Yak breeding technique

The level and method of yak feeding and management are restricted and influenced by the ecological environment conditions, production mode, scientific and cultural level of producers, religious belief and other factors in the distribution area of yak. There are differences among different yak groups in different regions or even in the same area. Yaks in most areas only rely on natural grassland forage to obtain the nutrients needed to maintain their life, growth, development and reproduction. It is in the cold season of winter and spring, when the forage grass of natural grassland is withered and lack of forage grass, except for a small number of young yaks and female yaks which are weak and difficult to spend spring, they are not given supplementary feeding except for a small amount of hay or silage forage grass. The management of yak herds depends on the climatic season.

1. Grazing of yaks

The grazing of yaks is divided into grazing grasslands according to different seasons and then grazed in groups in most areas, while grazing in fences is carried out in a few areas.

1. Division of pastures

The climatic conditions of yak distribution area belong to alpine grassland climate, there is only the difference between cold and warm seasons, and there is no obvious difference between the four seasons. Therefore, the pasture is generally divided into summer and autumn, winter and spring, that is, summer and autumn (warm season) and winter and spring (cold season) pasture. The division is mainly based on the elevation of the pasture, the topography, the distance from the settlement and the traffic conditions. The summer and autumn pastures are selected at the top of the shady slopes far away from the settlements, with higher altitude, cool ventilation, fewer mosquitoes and gadflies, and adequate water sources, while the winter and spring pastures are selected near the settlements, with lower elevations, convenient transportation and shelter from wind and snow.

Some areas where yaks are distributed belong to alpine and narrow valleys. Although the total area of grassland available to yaks is very vast, it is divided into relatively "sporadic" grasslands by deep valleys. Often, the grasslands used by a village, group, and household are scattered on several mountain beams, and each yak herd uses only one or two of them. Therefore, some pastures are divided into four seasons: spring, summer, autumn and winter. It is just that the use of spring and autumn pastures is short and the area is small, which seems to be a transitional pasture from winter pastures to summer pastures or from summer pastures to winter pastures. In this area, mountain gullies and forest grasslands are used as winter pastures, Ridge meadows as summer pastures, and hillside areas as spring and autumn pastures.

2. Organization of yak herd

In order to manage and make rational use of pastures and improve the production performance of yaks, yaks should be grouped according to sex, age and physiological status, mixed grazing should be avoided, cattle herd should be relatively quiet, feeding and nutritional status should be relatively uniform, and grazing difficulties should be reduced. Yak herds are generally divided into:

① lactation herd, also known as cow herd. It refers to a herd of yaks that are lactating. About 100 heads in each group. For lactating yak herds, they should be allocated to the best pastures, and appropriate supplementary feeding can be made in areas where conditions permit, so that they can produce more milk and breed as soon as possible. In the lactation yak herd, there are a considerable number of female yaks who continue to milk before calving in the same year, and can be grouped separately when the number is large.

② dry dairy herd, also known as Gamba herd. The herd refers to a herd consisting of dried yaks without calves and female yaks that have reached the age of first breeding, each herd of 150 to 200.

③ calves. It refers to a herd of cattle from weaning to less than one year old. Young yaks have a lively temperament and poor gregariousness, which interfere with the mixed grazing of adult cattle. Therefore, generally separate groups, and the population is small, it is appropriate to about 50 heads.

④ young cattle herd. It refers to a herd of cattle that is over one year old and before the age of the first mating. There are 200 heads in each group. Cattle at this age already have the ability to reproduce, so except for potential bulls, bulls and cows had better be grouped separately and grazed in isolation to prevent early mating.

⑤ fattening cattle. It refers to the herd of cattle that will be eliminated at the end of autumn and will be fattened for meat. Each herd is 150 to 200 heads, and breeder bulls can also be incorporated into this group when the number of cattle is small. For this part of the yak can be grazed in the more remote pastures, so that it is quiet, less walking, quickly fat. Areas with suitable conditions can also be fed properly to speed up the fattening speed.

However, the organization and division of the above-mentioned yak groups, as well as the size of the groups are not absolute, and each region should rationally group and graze according to local conditions according to topography, grassland area, management level and the number of yaks. in order to improve the economic benefits of yak production.

3. Rational utilization of pastures.

The utilization time of pastures in summer and autumn and winter and spring mainly depends on the growth of forage grass and climate, usually for half a year. Every year at the beginning of summer (April-May), the whole group begins to graze, from winter-spring pasture to summer-autumn pasture; every year before winter (November-December), after counting the circle stock, it is transferred to winter-spring pasture. However, due to the influence of grassland area and climate, pastures in summer and autumn are often underutilized, while pastures in winter and spring are overutilized. The results show that there is a great contradiction between supply and demand of grass and livestock, and there is a seasonal imbalance, and yaks are basically semi-hungry in winter and spring. Fat loss is serious. The demand for yak milk and meat products is increasing rapidly, the market price is rising, and the price ratio between yak and sheep wool and meat is out of balance. Raising yaks has higher economic benefits and more income than other livestock; in addition, under the influence of the traditional concept that "cattle" is wealth, the number of yaks continues to grow, while the number of sheep and goats decreases. It leads to the imbalance of the proportion of yaks in the livestock structure of grassland, which makes the unreasonable proportion of cattle and sheep more unreasonable, and further expands the contradiction between grass and livestock in winter and spring, resulting in serious overloading and overgrazing. Therefore, in the actual production, we should optimize the yak population structure and control or reduce the development of yak population in order to make rational use of grassland resources and improve the quantity and economic benefits of yak milk, meat and other products.

In summer and autumn, yak herds move their grazing land every 10 to 40 days according to the growth status of forage grass and the size of cattle. The direction and route of relocation should be basically fixed, year after year. The distance between the two pastures should not exceed 20km. There are two ways to move: one is to move people, animals and tent facilities at the same time. Yak herds basically do not feed on the way, and graze after they arrive in the new pasture. The other is that people and tent facilities are relocated to new pastures, while yaks graze as usual and do not go with people and things. It's just that the direction of grazing is toward the new pasture, and gradually move closer to the new pasture, and harvest in the new pasture at night.

The interval between the relocation of pastures in winter and spring can be extended, generally in a cold season in winter and spring, the relocation is 2-5 times. If the yak herd is small and has the condition to give a certain amount of supplementary feeding, it may not be relocated in a cold season.

4. Shed ring

On the grasslands where yaks are grazed, there are generally few grazing facilities except sheds, some simple breeding racks and roadway circles for vaccination.

The yak shed is only built in winter and spring pastures and is only used by cattle at night. Most of them are based on local materials, and there are permanent, semi-permanent and temporary types.

① mud circle. The mud ring is a more permanent grazing facility, which should generally be built on settlements or on winter and spring pastures not far from the settlements. One circle per household or more than one circle per household. It is mainly used for lactating cattle and young cattle.

The mud ring wall is 1 ~ 1.2m high and 200 ~ 600m in size. on one side of the circle, scaffolding can be built by means of wood or wicker weaving and pressing clay, with the back facing the sun.

Mud circles can be built alone, or two, three or four or five circles can be connected. The circle and the circle are separated by an earthen wall or a wooden fence, and there is communication within the column. In a circle at the top, a roadway in this column can be built for vaccination, drug administration, etc.

② dung ring. It is a temporary pastoral facility made of cow dung. When the yak herd enters the pasture in the cold season of winter and spring, it begins to pile up around the pasture. The method is to accumulate a layer of 15~500px high with fresh cow dung every day. After one day and night, the cow dung is frozen and firm, and then another layer is piled up the next day, forming a circle for several days in a row. There are two kinds of dung ring: one is no top ring, such as four walls, closed adult yak, a larger area, can prevent wind and snow. The other is a yak with a top ring and a closed fence, which is shaped like an upside-down tile jar, and its foundation is like a horseshoe, with a diameter of about 1m. The pile on each layer gradually shrinks to the top, which is about 1m high, just enough to hold a calf. The opening of the circle is opposite to the main wind direction, a wooden stake is nailed outside, and the calf yak is tied to the pile, which can enter and leave the ring door freely. The circle can be covered with some hay to keep warm.

③ fur ring. It is a semi-permanent pastoral facility that can still be used in the second year after repair. In the winter and spring pastures to choose shelter to the sun, delimit the scope, the use of the turf within the range, stacked into a circle. The turf pile is about 60~2500px high for male yaks and pack cattle.

④ wooden fence. The leftover material from the log is used to form a circle, which can be covered with a ceiling and used to close the calf yak. The wooden fence circle can be built in a corner of the mud circle to form a circle in the middle of the circle, that is, a corner of the mud circle is selected and surrounded by a small wooden fence to open a low door. The enclosure is covered with bedding grass to allow the calf yak to enter and leave freely. The calf yak was closed at night, isolated from the female yak, and the female yak camped and grazed at night in order to milk the next morning.

5. Management of grazing yak herd

The temperament of yak belongs to strong and unbalanced type, showing rough, wild, timid, easy to panic, but strong gregariousness, the conditioned reflex established by training is not easy to disappear, and is better able to follow the command. Therefore, large herds of yak grazing, generally only need a herdsman, not easy to lose. According to the frightening characteristics of yaks, after the yak herd enters the grazing land, the herdsmen should not follow the yak herd closely, lest the yaks wander around and do not feed quietly. In order to prevent cattle from crossing the border and wolves attacking, herders can choose a place with a certain distance from the yak herd, which can take care of the highland of the whole herd to guard and watch.

The way to control the yak herd to follow orders is for herders to use specific calls and commands, accompanied by throwing small stones. The yaks that are separated from the group are usually thrown with small stones, which are thrown with bare hands at a distance of tens of meters. It can also be thrown with a grazing whip at a long distance. The landing of the stone, the swishing sound of it flying in the air, and the whip of the grazing whip are all warnings and signals to the yak. The yak will judge the direction in which it should go according to the location of the stone and the source of the sound. Herders use grazing whips to drive yaks forward, gather or disperse. The yaks that walk away from the herd will soon join the group when they hear the sound of whips and flying stones, as well as rockfall points.

The grazing schedule of yak herds varies according to the types and seasons of yak herds. The general principle is: "go out early in summer and autumn, come back late in winter and spring", in order to facilitate food intake, catch fat and provide products.

① grazing in summer and autumn. The main task of grazing in summer and autumn is to increase milk yield, do a good job of fattening and breeding, so that the yaks to be slaughtered will be out of the pen before winter, and other cattle will only lay a good foundation for overwintering and spring. After entering the summer and autumn, strive for the yak herd to leave the pasture in winter and spring early. When moving to the pasture in summer and autumn, the daily itinerary of the yak herd should be 10~15km, grazing while moving to the destination.

In summer and autumn, it is necessary to graze early and return to grazing late, so as to prolong the grazing time and let yaks feed more. When the weather is hot, let the yaks regurgitate and lie down in a cool place at noon. After coming out of grazing, grazing gradually from low to ventilated and cool mountains; grazing from pastures with poor forage quality or poor palatability to pastures with good forage quality; and allowing yaks to feed again on the pastures grazed the day before. At this time, the yaks are hungry because they have just come out of grazing, so they are not strict in the selection of forage grass and can eat pasture with poor palatability, which can reduce the waste of forage grass. When grazing on the pasture with good forage quality, it is necessary to control the cattle and make the yaks feed in horizontal teams to ensure that each cow can fully feed, so as to avoid waste caused by running trampling on the forage grass or uneven feeding.

Grazing in summer and autumn according to the arranged pasture or rotational grazing plan, the pasture should be changed and relocated in time, so that cow dung is evenly distributed on the pasture, and at the same time reduce the trample on the pasture, especially around the enclosure. This can improve the state of vegetation, increase forage yield and reduce the infection of parasitic diseases.

When the settlement is more than 2km from the pasture, it should be relocated so as to reduce the daily time of grazing and return to grazing and the physical exertion of yaks. The yaks with calves for lactation were relocated once in 10 days, and the pasture was changed once in 3 to 5 days. Grazing should be carried out according to the grazing plan of the pasture, instead of driving the grass or grazing the grassland, so as to avoid driving the cattle to run for good grass every day, resulting in adverse effects on the health of yaks and pastures.

② grazing in winter and spring. The main task of grazing in winter and spring is to keep fat and protect the fetus. Prevent yak from being weak, make cattle safely overwinter and spring, safely give birth to pregnant female yaks, and improve the survival rate of calves.

Grazing in winter and spring should come out late and return to grazing early, making full use of the warm noon time for grazing and drinking water. Distant slopes and shady mountains on sunny days; near grazing in windy and snowy days, depressions or bays sheltered from the wind. The grazing cattle marched downwind. Pregnant female yaks avoid grazing on ice beaches and should not drink water in the morning and on an empty stomach. The yaks that have just entered the winter and spring pastures are generally fat and fat, so they should try their best to choose remote pastures, mountains and slopes without snow, and postpone grazing in winter and spring near the settlement. There are many snowstorms in winter and spring, so we should pay attention to the weather forecast and return to grazing in time.

When grazing on pasture with uneven or poor quality, the way of loose grazing should be adopted, so that the cattle can feed more grass in a larger area. Winter and spring is the weakest time of the year for yaks. In addition to herding, supplementary feeding should be strengthened in areas where conditions permit. Especially in the blizzard, the temperature drops sharply, and the cold causes serious harm to weak cattle. Generally, grazing should be stopped and supplementary feeding should be made in the shed to make the cattle survive the winter and spring safely.

Management of Yak

The technical level and methods of managing yaks vary greatly in different regions and periods. The general situation adopted in most areas is as follows.

1. Milking

Milking is a labor-intensive work in yak management. Yak milking can be divided into two stages: calf sucking and manual milking. In each milking process, sucking and milking should be repeated twice or milking reflexes are divided into two stages. Therefore, it takes a long time and low labor efficiency.

Because the nipples of yaks are thin and short (the length is only 2~75px), finger-rubbing method is generally used for milking. The milking time of the herd affects the milk yield and the feeding time of yaks throughout the day, so the milking speed should be fast, and the milking duration of each cow should be short, so try to finish milking each cow within 6 minutes. Milking yaks are very sensitive to strangers and odors, so they should be quiet during milking. Milkers, milking movements, passwords, milking order and related systems should not be changed at will.

The method of mechanical milking can not be used in yak milking. Therefore, milkers should master the correct manual milking technology in order to improve milking speed and milk yield. When milking, if the strength of both hands is evenly distributed on the muscles of the forearm, fingers and palms, and with the correct sitting and squeezing posture, the energy consumed by the muscles in intense work can be replenished and milked without feeling sleepy. Otherwise, squatting milking, muscle tension, uneven force, not only slow milking speed, but also quickly feel weak hands.

The muscle strength required to squeeze the nipple during milking is about 15~20kg. If each herd of cows is milked for 2.5 hours and the milking speed is 800.140 times per minute, the tense movements of the joints and muscles of the hands will reach 1.2 ~ 21000 times a day, and the labor intensity is very high, so we must pay attention to protecting the hands. Soak hands and arms in warm water (40 ℃) for 10 minutes, 3 times a day. After soaking, apply a little skin grease, and then massage your fingers, joints and upper arm muscles with your hands to promote blood circulation, enhance muscle metabolism and prevent the disease of both hands.

2. Raising calves

Yak calves are generally naturally breastfed. In order to ensure the normal growth and development of yak calves, the milking amount of yaks must be adjusted according to the grass yield of pasture, calf feed intake, growth and development and health status. Calves can feed on forage after 2 weeks of age, can eat a large amount of food at the age of about 3 months, and the amount of lactation decreases with the increase of age.

Compared with adult cattle, yak calves have shorter daily feeding time and more resting time. Therefore, it is necessary to ensure sufficient rest time in grazing to prevent driving or swimming too much and affecting growth and development. At the same time, it is not suitable for remote grazing, the weather becomes cold, grazing should be harvested in time in case of wind and snow, and there should be a dry shed for sleeping.

In winter and spring, when yak calves are breast-fed to the age of 6 months, they should generally be weaned and raised in groups. If you have been breast-feeding with the mother yak, the baby yak loves milk, and the mother yak takes calves, it is not easy to eat, or even fight for breast milk after the next baby gives birth. In this case, except for the lack of weak dry milk in winter and spring, there is no dry milk period in female yak, which not only affects the safety of mother and calf in winter and spring, but also affects the growth and development of pregnant cow fetus, so it is difficult to improve the production capacity of yak. For yak calves that are less than 6 months old or weak at birth, it is possible to prolong the lactation period before weaning, but the female yaks must be supplemented in winter and spring.

3. Mating and castration

Mating and castration are two important links in yak breeding technology, which not only directly affect the proliferation of yaks, the management of yak herds and the production of products, but also have a close relationship with the selection and matching of yaks and the quality of their offspring. Therefore, enough attention should be paid to the management of yaks.

The natural mating method is generally used in the breeding of yaks. According to the sexual behavior characteristics of male yaks, we should make full use of the competitive ability of male yaks in the dominant position to achieve the purpose of selection, and pay attention to the timely elimination of male yaks which are in the dominant position but the breeding ability is decreased. The mating age of bulls is 4-8 years old, and the mating ability of 4.5-6.5 years old is the strongest, and they seldom mate in large groups after 8 years old. The first mating age of female yak is about 3 years old. The suitable ratio of male and female yaks is 1: 14: 25.

Artificial assisted mating can be used to improve the conception rate and selection in areas with suitable conditions. That is, when the oestrus female yak is found, it is tied in the settlement, its limbs are tied with a rope, put around the neck, left and right two people pull Baoding, and then drive more than 3 male yaks to match. When the female yak was accurately mated twice, the male yak was dispersed and the fresh cow dung was smeared on the buttocks of the female yak to prevent the male yak from climbing across the mating again and loosening the rope.

Yak mature later, castration age later than ordinary cattle, generally at 2-3 years old, should not be premature, otherwise affect the growth and development. When there are fenced pastures or well managed, male yaks can be fattened without castration. Yak castration should be carried out from May to June when the temperature is warm and there are few mosquitoes and flies, so as to facilitate wound healing and lay a good foundation for grazing and fattening in the warm season. Castration surgery should be rapid, cattle down Baoding time should not be too long, after the operation slowly out of grazing, grazing nearby within a week, do not drive violently, and check the wound every day, find bleeding, infection and suppuration, ask the veterinarian to deal with it.

Non-operative castration of epididymis has been used in some areas, and good results have been achieved. The method is that after Baoding, the male yak squeezes the testicles to the upper end of the scrotum by hand to make it close to the abdominal wall, and then uses an elastic rubber trap to tighten the lower scrotum of the testis, so that the testis can no longer drop, because the temperature of the testicles close to the abdominal wall rises, so that the sperm can not survive and achieve the purpose of castration physiologically. As testosterone continues to be produced, male yaks grow faster and produce more meat than male yaks with testicles removed. Male yaks castrated by epididymis still have sexual desire and can be used as trial bulls. Management should be strengthened when grazing in separate groups to avoid the unrest caused by climbing and leaving each other.

4. Pregnancy test

After estrus mating, female yaks are generally able to conceive and abort pregnancy, such as abortion, and there are not many cases of estrus after pregnancy, so there is generally no pregnancy examination for yaks. The criterion for herdsmen to judge whether a yak is pregnant or not is whether the yak will return to estrus in the next estrus. If you want to have a pregnancy test, Cai Li believes that rectal examination is the most simple and easy.

Disease prevention and treatment

1. Yak anthrax

Anthrax is an acute zoonosis caused by Bacillus anthracis. The disease is sporadic or endemic and occurs throughout the year, but it occurs more frequently in warm and rainy seasons in summer and autumn and in low-lying swamps prone to stagnant water.

For many years, yak producing areas have planned and purposefully injected anthrax spore vaccine and achieved good results. From the endemic epidemic in the past to sporadic distribution in local areas. When an epidemic occurs, it is necessary to strictly block, control and isolate diseased cattle, manage them by special personnel, and strictly do a good job in the treatment and disinfection of excreta. Diseased cattle can be treated with anti-anthrax serum or penicillin, tetracycline and other drugs.

2. Yak brucellosis

Brucellosis is a zoonosis caused by brucellosis.

In the aspect of immunological prevention of yak brucellosis, Brucella vaccine M5, 19 and S2 were immunized with aerosol or drinking water successively, and MB32 attenuated vaccine was subcutaneously inoculated with indoor and outdoor aerosol immunization, and the immunization period was more than one year. Pasteurellosis, also known as hemorrhagic septicemia, is a septic infectious disease caused by Pasteurella multocida. The characteristics of the disease are septic changes in acute process and local suppurative inflammation in subcutaneous tissue, joints and organs in chronic process. Most of them are sporadic or local epidemic, which can occur all the year round, but there are more diseases in autumn and winter.

In the early stage, in addition to isolation, disinfection and deep burial treatment, the disease can be treated with anti-pasteurellosis serum or antibiotics and sulfonamides.

3. Yak salmonellosis

Salmonellosis, also known as paratyphoid, is a disease of humans and animals caused by one or more serotypes of salmonella. It is especially harmful to young animals.

Calf colibacillosis is an acute infectious disease of calves caused by pathogenic Escherichia coli. The main clinical manifestations are severe diarrhea, dehydration, collapse and acute septicemia. Colibacillosis of calf yak is common in pastoral areas and mostly occurs in calves 1 ~ 4 days after birth.

There are many methods to treat colibacillosis in calves in China. Yan Zhe-sheng and others used antibiotics, furan drugs and isolated pathogenic strains to make self-made high-immunity serum; Sichuan Ganzi was infused with three needles to prevent and cure calf yak dysentery, and Xizang Changdu area used compound Huanglian to treat calf "diarrhea", and the curative effect was high. Yak infectious pleuropneumonia is a chronic or subacute contagious disease caused by mycoplasma bovis, which is mainly characterized by fibrinous pneumonia and pleuropneumonia.

In 1958, China developed a rabbinized bovine lung disease vaccine, which was proved to be safe and effective, and the immunization period was one and a half years. In order to adapt to the characteristics that there are no rabbits in the vast pastoral areas of China, sheep reactive vaccine was developed and applied in pastoral areas to control the occurrence of yak lung disease.

4. Leptospirosis

Yak leptospirosis is an acute zoonotic disease caused by pathogenic Leptospira.

5. Tuberculosis

Tuberculosis is a chronic infectious disease caused by Mycobacterium tuberculosis in both human and livestock.

Intradermal allergy with tuberculin is the main method for the diagnosis of tuberculosis in yaks (livestock and poultry). However, due to different individuals and different types of tuberculosis in yaks, all diseased yaks can not be detected, and sometimes non-specific reactions may occur. Therefore, a comprehensive judgment should be made in combination with epidemiology, clinical symptoms, pathological changes and etiological diagnosis under different conditions. Fluorescent antibody technique has been used to diagnose tuberculosis.

Regular quarantine should be strengthened and diseased cattle should be strictly isolated or eliminated. If it is found to be open tuberculosis cattle, culling should be carried out. In addition to quarantine, disinfection should be done well in order to prevent infection. Calves were disinfected after birth, isolated from diseased cows or artificially fed with healthy female yaks, and those who were negative at weaning and 3-6 months after weaning were incorporated into healthy herds.

6. Campylobacter disease of calf yak

Campylobacter disease, also known as campylobacter enteritis, is a new zoonotic acute diarrhea disease caused by Campylobacter jejuni, which mainly harms young children and young animals. The main clinical features are fever, diarrhea and abdominal pain.

It is proved that chloramphenicol, tetracycline, dysentery and other drugs have obvious curative effect, and yogurt and whey have control effect on campylobacter disease of calf yak.

7. Yak dermatophilia

Dermatophilia is a zoonotic skin infectious disease caused by Dermatophila in Congo. The disease can occur in yaks of all ages, mainly showing nodules ranging from peas to broad beans in the skin of lips, head and neck, back and chest. After the onset of the disease, there is no significant change in spirit and appetite, showing a chronic process, most of which can be self-cured.

8. Yak dermatomycosis

Dermatomycosis is an infectious disease caused by a variety of dermatomycetes in livestock, poultry and human body surface tissues (skin, hair, nails, claws, hooves, etc.), which does not affect the deep subcutaneous tissue.

Timely take correct treatment, with 5% griseofulvin liquid paraffin oil mixture, once a day, usually 7 days can be cured.

9. Clostridium botulinum poisoning

Clostridium botulinum poisoning, referred to as botulism, is a zoonotic poisoning caused by the absorption of Clostridium botulinum toxin. It is observed that Clostridium yak poisoning mostly occurs in adult female yaks, especially in lactation female yaks.

In terms of prevention and treatment, Qinghai Province has used self-made high immune serum to treat early diseased cattle. Clostridium botulinum type C gelatin vaccine manufactured by Qinghai Veterinary Biopharmaceutical Factory has been listed in the regulations for the manufacture and Inspection of Veterinary Biopharmaceuticals issued by the Ministry. At present, a small dose of Clostridium botulinum type C dry powder vaccine is trial-produced, which is easy to use.

10. Yak foot-and-mouth disease

Foot-and-mouth disease is an acute infectious disease caused by foot-and-mouth disease virus. Mainly against cloven-hoofed animals, with a high degree of contagion. Yaks are extremely susceptible to foot-and-mouth disease, and people can also be infected. The main clinical features are blisters and ulcers in oral mucosa, hooves and breast skin.

Foot-and-mouth disease virus is polymorphic. The prevalent types of foot-and-mouth disease virus in yaks are type O and type A (type A has low mortality, type O has high mortality). Foot-and-mouth disease virus is very resistant to the external environment, especially low temperature. It can only survive for 7 days in summer pastures and 195 days in winter.

11. Yak mucosal disease

Bovine mucosal disease, also known as bovine viral diarrhea, is an acute or chronic infectious disease of cattle caused by mucosal viruses of the genus Plague virus. Most of them showed recessive infection. Acute cases show fever, leukopenia, oral and other gastrointestinal mucosa erosion or ulcers, diarrhea and other symptoms. Chronic cases often have symptoms of persistent infection.

In the aspect of immunological prevention, Chen Yong et al developed bovine viral diarrhea-mucosal disease Oregon C24V freeze-dried attenuated vaccine, which has a good immune effect to prevent yak mucosal disease. But the vaccine is expensive and not safe for pregnant cows. Southwest Institute for nationalities tried the attenuated vaccine of swine fever to immunize yak mucosal disease with satisfactory results.

12. Yak plague

Rinderpest is commonly known as Yangchang plague and daring plague. Is caused by rinderpest virus cloven-hoofed animals, especially cattle knife-changing, feverish, septic infectious diseases. The disease is characterized by inflammation, bleeding, erosion and necrosis of various mucous membranes, especially of the digestive tract.

The government organized a large number of veterinarians to participate in the prevention and control of rinderpest, and organized special forces to develop a vaccine suitable for yak immunization-sheep adapted to goat-adapted rabbinized bovine distemper vaccine (sheep rabbit virus), which controlled the epidemic of yak plague and eliminated rinderpest nationwide by 1955.

13. Yak infectious keratoconjunctivitis

Yak infectious keratoconjunctivitis is an endemic epidemic ophthalmopathy. It usually shows an acute course. The clinical features are inflammation of the red membrane and cornea, massive tears, varying degrees of corneal opacity or milky white.

Domestic use of 35% weak protein silver solution or chloramphenicol eye drops or penicillin solution is effective.