of different sizes, each 2-3 pools as a group, digging off the common ridge of the two pools and leaving out the drainage channels, which can not only activate the water body for exchange, but also facilitate management and harvesting, and achieve good results.

Seedling source

1. Capture the natural species of leeches for self-propagation. From July to October, when leeches are active and frequent, adult leeches are captured from natural waters as leeches and put into a certain water body to preserve the species and survive the winter, and the leeches can reproduce on their own the following year. The leeches with body length above 6cm are suitable and can reproduce about three times a year. Self-propagation and self-breeding is a convenient and labor-saving way and development direction. When breeding, you can put a considerable amount of snails at one time, generally 25-30kg per mu, and control the water quality. During the incubation period, the bait was fed every 5-7 days. At the beginning, the bait was crushed and sprinkled with cooked egg yolk, and in the middle and later stages, it was fed with animal blood mixed with wheat bran, peanut shell powder or chicken and pig feed.

2. Buy seeds. To the artificial farm to choose neat size, active and powerful, flexing degree of young leeches as seedlings.

3. Release seedlings. According to different culture conditions, different seedling density can be selected, and the fine culture of small cement ponds with good conditions can put up to 1000-1500 pieces per square meter. According to experience, about 0.3-2 mu of pond culture, each pond can put 100-300 leeches at a time to reproduce on their own. Young leeches generally reach gonadal maturation in 120-150 days. In the northern region, the second generation can be propagated in the same year. The parents of leeches reproduce 2-3 times a year, and individuals lay about 300 eggs.

Bait feeding and management

1. Bait. The main types of natural bait are freshwater snails, earthworms and some insects, and large-scale culture is supplemented by various animal blood, viscera, freshwater fish, shrimp, shellfish, snails, and straw of livestock formula feed and crops. Pond culture can put a certain number of wild snails or longevity snails, generally about 0.05-0.1kg/ square meters, so that they can reproduce naturally and grow symbiotically with leeches for their feeding. The number of snails should not be too much, and if there are too many snails, they will compete for the living space with the main breeds, and the host and guest will change their potential. When feeding animal blood or bait, pay attention to interval feeding and timely removal of leftover bait, especially in hot weather, so as not to pollute and spoil the water quality and affect the growth of leeches.

2. Daily management. The diseases of leeches are very few, mainly to regulate the water quality. Although the leeches do not have strict requirements on the environment and water quality, their growth and reproduction will be affected if the water environment changes too much or becomes worse. In the process of culture, the water temperature is generally maintained between 10-40 ℃, overfertilized and polluted aquaculture water should maintain a certain amount of dissolved oxygen, dissolved oxygen in general water should be greater than 0.7mg/L, hypoxia occurs, small water bodies can be solved by artificial leaching, larger water bodies should be injected into new water or change water in time, it is very important to maintain fresh water quality in summer high temperature season.

Greenhouse overwintering

Affected by the region, the northern leech culture should establish a solar overwintering greenhouse under artificial conditions in order to break its hibernating habits, increase the breeding time and shorten the listing cycle. The solar greenhouse is generally bamboo-wood-plastic structure, the northern wall is earth-cast or brick-concrete, 0.8-1.5m thick, east-west, 30-50m long, north-south span 10-15m, the number of main columns 5-7 rows. Cover with non-dripping plastic film and rollable straw to leave doors, passageways and tuyere. In the cold snow season, snow removal and artificial warming measures should also be done. The more advanced greenhouse can be made of plastic and steel without columns, but the cost is relatively high.

Through the construction of solar greenhouse, we should pay close attention to the temperature changes inside and outside the greenhouse, increase oxygen and prevent wind, cold resistance and so on, so as to ensure the normal growth and overwintering of leeches, and prepare enough bdelloid species for the next year.

Fishing and processing

1. Fishing methods: the harvesting methods of leeches are generally as follows: (1) fixed net fishing; (2) net fishing; (3) drainage fishing; (4) mechanical fishing.

2, processing methods: (1) Lime burying method: lime mixed vermiculite, buried for about 20 minutes, drying or drying, sieving the residual powder. (2) Water scalding method: pour the newly boiled boiling water into the container where the leeches are centrally placed, cover and seal for 30 minutes, then wash it out and dry it. (3) Alkali burning method: stir the leeches with edible alkali powder, or rub them with hands to make them shrink to death, rinse with water and then dry. (4) tanning method: cross the leeches with thin iron wire and dry them in the sun.

As a famous and excellent breeding variety, leech has the characteristics of fast growth, high yield, easy to popularize, small investment, quick effect and so on. It is suitable for breeding in all sizes and methods in urban and rural areas. In the current extreme shortage of natural leeches and the sharp increase in market demand, the development of artificial breeding is imperative, the benefit is obvious, is a rapid way for the majority of urban and rural people to get rich, and has great breeding prospects and development space.