The requirements of bait for leeches in the technology of breeding leeches

Leeches, like other animals, need five kinds of nutrients for their growth and development, such as protein, fat, carbohydrates, inorganic salts and vitamins. Leech in different developmental stages and in the environment, the amount of nutrients required is not the same, if we can correctly grasp the role of various nutrients, rational use of bait, to promote the healthy growth of leeches, improve production is of great significance.

(1) Protein Protein is the main component of all organs, tissues and cells in leeches. Leech pigments, antibodies, hormones, enzymes, etc. are also composed of proteins. The tissue component of protein is amino acid, the main function is to cultivate new tissues, such as growth, development, reproduction, etc.; maintain the balance between various organisms in the body, such as excretion, etc.; regulate cells and body fluids, such as regulating the pH of body fluids, generating growth and digestive hormones, etc.; generate energy, about 16 . 7 kilojoules. Therefore, protein deficiency affects leech growth. Leeches have a high demand for protein and will use protein as the main energy substance to maintain life when hungry. The protein requirement of juvenile leeches is about 30% of the total feed. As the individual grows up, the total amount of protein required in the diet also increases gradually. The protein requirement of leeches in reproduction period is about 80%.

(2) Although fat is not much in leeches, it is widely distributed in various tissues of leeches. Especially during reproduction and hibernation, leeches rely on fat stored in adipose tissue to maintain physiological needs. Fat in the decomposition, transformation and absorption of the process of utilization, can form hormones and other endocrine glands secreted by various substances. Therefore, fat is an essential nutrient for leech growth and reproduction. Because leeches can convert carbohydrates into fat, and general food contains a certain amount of fat components, so leeches fat nutrition requirements are not difficult to meet.

(3) Carbohydrate is the general term for starch, sugar and cellulose, which is the main source of heat energy in leeches. The role of carbohydrates: one is to meet the direct needs of leech tissue cells for energy; the other is to convert them into glycogen and store them in liver and body tissues to prepare for future energy needs; the third is to convert them into fat as a reserve for larger energy.

(4) Vitamins Vitamins are essential nutrients for maintaining the normal physiological functions of leeches. They are the basic components of coenzyme or auxiliary group. Leech body such as lack of vitamins, it will lead to enzyme activity disorders, metabolic disorders and disease. Such as long-term lack of vitamin A, leech skin lesions may occur; long-term lack of vitamin E, muscle atrophy, slow crawling, weakness and other symptoms may occur; long-term lack of vitamin D, it may affect the normal metabolism of calcium and phosphorus.

(5) Inorganic salts Inorganic salts mainly include calcium, phosphorus, sodium, sulfur, chlorine, magnesium and other elements, which are indispensable nutrients for forming leech tissues and maintaining normal physiological functions, and are also important catalysts for enzyme systems. It can improve the utilization rate of water and nutrients and promote its growth and development. Lack of inorganic salts causes disease.

2. The tube culture medium of the bait and its source (1) The green juicy bait has a high moisture content, a low crude protein content, and a medium nitrogen-free extract content (Table 5-1 ), which can be used as an auxiliary bait for young leeches, and can also be used as a raw material source for natural leeches.

(II) Energy diet In energy diet, the content of nitrogen-free extract is relatively high, while the protein content is relatively low (Table 5-2 ), which is the main diet for young leeches and adult leeches before winter.

(III) Protein feed Protein feed has a high protein content, especially the crude protein content in animal feed is higher (Table 5 - 3, Table 5-4, Table 5-5 ), which is the main feed source for leeches in growth period, adult leeches and breeding period.