At present, the cultured leech is about 6 ~ 12 cm long, slightly spiral, flat and fat, with a turquoise back and five black mixed circular stripes. This variety is large in size, high in spawning rate and fast in growth, which is suitable for artificial propagation.
I. Species distribution
Leech is an ancient lower animal on the earth. According to amber fossils embedded with leeches' remains found in the Baltic Sea, leeches are at least 40 million to 5,000 years old.
Leeches belong to annelids, leeches, leeches and leeches. Leeches include four orders, namely echinoderms, leeches, leeches and leeches. The following mainly introduces leeches.
Animals of the family Bufonidae have no retractable kiss, a fixed throat and three jaws in their mouths. There is no real vascular system in the body, instead, it is the blood cavity system. The blood cavity fluid is red with grape-like tissue. The reproductive system is very complicated, usually with mating organs and embryos nourished by protein in cocoons. A complete body segment is basically developed from five rings. Aquatic or terrestrial.
Such as leeches and leeches used in bloodletting therapy, blood stasis, limb replantation and other surgical operations; In ancient India, it was widely used for bloodletting to avoid using scalpels: Bacteroides javanica, Bacteroides australis and Bacteroides mansoni.
Hosts living in warm and humid mountainous areas, waiting to pass by in the grass or bamboo forest, suck the blood of vertebrates: Haemaphysalis japonica, Haemaphysalis Tianmu and Haemaphysalis salt; Wide-bodied golden leeches are widely distributed in ponds and paddy fields in China: wide-bodied golden leeches, smooth golden leeches and slender golden leeches.
Second, ecological habits.
There are many kinds of leeches with different ecological habits. Only the oversized leeches are introduced here. Because of its more eggs and strong disease resistance, the super-large wide-body golden leech is easier to raise and grows faster than the natural leech. The oversized wide-body golden leech is extremely large, nearly twice as large as the common golden leech. The body is long and flat, slightly spindle-shaped. Adults are 80 ~ 140 mm long.
The back is usually dark black, with five yellow and black longitudinal stripes and a yellow longitudinal stripe at the lower end of the side. The abdomen is light yellow with many irregular dark green spots. The number of body rings is 107, and the reproductive zone obviously accounts for 15 rings; The male genital foramen is between 33 and 34 annular sulcus. The female genital foramen is located between the 38th and 39th annular sulcus. The front sucker is small, with a jaw in the mouth and two rows of blunt teeth plates on the jaw.
Leeches are not strict with water quality and environment. Generally, the water temperature is 15 ~ 30℃, and below 10℃, the feeding growth stops, and above 35℃, the growth of leeches and hermaphroditism and heterofertilization are affected. The peak spawning period is from mid-April to May, and each leech lays 3-5 eggs at a time. After 15 ~ 25 days, 40 young leeches hatched from each cocoon.
Third, the use of leeches.
In ancient medical books in China, it was recorded that leeches were used to treat a variety of diseases, and in the middle of>, it means "mainly expelling evil blood, blood stasis, closing the moon, breaking blood and resolving food stagnation ...". Zhang Zhongjing, a medical sage, used it to eliminate pathogenic factors and strengthen the body resistance, and treated the symptoms of "blood stasis" and "water depression", which showed its unique curative effect.
Zhang Xichun praised this medicine in the later generations: "Blood stasis does not hurt new blood, it is a good medicine, pure as water, but qi is not damaged at all, while blood stasis is invisible."
Before 1500, the Egyptians began bloodletting therapy with medical leeches. By the beginning of last century, Europeans were more superstitious that medical leeches could suck sick blood from human body, and they used medical leeches for blood-sucking treatment regardless of headache and brain fever. Later, with the development of medicine, this superstitious treatment method was gradually abandoned. However, in recent years, the new use of medical leeches in medicine has been widely concerned.
Plastic surgeons use medical leeches to eliminate congestion and reduce necrosis in the vascular occlusion area after operation, thus improving the success rate of tissue transplantation and breast formation. When medical leeches are replanted or transplanted to fingers, toes, ears and nose, using medical leeches to suck blood can make veins unobstructed and greatly improve the success rate of surgery.
This is because the salivary glands of medical leeches secrete anticoagulant hirudin and histamine-like substances that dilate blood vessels when sucking blood. 65438-0987 Leech Research Group of Institute of Aquatic Animals of China Academy of Sciences cooperated with Orthopedics Department of the Third Affiliated Hospital of Hubei Medical University. Medical leeches were first used in China to treat blood stasis after replantation of severed fingers, and several cases were successful, which was widely praised at home and abroad.
A variety of active substances contained in the saliva of medical leeches are attracting wide attention from scientists all over the world and have become a hot spot for the utilization of resource animals. From 65438 to 0984, Dr. Sawyer, an American leech expert, founded the world's first leech farm and biochemical drugs Company in Sethi, Wales, England. Hirudin and hyaluronidase produced by this company have been sold to European and American countries and Japan, and tens of thousands of live medical leeches have also been sold.
Recently, a medical leech farm was built in Charleston, USA. France and Germany have transferred the gene for synthesizing hirudin into yeast and Escherichia coli, and produced cheap hirudin through genetic engineering. It can be seen that the demand and output of hirudin are expanding.
Hirudin is a low molecular weight (7000) polypeptide composed of 65 amino acids, in which glutamine and asparagine have higher molecular weight and lower isoelectric point (3.8 ~ 4.0), and are stable for a long time at room temperature. Hirudin is the most effective natural anticoagulant known, superior to heparin, and has anticoagulant and thrombolytic effects, that is, the function of promoting blood circulation and removing blood stasis in traditional Chinese medicine. Therefore, it shows great advantages and broad prospects in the treatment of septic shock, atherosclerosis, cerebral infarction, cardiovascular diseases, hypertension, ophthalmology and many other diseases lacking antithrombin.
Four, farm construction:
Choose a place with sunny ventilation and convenient drainage to build a pond. The pond is 3m wide and 1m deep, and there is no water inlet or outlet at the opposite corner of the pond. Some branches should be placed at the bottom of the pond as its habitat. Small-scale farming can build ponds by using soil pits in front of and behind houses.
Five, breeding methods:
1. Seedling source and stocking.
Leech species can be propagated or purchased by themselves, and wide-body leech is the best. The seed release standard is robust and harmless, and the specification is 20g per contract. Because this leech lays more eggs and has a high hatching rate, it can grow and be sold in early spring in June, and can breed seeds 10 ~ 15 kg per mu. Leeches are hermaphroditic, and each leech can lay eggs and reproduce. From March to April, there are generally 1 ~ 4 eggs, and each egg can breed 60 ~ 80 young leeches. Summer is the peak of its reproduction and the best season for fishing.
2. Daily management.
Leech is full of vitality, and the cultivation is mainly to adjust feed and leech. Leeches mainly feed on the blood of snails, earthworms, fish, frogs, livestock and other animals, and the artificially fed feed should be mixed with the blood of various animals, rice, chaff and so on. Put 25 kilograms of snails into each mu of water at one time, let them breed naturally, and it is best to feed the blood of animals once a week. Leeches are not strict with water sources and can grow in sewage. However, in high-density aquaculture, the water quality should be kept clean and there should be some dissolved oxygen. In the hot season from July to August, change the water irregularly.
3. Overwintering management.
After winter, leeches stop eating and hibernate in the soil. At this time, it is best to drain the water, fish it out with a net, and choose a big and strong seedling (per mu 15kg) to put in the nursery for the winter.
4. Pay attention to protecting eggs.
From April to June, 5438+00 leech eggs are spongy, mostly in semi-humid fertile soil. Therefore, paddy fields and ponds for raising leeches should not be large and deep. Pay attention to drainage in rainy days, and the water level should not soak through the soil surface, otherwise the eggs will die easily.
5. Collection and treatment.
Summer and autumn are the best time to catch leeches. After fishing, wash it, suffocate it with lime or wine, and then dry it or bake it. Fried leeches. First, stir-fry talcum powder in a pot, add the cut leeches, stir-fry until it bulges slightly, and sieve off talcum powder.