Muskrat, commonly known as green root mink and muskrat, is a precious economic animal. At the beginning of the 20th century, Canada and the United States began to domesticate artificially. Subsequently, Eastern European countries introduced and raised them one after another, and China began to raise them from the 1940s to 1950s. During the period of 1954- 1960, wild muskrat was captured in Heilongjiang, Xinjiang and introduced to Qinghai, Guizhou, Jiangsu, Zhejiang and other provinces from abroad, and it was successful. 1979, muskrat was domesticated successfully in China, and by the middle and late 1980s, it had reached a feeding climax, spreading all over most provinces, municipalities and autonomous regions in China. After natural diffusion, artificial introduction and breeding, the number of muskrat in China is also increasing, and its distribution range is becoming wider and wider.
Muskrat is rich in plush, strong in luster and elasticity, not wet in drainage and firm in skin. Its products are beautiful, warm and of good quality, and are fur designated by the state. Muskrat meat accounts for 47%-50% of live weight, protein content is 20. 1%, and fat content is only 3.9%. It is rich in minerals and tender, so it is a promising meat food. The muskrat fragrance secreted by male rats contains main components similar to natural musk, such as muscone, normuscone and alkanone. Its effect of slowing down heart rate is more obvious than that of natural musk, and it has anti-inflammatory, anti-hypoxia, blood pressure lowering, anti-inflammatory, anti-stress and androgen effects. It is an ideal substitute for natural musk and can also be used to make high-grade perfume.
Muskrat breeding has the characteristics of low investment, low feeding cost, high economic benefit and good prospect. The scale of muskrat breeding can be large or small, which can be raised in abandoned ponds and rivers, orchards and Woods, or in courtyards, balconies or flat roofs. Muskrat is a herbivore, with wide feed sources, low feeding cost and simple feeding method. As long as we pay attention to regular feeding, cleanliness and disease prevention, we can successfully reproduce.
To raise muskrat artificially, 1 need to invest in breeding rats every year 15—20 yuan and 5— 10 yuan for young rats. Each pair of breeding rats can breed about 12 a year, and the fur income is above 240 yuan (the first-class fur circulation price in the fur market is 25-30 yuan, the second-class fur is 20-25 yuan, and the third-class fur is 10- 15 yuan). Male muskrat can extract 6-7g musk in the body during estrus (March-June 65438+1October), and the current price per gram is about 140 yuan. Since the 1990s, the international muskrat skin has shown a strong sales momentum, with an annual trading volume of about 6,543,800 pieces. At present, the average annual domestic purchase volume is only 300,000 pieces, and the export volume is about 80,000 pieces, which is in great demand at home and abroad.
(2) Biological characteristics and culture techniques
1. Classification and distribution
Muskrat is a rodent, Carnivora, Microtus subfamily, Muskrat, Muskrat species, with 14 subspecies. Originally from North America, it is widely distributed, and now it is distributed in the United States, Canada, some European countries, Japan, Mongolia and other countries and regions. The first source of muskrat in China was naturally spread from the former Soviet Union to the upper reaches of Heilongjiang before 1945. Second, from 1957, China Academy of Sciences and China Native Animal Import and Export Corporation introduced and reserved from the former Soviet Union; 1958 was introduced from the coastal border areas of the former Soviet Union and scattered in Guizhou, Hubei and Hebei (Baiyangdian). Now it is distributed in Xinjiang, Heilongjiang, Shaanxi, Guizhou, Qinghai, Jilin, Liaoning, Inner Mongolia, Shandong and other 23 provinces.
2. Morphological and variety characteristics
The muskrat is cylindrical and oval, with a body length of about 35 ~ 40 cm and a tail length of 23 ~ 25 cm, and its adult weight is about 1 ~ 1.5 kg. It is the largest in Microtus subfamily. Small and flat head, bulging eyeball, poor eyesight, short ears, developed nasal cavity and sensitive sense of smell. The type of teeth is (1.0.3)/(1.0.3) × 2-16, and the teeth change with age. Age can be distinguished according to the change of teeth.
The muskrat's neck is short and thick, and there is no obvious boundary with the chubby trunk. The trunk is bigger and the chest is bigger than other animals of the same size. Because it eats grass, gastrointestinal tract Figure 2. Muskrat has a well-developed appearance, and its abdomen is much larger than its chest. The back, waist and buttocks are plump, broad and round. Muskrat has short and flexible limbs, hard hair on the inside, four fingers on the front foot and pointed toes. It has no webbed toes and can catch food. The hind limbs are longer and stronger than the forelimbs. There are half webbed toes and bristles on the toes, which will open when entering the water and play a role in promoting swimming in the water. Muskrat's tail is very long, which can act as a "rudder" when diving and swimming.
Muskrat hair can be divided into three types: needle hair, fluff and touch hair. Needle hair is long and sparse, smooth, wear-resistant and elastic. The fluff is thin, short, dense, soft and bluish gray. The back is brownish black or chestnut yellow, and the abdomen is brownish gray or yellowish. The coat is lighter in summer and autumn and darker in winter and spring.
3. Ecology and living habits
Musk rat camp lives semi-aquatic, and likes to inhabit low-lying areas with lush aquatic plants, swamps and lakes, rivers and ponds, with shallow water, stable water and drifting rafts as the most. There are also habitats in the grass and jungle near the water source. Caves are distributed on the banks of rivers, lakes and ponds, and some of them nest on rafts in Shui Piao. The cave consists of tunnel, blind hole, granary and nest room. The tunnel is curved and multi-branched, with criss-crossing upper and lower floors and a large population, with a diameter of 10 ~ 15 cm and a tunnel length of/kloc-0 ~15 m. There are many blind roads, 2 ~ 3 granaries and 2 ~ 3 passages leading to the water area. Through these passages, you can
Muskrat loves activities, but because of its obesity, short limbs and prone body, its activity radius is limited to some extent, and its activity time, frequency and route show strong regularity. Most of them are active at dawn, dusk and night, and they are nocturnal. There is a large amount of activity in early spring and late autumn, and outdoor activities are reduced in breeding season. There is less activity in winter, but no hibernation. The activity range can reach 800-3900 m2. I like swimming. I can move freely in the water. I will stick my head out of the water for air every 1-2 minutes when diving underwater. When encountering natural enemies, you can also dive into the water for 3-5 minutes. Can swim, exercise or eat in the water for a long time.
Be vigilant, be hidden, be aggressive, and different families cannot live together. Rats are mostly grouped by blood relationship. When encountering foreign or heterogeneous invasion, fierce battles will be waged against the enemy, resulting in casualties. Sensitive hearing, a little noise will quickly return to the hole or dive for concealment. Muskrats are stupid, courageous, and not too suspicious. They can approach people or animals in disguise and are easily captured by enemies or capture tools. During the lactation period of muskrat, male rats often go in and out of caves to carry food for female rats and their offspring. In case of foreign enemies, offspring can grab their mother's nipples or lie on their mother's back to escape together.
The life span of muskrat is generally 4-5 years, and the longest is 10 year. The breeding period of domestic mice is 2-3 years for males and 4-5 years for females. General wild muskrat can be domesticated into domestic muskrat after 2-3 years' domestication. Muskrat is a small animal with limited self-defense ability, so it has many natural enemies. There are mainly tigers, leopards, wolves, foxes, minks, weasels, dogs and wild cats. In addition, large carnivorous birds of prey, such as some waterfowl, eagles and eagles, are also dangerous natural enemies of muskrats.
4. Eating habits
Muskrat is a herbivore with a wide range of feeding habits, mainly feeding on aquatic plants. They like to eat buds, buds, leaves and fruits of aquatic plants, fresh tubers and tubers, as well as terrestrial weeds, wild vegetables (including their roots), cultivated crops, vegetables and their fruits, woody plants and so on. You can also eat small animals to satisfy your hunger, such as mussels, snails, frogs and small fish. The daily intake is equivalent to 40%-50% of the body weight, that is, the average daily intake of plant feed is 250-500g, and that of seeds is 25-50g.
5. Reproductive characteristics
Muskrat is a multiparous reproductive animal in seasonal estrus. Most of them are descendants of a man and a woman, and they have strong reproductive ability. They can give birth to 2-3 babies a year in three northeastern provinces, and 4-5 babies in warmer regions, with an average of 6-9 babies. Those born in early spring can still give birth to 1 baby in autumn, so each can produce 20-30 offspring every year. Musk deer can mate in 2-3 days after delivery under the condition of good nutrition, that is, the pregnancy period of "matching blood" musk deer is 23-29 days. The offspring grow and develop rapidly, and the lactation period is 20-25 days.
6. Replication technology
(1) estrus identification
In the breeding season, the male rats are in estrus continuously and the female rats are in estrus periodically. Estrus cycle can be divided into estrus and estrus. Estrus is usually 13-20 days. During this period, the female rats' mood was relatively stable and their appetite was normal. They often refuse to follow the surrounding male rats, and the vulva is closed and dry. The vulva skin is yellow and white, and it is asexual. Estrus can be divided into prophase, duration and anaphase.
Pre-estrus: Excitement and anxiety, U-shaped mouth, loose and moist vulva, slight swelling and pink mucosa. The duration is 1-2 days.
Duration of estrus: abnormal excitement, increased barking times, loss of appetite, congestion and swelling of vulva, vulva opening, purplish red, and a large amount of mucus flowing out. This period lasts 2-4 days.
Late estrus: the state of high sexual excitement gradually tends to normal, and the appetite gradually recovers. The female mouse stopped barking and refused to climb the crotch of the male mouse. At the same time, the expansion of vulva subsided, the vaginal opening narrowed to closure, the color changed from purple to reddish, and the vaginal opening secretion decreased greatly. This period lasts about 1-2 days.
(2) Breeding
One male and many females can mate in pairs, one male and many females can reproduce in groups, one male and many females can reproduce in a single circle (cage), and one male and one female can reproduce in pairs. At present, it is best for a male and a female to live together, raise each other and mate naturally. Under the condition of artificial feeding, the combination of male and female is beneficial to reproduction. Therefore, it is necessary to master the time and method of combination. Male and female identification can be carried out with reference to figs. 7-4 and 7-5. The combination time is required to start at a young age, that is, a male and a female are artificially combined after weaning and kept in the same pen for a long time, and the combination should be made at 1-2 months before mating at the latest. Combination before wintering is more beneficial to muskrat reproduction. The effect of temporary combination in breeding period is the worst. Young muskrats should avoid close relatives and choose direct combinations with similar age and weight. Adult rats should be placed in a rectangular cage with a net in the middle, or 65,438+0 rats should be placed in each compartment of the cage, so that male and female rats can smell each other, but they can't bite. After several hours or 65,438+0, -2 days of familiarity, when the two smells are similar, they can be put together for breeding.
(3) Pregnancy and childbirth
① pregnancy identification
After mating, the female rats did not estrus again in the next sexual cycle, and showed a quiet temperament, strong appetite and shiny fur, which could be preliminarily judged as pregnancy.
② Prenatal preparation
5- 10 Before labor, the small room should be thoroughly inspected, reinforced, maintained, cleaned and grassed. Pay attention to bedding grass. Don't pad before labor, but pave it in advance to avoid adverse effects on the growth of future generations.
③ Examination and nursing of young rats.
For rats with strong motherhood and lactation, there is no need to check too much. However, in order to master the situation of the mother and offspring, or under special circumstances, appropriate inspections can be carried out. When checking, the movements should be light, not rough. Inspectors should wear special plush gloves and rub their hands with straw mats to avoid bringing odor to future generations.
(4) Substitution of offspring.
Generally, rats with less than 8 litters can breastfeed their offspring by themselves, but when there are too many litters or insufficient breast milk, they should breastfeed on their behalf. It is best to be born at about the same age and weight. This method can rub the litter or feces polluted by the surrogate mother against the offspring, and then put them at the door of the small room to make them scream. As soon as the mother listens, she can put it in a small room and don't send it out for about half an hour, so she will say that the Ming Dynasty was successful. You can also drive the mother out of the room and put the offspring among the offspring in the nest until the mother returns to the room and does not take out the surrogate offspring. It's better to keep it at night than during the day. If the feeding fails, another female rat can be replaced and released again, or human milk can be fed.