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8 MANAGEMENT OF YAK


Overview

Management systems for yak predominantly follow a traditional pattern dictated by the climate and seasons, by the topography of the land and by social and cultural influences. Methods of keeping the yak vary from the primitive, where herds are allowed to roam virtually at will, to the technologically advanced. In general, a transhumance form of management predominates. During the warm season of summer and autumn, yak are on pastures at high elevations and the herdsmen live in campsites, which they move quite frequently. This gives way in winter and early spring to the grazing of winter pastures at lower elevations that are nearer to the more permanent winter abodes and villages of the herders and their families. The summer grazings are much the more extensive of the two.

Until fairly recent years, the predominant practice in China was for all yak from several families in one or more than one village to be pooled for purposes of management but subdivided into four groups: lactating cows, dry cows, replacement stock and steers (pack yak). Since the implementation in China of the "Household Responsibility" system, which includes leasing parcels of land to the herders and private ownership of the animals, the herd of each family is rarely subdivided, although the adult females are likely to be managed separately from the rest of the animals. Some pooling of resources among small family groups may still occur.

The proportions of each type of yak in the herd, the herd structure, can profoundly affect the output of milk and meat from the herd.

Grazing traditions rely on accumulated experience including knowledge of the particular properties of different types of pasture vegetation. Over-grazing has become a recognized problem, especially on the winter pastures, because an increase in the yak population has occurred, at least in several of the provinces with yak in China. This increase is due, in part, to official encouragement of extra food production and in part to the fact that many herders, perhaps most, still equate numbers of animals with wealth and status, irrespective of the intrinsic merit of the animals or their productivity.

To assist in the management of yak, there is a small range of fixtures, mainly at the winter quarters, in the form of pens and enclosures usually made of mud, turf or faeces. Wood, because of its scarcity, is used sparingly in the plateau areas. But in the alpine areas, wooden enclosures are found more often. Pens are usually associated with a tunnel-like passage for restraining animals during vaccinations or other treatments; a pit for dipping both yak and sheep is normally available; and a crush to restrain cows for mating is used in places where hand mating is practised.

Herdsmen train yak to obey commands both by voice and by use of small stones that are either thrown or projected with a sling. The purpose is to allow one person to control a large herd. The herder normally stays with the herd to protect it from attack by wolves, especially at times of calving, and to prevent the herd from straying onto another's territory. At night, the animals are tethered near the campsite to protect them from predators and for purposes of milking the cows.

During the warm season, yak are sent out to graze the summer pastures early in the morning and brought back to the campsite as late in the day as possible. In winter, the reverse happens with late out and early back. Milking, practised only during the warm season, is done once a day or, in some herds, twice. The method of calf rearing revolves around the frequency of milking of the cows. Milking three times a day is also practised for cows that do not have a calf at foot.

Apart from the important task of controlling the grazing and protecting the herd, the other main tasks of the herders involve: calf rearing, milking, supervising mating, assisting with calving (but usually only for cows giving birth to hybrid calves from "improved" breeds of cattle that tend to be too large for unassisted delivery) and harvesting the fleece (most often a combination of combing out the fine down followed by shearing or shearing alone). Other routine tasks include dipping animals against external parasites, vaccinations, castrating males and training of pack animals.

Yak and hybrids of yak and cattle are also used for ploughing for eight to ten hours a day during the planting season in areas where grazing land is combined with land suitable for cultivation. Such animals are given supplementary feeding of straw and grain. Animals used for ploughing may also be used later in the year for carrying loads on long journeys over often-difficult terrain. When working, such animals may walk continuously for seven to ten days before a rest of one or two days.

Introduction

There is no single management system that applies to all yak over the large area of its distribution. Methods differ according to country and region, influenced by altitude, climate and topography. There are differences in management related to culture and religion. Proximity to centres of population, which provide a market for yak products, also has an effect on management, since it determines whether products are used primarily by the families herding the yak or whether certain products, like milk, are exploited more for the sale of, for example, butter or cheese. (Figure 8.1 shows milk collection in progress) In some countries, for example Nepal, tourism provides outlets for products from the yak, including handicrafts usually made from the "wool".

In other countries, such as Mongolia, meat from yak is an important commercial product with slaughtering at centralized but often distant abattoirs, again affecting management practices. Generalizations about the management of yak and the uses to which yak are put are bound to be an oversimplification in respect of any specific case.

Figure 8.1 Milk collection (transported in churns) (Photo courtesy of Gerald Wiener)

Management of yak ranges from the most primitive, seemingly unchanged by the passage of time, to the technologically quite advanced practice. There are three main types of yak farming systems on the Qinghai-Tibetan Plateau of China, namely nomadic, semi-settled and the so-called "small-holder". All of them involve a transhumance type of herding with different pastures used in the warm and the cold seasons.

The nomadic system is a traditional one dating back to ancient times. Under it, entire herds are kept together and largely left to roam the ranges to which herdsmen will go, in autumn, to hunt and shoot well-grown steers or bulls for meat. The semi-settled system was the most common system from the early 1950s to the late 1970s. With the settlement of herders, some pastures started to be fenced and supplementary feeds for winter use, such as oats, started to be planted where possible, and herd size began to be adjusted according to the availability of grazing land. Small-holder farming has been developed in China since 1980 and is expected to become the dominant system under the policy of "Household Responsibility" (Dong et al. 1999). This system requires yak farmers to rent grazing lands from the government - the area depending on family size. The rent is tiny and the contract is valid for 50 years.

It is hoped that the small-holder system, with its potentially greater control over grazing land and the additional responsibilities placed on herders, will encourage the adoption of newer practices in yak management. These would include supplementary feeding, more controlled rotational grazing, greater disease control, management aids to mating (e.g. A.I., where herds are accessible for this technique) and perhaps a greater use of hybridization with "improved" breeds of cattle (but see Chapter 3 for possible constraints). The expectation is that such measures would lead to a further increase in output and off-take from yak - especially when compared to the nomadic system which nowadays may account for no more than ten percent of the total yak population in China (Dong et al, 1999).

According to Dong, improvements expected, relative to the semi-settled system, would be in the size of the animals, in aspects of reproduction, in survival and in milk yield. Even if such improvements were not large at the individual herd level, they could lead to a significant cumulative increase in production over the yak population as a whole.

At experimental stations concerned with yak, most techniques familiar to modern cattle husbandry are under consideration, though they are not always appropriate to traditional yak husbandry or the associated environment - and not therefore necessarily practised outside the experimental situations. Multiple ovulation and embryo transfer are appearing on the scene, but only as an experimental tool in restricted circumstances. Similarly, at the scientific level, the concepts and development of new pasture management techniques are clearly recognized (e.g. Ren and Chu, 1993; see also Chapter 13). Miller (1990) has taken the view that for the vast grasslands of the Qinghai-Tibetan Plateau, a great potential exists for improving the herbage productivity of the rangeland and its livestock output, provided improved rangeland management policies are developed and implemented.

With so wide a spectrum of local environments and management practices, what will be attempted here is to provide merely an overview of what must still be regarded as standard practice for most yak, at least in the areas of China where the majority of the yak live. Where countries outside China or specific provinces within China, differ in major ways in their yak husbandry practice, or in specific aspects of yak production, this is referred to in Chapter 11. In all areas, the climate and the seasons dictate to a large extent what happens to yak.

Herdsmen's activities according to seasonal cycle

Yak pastures and grazing habits

A full description of the rangeland and the plant species and their distribution will be found in Chapter 13. Only those aspects that reflect directly on the management of the yak are discussed here.

In the plateau areas, the grassland used by the herdsmen of a village can be broadly divided into two categories: what is used in the warm season (summer-autumn) and what is used in the cold season (winter-spring). The local climate and character of the land determines precisely where the areas of grassland for different seasons are located and for how long in the year each is grazed. In general, the warm-season grazing is at the higher altitudes, often on the northern slopes of the terrain and furthest from the settled homes of the herdsmen and their families. In late May or early June just after calving, the yak start to feed on the high quality and quantity of forage of the summer-autumn pastures where the cows suckle their calves, restore their weight loss and then fatten under good nutritional conditions. In late October or early November, as the production and nutritive values of natural forage decreases, the yak return to the winter-spring pasture. The cold-season grazing is then closer to "home" and in more sheltered, south-facing parts at lower elevations. The winter-spring pasture is grazed from early November to the following late April. Due to the low quantity and poor quality of the natural forage, the yak lose body weight, and in harsh, cold seasons deaths are not uncommon - quite apart from the extensive losses in periodic "snow disasters" (Wiener, 1996; Long and Ma, 1996). Supplementary feeding, when available, together with shelter, can ameliorate these problems.

The alpine areas are more varied because of the topography. The area of grassland occupied by the yak of a village can be quite large and is likely to be distributed across several mountain ridges separated by valleys. The ridges may well be above 4 000 m in altitude and the valleys much lower. Consequently, the grazing areas are more subdivided than in the plateau regions. In the alpine regions there is a separate grazing area for each of the four seasons of the year. The summer pastures are the extensive alpine meadows at the top of the mountain ranges. The spring and the autumn pastures are occupied for relatively short periods only by the animals in transit between summer and winter grazing areas. For that reason, the spring and autumn grazing areas tend to be small and are mostly on the hilly ground. The winter pastures, or "winter house" as it is called by the herdsmen, is situated in the gullies and, when possible, at the side of a forest for additional shelter. In most areas, the spring and autumn pastures or the spring and winter pastures are combined to form a three-seasonal system (see Chapter 13).

When yak are kept in areas with swamps, there is another variant in the use of grassland. The actual swamps or semi-swamps turn green relatively early in the year because they are generally at the lower altitudes.

The yak have an opportunity to graze fresh tender plants (with a high proportion of Kobresia and other Cyperaceae spp.) in the areas reserved for grazing in the spring. Summer-autumn pastures are then again at higher elevations and the winter pastures on lower ground nearer the settled areas of the herdsmen's families.

Traditionally, the nomadic way of herding yak was to keep the entire herd together, irrespective of age and sex, and to allow the yak to graze together with sheep and horses. The herdsmen lived with their animals and during the growing season moved with them as necessitated by the availability of grazing and water. In a vivid account of the grasslands of the Tibetan Plateau, Miller (1990) described the pastoral grouping and management of yak as well-adapted responses to different range and environmental conditions and ecologically sound and sustainable - while, at the same time, noting room for improvements.

The traditional use of different pastures at different seasons and the periodic movement of the animals to new grazing sites (see section, Utilization of grazing) represent some of the elements of "modern" rotational grazing systems. Official encouragement and financial subsidies are now provided for fencing of land with the intention that this should optimize pasture utilization and reduce parasite infections. In the past, such fencing to control grazing was rare largely because of the high cost. Fencing of land has further accelerated the move towards a more settled existence, starting around the 1950s, and has brought with it the division of herds for purposes of grazing and management described earlier (see also Chapter 12 for other possible consequences of fencing).

Herd ownership in relation to management

In China, the land is owned by the State, but the animals are usually owned by the herdsmen. The predominant practice until recent years was for several families or even all the families of a village to share the same pastures. If stocking rate in a particular area of the country was low, the number of yak that could be owned by a family was not restricted. However, in most parts of the country this was not so. The number of yak allowed to each family depended on family size, and the rights to grassland were fixed by agreement. There were penalties for transgressing the rules. Notwithstanding, there has been an increase in yak numbers in many parts of the yak territory. This will have arisen because of the encouragement to increase food production in China and because of a traditional view of yak herdsmen that equates the number of animals owned with status and wealth. This increase in numbers has, in turn, accentuated fears of overgrazing of the grasslands (see the following section). The most recent moves to fencing of land and its allocation to individual herders (see previous section) in turn creates both new opportunities and new problems in yak management (cf. Chapter12) and it is no longer certain that the yak of several families or of a whole village can be managed together.

Yak herd management

Before the Household Responsibility system was implemented in yak territories of China, both the animals and the grassland belonged to the State. In those circumstances, the total yak herd, as merged from the animals of several families and one or more villages, was usually divided into component herds. There was 1) the lactating-cow herd (the dairy herd, the largest of the component herds usually numbered between 100 and 150 head in the plateau areas and between 50 and 100 in the alpine areas. The dairy herd was normally allocated to the best-quality pastures available to the village). There was 2) the dry-cow herd (the "Ganba" herd) and 3) the group representing the younger replacement animals - those that had been weaned and separated from their dams (the "Yaer" herd). The herd of replacement animals was further divided to separate the males from the females. And there was 4) the steer herd (pack yak). There was no special herd for the bulls, which live with the breeding females during the breeding season and mostly alone at other times. Also, there was not usually a separate group for animals intended for slaughter for meat. Usually, the "meat" animals are merely the cull females and any chosen as suitable from among the steers and the bulls. (This would differ in countries where large-scale commercial fattening and slaughtering of yak is practised; see Chapter 11.) The hybrid F1 and backcross steers are distributed, as appropriate, among the groups used for riding, as pack animals or for draught.

Following implementation of the small-holder system, under which herders own the animals and lease the land, the family herd is rarely divided into several subgroups because of labour and herd-size restrictions. However, subdivision of the total yak herd into two groups - adult females together and the rest of the animals in another group - is still practised in some yak-raising areas by small groups of families and their relatives (Young calves remain with their dams up to weaning, which is most often in their second warm season of life when they are between 12 and 18 months old; but it can, of course, be sooner). After weaning, whenever it is, the young animals are incorporated into the mixed herd.

Other management practices such as time of weaning, provision for supplementary feed, culling strategy and so on, vary depending on herders' experience and knowledge.

The herd divisions described earlier applied primarily to daytime grazing in the warm season. At night, the yak tended to be divided again by family ownership and the different types of yak mixed and kept near the family tent. During the cold season, the families collect back their own yak to keep them on winter-spring pastures, which nowadays are increasingly fenced. As ideas, based on newer concepts of feeding and management, are accepted by herdsmen, it is likely that new systems of management will develop. This process is already apparent in some cases where specialization of production is emerging.

Yak herds vary in size depending on families. Some families have doubled the size of their herds since the time when the animals first came into their private ownership, while others have reduced the number of yak or even given up herding altogether. The herders who are now without animals have generally either leased their rangelands to others or chosen to work for others. Some of them have gone to townships or cities to find work.

Utilization of grazing

Formerly, during the warm season, a yak herd was typically moved every 40 - 60 days depending on the state of the grass and the size of the herd. Nowadays, this procedure is common only in some of the vast plain areas. The direction of movement of the herd and the route chosen is usually the same every year and the distance between campsites is generally less than 20 km. There are two ways in which the move can be made: One procedure is to move the livestock and the people, with their tents and belongings, all together in one move, until the new campsite is reached. Under those circumstances, the animals get virtually no chance to graze on route. The other way is to move the people and belongings to the new campsite first, establish the site and then move the yak gently in the course of a day's grazing toward the new campsite, which they reach at night. The former procedure is prevalent when the distance between the sites is long; the second method is more common when the distance is relatively short.

During the cold season, movements from one site to the other are few - not more than two to five over the whole period. But if the yak herd is small, or if yak are kept in pens with supplementary feeding, there may be no move at all over the whole of the winter and early spring.

Yak are versatile grazers. As already noted (see Chapter 4) they will take a variety of different herbage and are equipped to do so by their different feeding habits. This ability of the yak contributes to a better utilization of the total grazing. As pointed out by Cincotta et al. (1991), from a study of diet selection on the Tibetan Changtang, yak consumed a variety of forages avoided by sheep and goats, but these other ruminants consumed large quantities of some types of browse largely ignored by yak. As reported from many other situations, complementary grazing by a mixture of animal species generally leads to a better overall utilization of the total grazing resource.

Grazing traditions

Much of the grazing management of yak is part of the ingrained tradition of the herdsmen, developed through a long history of experience going back over the centuries. Much of this tradition has a sound scientific basis and is an effective means of utilizing the resources of a hostile environment to best advantage. Thus, herdsmen know well how to exploit changes in grass growth. For example, there is the use of swamp areas for early grazing in spring followed by a period on grassland with Ophiopogon japonica, said to cause de-worming and stimulate oestrus. Bog-meadows in June with yellow-flowered herbs of Kobresia, Trollius and Caltha spp. increase milk yield and turn the raw butter a desired orange colour. In the autumn, grazing on seeded grass is used to build up body condition to withstand the winter and early spring. In the cold season, yak are pastured in the most sheltered and warm (a relative term!), south-facing areas with as much wilted grass as possible to allow the animals some sustenance, which they obtain by scraping through the snow and ice. Many of these practices are enshrined in local proverbs and sayings that tell succinctly what to do and when.

Problems of overgrazing

Notwithstanding the great local experience of the herdsmen in exploiting their grazing territory to best advantage, serious problems from overgrazing are developing in the utilization of the yak pastures in some regions (but see also Chapters 12 and 13).

As referred to earlier, yak numbers increased over the years, at least in China. The resulting increase in stock numbers has put increasing pressure on the pastures, particularly the winter grazing lands. The winter pastures cover a smaller area than the summer pastures, but also have to sustain a larger number of animals, because numbers are always at their highest after the calf crop of that year. The winter pastures in particular, therefore, tend to be increasingly often overgrazed.

The consequences of overgrazing in terms of grassland degradation are discussed in Chapter 13.

Overgrazing of grassland has been accentuated by the fact that the income from sheep meat and wool has declined and that from yak milk and meat has increased - with a consequent decline in sheep numbers relative to yak. This in turn has created a further imbalance in the utilization of the land. In Ruoergai county of Sichuan, to take this area surveyed by Cai Li as an example, yak numbers increased between 1979 and 1984 (from 230 000 to 325 000), while during the same period, sheep numbers fell (from 619 000 to 532 000). An optimal ratio of cattle to sheep for that particular area was calculated to be 1:2.9 (more commonly 1:3.2) (Lei et al., 1986) but had been reduced to 1:2.2 by 1984. Thus, not only had stocking density (per adult animal unit) increased, but the stocking had become imbalanced in terms of the different contributions to grazing selection made by yak and sheep. A partial alleviation of the problems of overgrazing may come from changes in herd structure and from the use of supplementary feeds.

Adjustment of herd structure

The structure of yak herds is all too often a matter of chance with the milk herd, steer herd, replacement herd, etc. not in best proportions for optimizing output. The opportunities for making changes depend largely on reproductive and survival rates and decisions on the ages at which to sell or slaughter surplus animals (or animals destined for meat). If procedures were adopted to optimise the population structure, as recommended by Cai Li et al. (1986) and many times since by others (e.g. Ji et al., 2002), it should be possible to increase overall productivity from the land while decreasing the total number of animals required. Measures would include the earlier slaughter of steers and culls and changing management procedures so as to increase the proportion of the productive animals (the lactating cows and the hybrid dairy herd) and reducing the proportion of the unproductive animals. For example, Zhen (1994) used linear programming to obtain an economically optimum structure for yak herds. Zhang, T. (1994) has pointed out that readjustments, which he describes in his study, can lead to substantial increases in output from the herd. For example, increasing the proportion of cows in the herd from a commonly found 35 percent to an attainable 50 percent would increase the milk output by 43 percent and other off-take of surplus stock by 10 percent - though with a concomitant reduction in off-take from the beef herd.

Not all localities have the same opportunities for increasing the proportion of productive cows at the expense of less productive animals. Availability of feed, climate and length of growing season, nature of the grasslands, etc. all play a part. But even small changes in the herd structure were shown, in these studies, to lead to useful improvements in off-take from the herd. This was demonstrated at the Datong Yak Farm where a 5 percent increase in the proportion of cows in the herd between 1985 and 1989 was accompanied by an increase of 14 percent in milk output. The changes that are desirable in herd structure will also depend on whether milk or beef is the primary consideration. However, attaining an optimum herd structure among yak herds in general is an ideal not yet in sight in spite of the continuing references to the need. But the related concerns about overgrazing must be addressed before permanent damage is done to the grasslands.

Apart from the wider degradation issues discussed in Chapter 13, Winter et al. (1992, 1994) provided a particular example, attributed to overgrazing, that highlights the wider problem. The report relates to widespread deaths among yak in Bhutan, found to be due to pyrrolizidine alkaloid poisoning. The plants causing this (most especially some species of Senecio) are not very palatable and are, normally, avoided by yak or taken in only small amount. However, the plants had become prevalent through overgrazing and the yak, through hunger it was thought, consumed the plants in lethal quantity.

Supplementary feeding

There are a few opportunities for supplementary feeding of yak, except perhaps in the agricultural areas (see Chapter 14). Surplus herbage for hay or silage is not widely available, nor the equipment to make it - at least in the major yak-producing areas. A little hay is usually made but it is normally given only to sick or very weak animals towards the end of winter. Additional feeding when given can elicit a response in terms of reduced weight loss (over winter) or increased growth or milk yield, as noted from a number of trials (described in Chapter 6) and also in a study that involved winter feeding under shelter with the provision of hay and mineral licks (Liu and Cheng, 1994).

The use of urea molasses blocks, a kind of protein supplement, has been widely recommended in recent years for yak production in alpine regions (Xie et al., 1997; Wang, et al., 1997; Zhang, D. G, 1998). In these alpine regions, protein deficiency in forage is a serious problem due to a shortage of legumes in the swards of the natural grassland (Dong, 2001; Pu, et al., 2001). The cost-effectiveness of such feeding still requires investigation both in respect of home-grown and purchased feed. In Buryatia, for example, as reported by Katzina (see Chapter 11, part 2) it is customary to give supplementary feeding to yak calves during their first winter of life. Consequently, these animals do not lose weight over that period. This could account for the fact that the yak females subsequently breed for the first time a year earlier than in most other situations and that the steers are slaughtered at an earlier age (yak in North America provide a similar example; see also Chapter 11, part 3). It is important, therefore, to judge the effectiveness of feeding not only by immediate responses but also in terms of any long-term effects.

Equipment and penning

Generally, there is little equipment to assist the herdsmen in the management of yak on range. The most usual provisions are a dipping pit used for both cattle and sheep; perhaps a silo or silage trench for use mainly by sheep; a corral with a tunnel-like passage to restrain animals for vaccinations or other treatments; and there may be a simple crush to hold cows that are intended to mate to particular bulls or to inseminate artificially. Pens are also created to provide shelter. Such pens and enclosures are used only at night and usually only during the winter and spring. They are always at the campsite or close to the habitation of the herdsmen and their families. The pens can be of various types of construction with differing degrees of permanence.

Mud pen

This is a relatively permanent construction built near the habitation of the herdsmen or at the winter campsite. It is used primarily for the cow herd, including hybrid females, and it is also used for the replacement females. The area is usually 15 x 15 m with a wall 1 - 1.2 m high, but the size can be as large as 30 x 20 m. Most of the mud pens have an additional shelter area constructed at one side of the pen facing the sun and providing extra protection from the wind. This extra shelter is constructed from a layer of clay on wooden boards knitted together with wicker. Such a pen is illustrated schematically and in a photograph in Figure 8.2.

The mud pens can stand alone, though more usually there are two or more built together and often joined by a passage with mud walls or wooden fence. A gate or gates keep the stock apart in the different pens. If several pens are connected to each other, the last pen will end in a long tunnel-like passage used for restraining the animals for vaccinations or other purposes. The passage can be roofed or open.

Faeces pen

This is a temporary structure, built and used only during the cold season. Fresh yak faeces are piled up near the campsite in a layer of about 15 - 20 cm deep every day. The first layer freezes solid overnight before the second layer is added.

Such a pen can be completed in a few days. There are two types of faeces pen: One has four walls to keep out wind and snow and provides a relatively large area used for adult yak.

Figure 8.2 Mud (wall) pen with wooden shelter a) schematic

Figure 8.2 Mud (wall) pen with wooden shelter b) photograph

The other is smaller, built on a horseshoe-shaped foundation with a diameter of about 1 m and looking, from the outside, something like an upside-down earthenware jar. It is built up gradually to its final 1 m height and is used to hold calves. The open end has its back to the prevailing wind. A wooden stake is used to tether the calf. Hay is put inside the pen to make it warmer for the calf. When the temperature starts to rise in the spring, the faeces thaws and pens made from it fall apart, to be rebuilt in the following winter.

Turf pen

To build pens with turf, herdsmen select a position on the winter pastures that faces the sun and is relatively sheltered from the wind. The height of the turf walls is at least 60 cm, though usually higher. This type of pen is used to give some shelter to pack yak and some bulls. The structure is semi-permanent but needs to be repaired each year.

Wooden compound (or corral)

Wood is in short supply on the plateau where most yak live. Therefore, wooden enclosures are often only an adjunct to a mud pen and within its perimeter. The wooden enclosure may be roofed or not. In the alpine areas, wood is more abundant and the compound may be built independently. The structure is of small wooden bars and provision is made for holding hay. During the warm season, these wooden enclosures are used to keep the calves isolated from their dams at night, while the adults graze in preparation for milking the following morning.

Other shelters

Tents made of yak hair are also used for calves in the pastoral areas. In the alpine parts, for example in Jiulong county of Sichuan, there are small shelters, called cattle shelters, found as part of the permanent buildings of the campsites. They are used by herdsmen and milkers and for processing milk and storing milk products. Such shelters can vary in area from 10 - 20 sq m and are surrounded by a stone wall that is 1.5 m. high. Boards or bark are used for the roof. These shelters are in use whenever the herd comes to the campsite.

Management of yak herds on the range

Controlling the herd

Temperamentally, yak are at varying times wild or timid, cowardly and yet aggressive. Another part of the yak's character is its strong herding instinct. All these aspects have to be taken into account in training yak to obey commands so that a single person can control and manage a large herd. Because of the yak's timidity, the herder cannot follow too closely behind the herd for fear of it scattering. The practice of the herder is to select a high spot of ground, overlooking the herd while it is grazing. In this way, he can protect the yak from wolves and prevent the herd from straying onto grazing land set aside for other herds.

The herdsmen use special summonses to call the yak and they throw small stones to make straying animals return to the herd. A stone thrown by hand may travel 10 m, but using a sling - as is a common practice in many parts - can project a stone more than 100 m in the hands of a skilled user. Both the sound of the stone flying through the air at great speed and the sound of the sling, like the crack of a whip, provide a warning signal to the yak. The direction from which the stone comes allows the yak to know which way to go and whether to advance, muster or disperse. The sling (illustrated in Figure 8.3) used for projecting the stone is woven from yak hair and down, or sheep's wool. It is 100 - 120 cm long and has an elliptical net at its centre (7 x 15 cm) to hold the stone.

Figure 8.3 Sling of hair and yak down (or sheep wool) used to project stones used in herding yak

However, the management of yak herds on the range varies from region to region. Landforms (mountain and plain) also lead to different approaches to managing yak herds, even in the same region. Nowadays, labour availability has a profound influence on patterns of yak herd management on the range. In general, there are two systems, which, for simplicity can be categorized as a) yak tethered at night and b) adult animals graze freely at night. Figure 8.4 illustrates a typical, or traditional, system in which yak are tethered at night near the campsite, after returning from the grazing lands, to protect them from attack by predators or from thieves and to have the cows ready for milking in the morning.

Normally, the tethering site is square and enclosed by several layers (circles) of the rope of yak hair or skin with the wooden bars at the corners. The yak is tethered to the ropes with a 40 - 50 cm (for cows and calves) or 50 - 60 cm rein (for pack yak and hybrids). There is a gap of approximately 2 m wide between any yak and 5 m between two stretches of rope. As shown in Figure 8.4, strong, aggressive pack steer and timid young cows are generally tethered to the outside, furthest from the tents, and the milking cows are tethered close to their calves (the calves in this system, cannot suckle). Once the position of each yak on the tethering sites is fixed, the yak will find their own way to their allotted place after returning from grazing.

Figure 8.4 Sketch map of the tethering sites of yak herd

Daily schedules

The grazing schedule for yak differs with the type of herd (if subdivided) and with the season. For herds of dairy yak there will also be a variety of different schedules depending on the frequency of milking and on the particular calf-rearing practice. In sending yak out to graze, the guiding principle for the herdsmen is: "Early out and late back in summer and autumn, late out and early back in winter and spring."

The mixed herd (including pack yak and the replacement animals) is left out at pasture both day and night during the warm season. It does not return to the campsite during that period - but the herder needs to visit such a herd two or three times a week. Also during the warm season, the lactating females need to recover their body condition after the rigours of the previous winter and spring, if they are to give milk, rear calves and mate again. For that reason, the cows are allowed to graze both during the day and night, while, as a rule, the calves are penned overnight (but cf. Table 6.7 for the effects on growth of calves grazing alongside their dams overnight). This pattern of management is a typical system of free grazing at night (see also the ensuing section on management).

The following are some examples of the daily (summer) schedules for yak milked once, twice or three times a day in different localities.

· Once-a-day milking (practised in Ninai township of Jiulong county, Sichuan). The calves graze with their dams and suckle them (except at night).

Hours:


0500 - 0700

Yak cows recalled from their night grazing to the campsite where they are mustered without tethering.

0700 - 0900

Milking; release calves from their overnight wooden enclosure.

0900 - 1800

Animals graze the alpine grassland. Calves graze with their dams and suckle. Yak graze freely, drink water, rest and ruminate.

1800 - 2000

End grazing on alpine pasture; herd returns to campsite, calves enclosed in the wooden corral.

2000 - 0500

Yak cows allowed to graze freely on pasture near the campsite.

· Twice-a-day milking (practised for lactating cow herd in Muye township of Mashu district, Ganzi county, Sichuan). Calves are reared artificially in some such herds.

Hours:


0500 - 0700

Animals grazing near campsite on grass with dew.

0700 - 0900

Yak called in for the first milking. Calves released from their overnight wooden enclosure then allowed to graze with their dams and to suckle until second milking.

0900 - 1300

Yak driven to far-away pastures at higher elevations and allowed to walk slowly and gradually back downward while grazing.

1300 - 1500

Herd driven to a watering place, allowed to rest and ruminate.

1500 - 1900

Herd driven back to a point about halfway up the hill and allowed to graze at will.

1900 - 2000

End of grazing; return to campsite with drinking water on the way.

2000 - 2100

Yak tethered at the campsite, second milking.

2100 - 0500

Yak cows released to graze near campsite.

Three times-a-day milking (practised at Xiangdong Livestock Farm in Ruoergai county, Sichuan). Calves suckle their dams.

Hours:


0500 - 0800

First milking of cows.

0800 - 1300

Yak cows allowed to graze freely and have access to water at a distance from the campsite. Calves remain tethered at campsite or are tied together in pairs and allowed to graze near camp.

1300 - 1500

Yak cows driven back to campsite; second milking (without tethering).

1500 - 1900

Calves allowed to graze with their dams, away from the campsite in good weather and near the camp if weather is poor. Calves are given the opportunity to suckle and also to drink water.

1900 - 2100

Grazing period ends; calves are separated from their dams after another opportunity for suckling. The calves are then tethered to a long rope at the campsite (see Figure 8.5). The cows that have no calves - the "half-lactating" females and those that have lost their calf and are not fostering - are milked for a third time.

2100 - 0500

Calves remain tethered overnight. The cows may either be tethered or not, depending on the topography of the land and the ease with which they can be driven back to the campsite in the morning.

Management of the individual animal

The management practice and extent of technical input varies greatly among areas. A few of the most common practices are as follows:

Calf rearing

Normally, yak calves are suckled by their dams. Artificial rearing occurs only if the dam of the calf has died and no foster dam has been found or in some cases also where twice-a-day milking is practised.

Fostering is attempted when a calf has lost its dam and another cow has lost its calf. Because of her strong maternal instinct, a yak cow that has lost her calf can be persuaded to accept another by smearing the calf to be fostered with her milk or to place the hide of her dead calf on the intended fosterling. Smearing salt on the calf will also stimulate the foster dam to smell and lick the new calf and adopt it as her own.

Figure 8.5 Tethering of yak calves to a rope

Artificial rearing is accomplished with a feeding bottle made of a yak horn without its tip and with a teat, the size of a thumb, made of yak hide attached to the end of the horn. The "bottle" is filled with milk and the calf sucks normally. The timing and the length of time of such feeding has to take account of the normal suckling behaviour and also the need of the calf for young grass so that it can establish grazing behaviour and rumination. Care is taken by the herdsmen to prevent calves sucking each other, as blockages of the abomasum pyloris can result from careless practice.

With normal rearing, the dam (or foster dam) is not milked for ten days, or even a month, after calving, during which time the calf obtains first the colostrum and then all the milk from the dam. When the dam starts to be milked, the calf continues to suck, to the extent permitted by the regime and graze alongside its dam. Yak calves start to nibble grass at seven to ten days old, but they have not been observed to ruminate before the age of 12 days. At night, as already noted, the calves are separated from their dams, except from dams that are not milked because they produce too little or because they are ill.

During the cold season, the cows are not milked and their calves stay with them all day and usually obtain a small amount of milk by suckling.

Calves of cows that have become pregnant again are weaned at six months old. However, calves whose dams have not conceived again that year, or do not produce a new calf in the following year, stay with their dams through a second summer; generally that is the majority of calves.

To achieve weaning, the cows and the calves are separated into different herds. In cases where the calf persists in trying to suckle, a piece of wood about 20 cm long, sharpened at both ends, is pushed through the nasal septum between the nostrils. This is removed only when the calf has stopped its attempts at suckling.

Milking

The teats of yak females are small and have to be squeezed quite hard between the fingers to extract milk (cf. Chapter 6). Milking takes place at the campsite. If the calf is tethered, the cow will be tied up, too, unless the calf is kept in a corral. The cows that are not tethered usually graze all day and yield more milk than those that are tied up for part of the day.

Tethering is done by hitching a neck rope by a wooden peg to a long rope with many rings. The rope is fixed to the ground at the campsite. (Cows are trained to become accustomed to neck ropes and to being tethered from the time they are calves). Milking the cow takes place where she is tethered. After a short time, the yak cows remember the position along the rope where they are to be tied, and they will quickly learn a new position, if given one, after a move to another campsite.

In some areas, milking also takes place in stalls. The milkers call the yak by using charming, eloquent names given to them at their first milking. A little barley powder mixed with salt may be used as an added incentive to tempt the cows into the stalls. Once there, the cow is hitched by her neck rope to a wooden pole and milked.

The milking stall is usually constructed with a left wall and a front wall of stone (100 - 120 cm long, 60 - 80 cm wide and 60 - 80 cm high) and the other sides open. The floor has stone slabs, and there is a wooden pole for securing the animal (see Figure 8.6).

Figure 8.6 A milking stall with stone slab floor, stone wall and pole for tying animal

Yet another variation of milking practice occurs when yak cows are not tethered at all. The milker goes to the cow, anywhere on the campsite, with bucket in hand and calf in tow. The forelimbs of the cow are tied with a short rope prior to milking.

The milking reflex is stimulated, in the first instance, by the calf poking the udder and being allowed to suck a little until milk let-down occurs. The calf is then removed a short distance but still within sight of the cow, and hand milking starts. The reflex has to be restimulated a second time, after a little more than half the milk has been extracted, by using the same procedure with the calf.

The milker normally squats on the right side of the cow with the pail hung from a hook on a girdle, as illustrated in Figure 8.7. The milker uses a little butter, which has been spread on the side of the pail, to lubricate the teats and milks at about 80 squeezes per minute. As milking speed can affect the milk production and grazing time of yak, the aim is to finish milking as quickly as possible (on average, not more than six minutes per yak). As yak are very sensitive to smells and voices, it is best if the milkers are not changed often and that they remain silent during milking.

Figure 8.7 Milking in progress

A small number of cows cannot be milked because they are too ferocious and protective of their calf.

Mating of female yak

In pastoral areas, mass mating of the female herd is the normal practice with between 5 and 6 yak bulls to every 100 females - though more bulls may be used in some areas; for example, Dubrovin (1992) reports the use of 8 yak bulls per 100 females in the Caucasus. This system allows competition among the bulls for mates and is part of the selection process. In some areas, artificial assistance is given to the mating process. In such cases, as when a yak cow is found to show oestrus (often by using a teaser bull), she will be caught and her forelegs tied and a rope placed around her neck. The cow is then restrained in a breeding crate or held by two men, one on each side of the cow. Three or more bulls are then driven towards the cow and allowed to compete for the mating. After the cow has been served twice (by the same bull or once each by two different bulls), the bulls are driven away and the cow is released after smearing her rump with fresh faeces to deter further mounting and mating. An advantage of such artificial restraint of the cow is that it allows selected mating to be made; but a disadvantage is that accidents and damage occasionally occur to the cow in these circumstances.

In agricultural areas, only one yak bull is normally allocated to a cow, which is restrained for the actual mating. This is safer than the competitive mating procedure of the pastoral areas and helps the herdsmen to achieve their selection objectives.

Artificial insemination is practised mainly for interspecies hybridization, as referred to in Chapters 5 and 7, and has been refined since the 1970s. Frozen semen is used from bulls of other cattle species but is also now available from yak bulls, chosen for use in improvement programmes (including the wild yak bulls referred to in Chapter 3). By experiment and experience, techniques for collection and use of semen have had to be adapted to the yak situation and the climate. In particular, great attention has to be paid to the safety of the person undertaking insemination of yak. The yak cow has to be restrained in an insemination crate (see Figure 8.8). The temperature of the thawed semen has to be maintained to prevent cold shock since the ambient temperature in the early parts of the morning can be as low as 0°C even in the warm season. For the same reason, particular attention has to be paid to the temperature of the inseminating tube and syringe. Deep insemination with the help of rectal palpation can improve the pregnancy rate. Inseminated yak cows have to be kept away from the yak bulls. If a yak bull mounts a yak cow that has just been artificially inseminated with the semen from a cattle bull, she will usually produce a yak calf, because the yak sperm seem to win in the competition to reach the egg.

Figure 8.8 Artificial insemination of yak

Pregnancy detection

Abortions and disease during pregnancy are rare. Herdsmen do not normally attempt pregnancy diagnosis. Yak cows are judged to be pregnant if they do not return on heat at the next expected oestrus period after mating. However, because a proportion of yak cows come on heat only once in a season, this negative way of assessing pregnancy has been found to lead to problems of unnecessary culling of cows that were thought to be barren but were, in fact, pregnant. There are no early visual indications of pregnancy, as there is no obvious outer swelling of the body in the early part of winter. An example of the mistaken culling of cows, because of lack of positive pregnancy diagnosis, was provided by an investigation by Cai Li, at Xiangdong Livestock Farm in Sichuan. Out of 38 yak cows that were culled in one year, 17 were found to be pregnant, and only 5 of them would have been culled anyway for other reasons. This mistaken culling, because of presumed barrenness reduces calf numbers and production from the herd. Cai Li found that rectal palpation would be an easy and quite accurate means of pregnancy diagnosis in yak under current methods of yak management (see also Chapter 5).

Calving

A yak female leaves the herd shortly before she is due to calve and seeks out a sheltered, low-lying place in which to deliver the calf. By the time the calf is born and she has licked it and it has started to suck, the herd has usually moved on. The calf is then in special danger from wolves and other predators, which are prevalent around the time of calving. The herdsman, therefore, has to pay extra attention from a distance to guard against such attacks, even when other assistance with calving is not required.

Assistance at calving

Yak cows graze all the year round but their nutrition is particularly poor in mid- and late pregnancy. They also have a somewhat shorter gestation length than Bos taurus cattle (see Chapter 5). As a consequence of both these factors, birth weights of pure yak calves are generally low and difficult labour is rare. Assistance at calving, therefore, is not normally required and would, in any case, be difficult to give, as yak cows are hard to approach during delivery because of their highly protective maternal instinct. However, assistance at birth is frequently necessary when a yak cow gives birth to an F1 (interspecies hybrid) calf. This is often too large for the cow to deliver unaided, especially when sires of large exotic breeds were used to produce the hybrid. Occasionally, a delivery by Caesarean section may be needed for a hybrid calf. Anaesthesia is provided by a method of electric acupuncture and local veterinary workers are readily trained in this technique. Such Caesarean delivery takes between one and two hours. The cow is conscious throughout, appears to suffer no pain and returns to normal activity immediately afterwards.

When calving is assisted, the navel cord is cut by knife. In all other cases the cord is broken during the act of the cow standing up after delivery or by the yak calf falling down. Although the broken cord is not sterilized, infections are rare.

Training of bulls for semen collection

When yak semen is required, most of the semen collection is from older bulls which are regarded as superior and because of a lack of information on the merits of young yak bulls. The training of adult bulls is therefore an important aspect of the process. The first step is for a herdsman, who knows the temperament of the particular bull to try by various means to overcome the bull's hostility. Training starts by holding the bull in a pen until it is used to being tied up and to being fed in a fixed place and, importantly, until the bull allows the herdsman to approach it. To become accepted by the bull in the pen, the herdsman will initially tempt the bull with grass and later stroke and scratch it from the front to the rear of the body and from the back to the abdomen.

The yak is most afraid of being touched on the head and, consequently, the herdsman avoids coming close to the head in the daily act of grooming. After some time, the herdsman will start to stroke the scrotum and testes of the bull and pull on its sheath and walk the haltered yak bull to its feed.

Training for semen collection follows by first getting the bull accustomed to a female in heat, while she is restrained in a crate and allowing him to mate her there. After that comes the process of guiding the sheath into an artificial vagina and allowing the bull to ejaculate into it. The temperature of the inner layer of the artificial vagina is kept between 39°C and 42°C. Eventually, a dummy cow can be used for the yak bull to mount, as happens with other types of cattle. However, a yak bull appears to be more sensitive to its surroundings, which therefore have to be kept quiet and familiar to the bull. Also, the bull has to be treated gently.

Castration of males

Males not selected for breeding are castrated. Most of this is done between the ages of one year and two and a half years. It is usual to do the castrations on a clear morning in early summer or late autumn, when the risk of infection to an open wound is reduced. First the young bull has to be caught in a pen and then put on his side for restraint. The lower part of the scrotum is sterilized with iodine and the bottom, held between thumb and index finger, cut off with a knife. The testicles are pushed out of the scrotum, the cords crushed and the wound sterilized with iodine solution and dusted with a powder to prevent infection. The scrotum is squeezed to close the cut end. The bull is then set free and walks away. The wound generally heals without complications within a week. The operation can take as little as ten seconds. With older bulls more care is required, particularly in handling the cord and sterilizing the wound.

In some areas a different technique is used. For example in the Ganzi area of Sichuan, the scrotum is slit vertically on the rear side, the testes are pushed out and totally removed. The other parts of the process are similar to those described.

Recently, a form of castration has come into use in which the testicles are pushed into the body cavity close to the belly. The upper part of the scrotum is then closed off with a rubber band to prevent the testicles slipping down again. The spermatozoa in the semen do not survive at the higher temperature inside the body. "Castration" is therefore achieved by physiological means and avoids the need for an operation. Moreover, the male will still secrete androgen after this treatment and, as a consequence, the growth rate will be greater than for the traditional steer and similar to that of an entire bull.

F1 hybrid bulls, although sterile are usually castrated at the age of one year to one and a half years.

A report by Feng and Su (1994) indicates that problems occasionally arise from the conventional form of castration. They record cases of strangulation of the small intestine by the free vas deferens, which is thought to have been excessively stretched during castration. The vas deferens was found to have wrapped itself around the small intestine as a result of strenuous movement on the part of the animal during work or other activity, when high abdominal pressure had forced a section of the intestine into the uro-genital fold that had previously been ripped open during castration. Once diagnosed, a simple operation rectified this problem in most cases.

Harvesting fibre

In China, shearing takes place usually once a year in May and June. In herds, shearing is done first on the pack yak (steers), then on the adult bulls and the replacement cows and finally on the adult cows. Animals with any skin disease have to be shorn separately from the rest. Parturient cows are shorn two weeks after calving and sick animals are shorn after they have recovered.

Cutting and plucking are alternatives to shearing. The down hair can be combed out prior to shearing. Prior to harvesting the fleece, the yak is taken into a pen and the legs tied. When shearing, which is the predominant method of harvesting the fleece, the long hair and the down are taken off together and are separated afterwards. The whole body is shorn but only a little is taken off the tail, as long tail hair may be used later.

The fleece can also be cut with a Tibetan knife, but the fibre remaining on the yak is longer than after shearing, and the total fleece yield and its down content are lower.

The plucking procedure involves grasping little groups of hair at a time, twining these around a wooden, mallet-shaped stick and pulling sharply. The yak jumps with pain at every pluck, but local people believe this promotes hair growth. The plucked hair contains little down and what is left behind may be gathered later or allowed to be shed.

With once-a-year harvesting (though tail hair is harvested once every two years), the content of down is low, irrespective of the method of harvesting used. The down hair felts readily and the quality is poor. With the increasing value of the down hairs for textiles, better methods of harvesting it are being popularized. Combing out the down with a wire comb, with teeth 1 cm distant and 10 cm long (Figure 8.9), provides a greater yield and better quality. Shearing then follows some time after the combing.

If down fibre is not to be lost, combing needs to start before the down begins to shed - which is about 20 days before the normal time for a single shearing.

Although such separate combing and shearing involves the yak being caught and restrained twice, and uses more labour, it can be economically efficient if the price for the fine down fibre is high enough. Machinery for combing is being developed to increase both the speed of harvesting and the yield of down.

Figure 8.9 Comb used for harvesting yak down

Management of yak in agricultural areas

In some yak areas of China, there is a relatively good microclimate and some parts of the land are suitable for cultivation. This occurs mostly in valleys at lower altitudes and near some streams in subalpine or agricultural-pastoral regions. The number of animals kept by a family is normally small and includes pure yak and F1 hybrids, with the latter often predominating in a mixed herd.

In northwest China such a herd will be kept in a backyard or a pen near the family abode. But in southwest China, such farmers have a permanent house, usually two or three storeys high. The upper floors are for the family and the ground floor serves as a pen for the animals - horses, cattle (including the yak), sheep, goats and pigs, all together. Usually there is no window to the pen, and a single gate provides access for both people and animals. A small courtyard often supplies the light and ventilation for the pen. The pen does not normally have a separate bedding area or feed trough, nor is there a special channel for collecting the dung. The animals move around freely and lie down where they wish. Farmers or herders frequently spread straw or leave straw chaff or weeds on the ground to keep the animals comfortable. The straw or waste is removed with the faeces in the spring and used as manure prior to cultivating the land. Sanitation in the pen is poor, but the animals keep warm, particularly in the enclosures used in northwest China.

During the warm season, the female yak and F1 hybrids are driven to the pastures, far from the farming area and are milked there. A few cows are retained in the pen at the homestead for milking and allowed to graze nearby during the day. During the cold season, all the animals are housed at night when they are given supplementary feed of straw and other crop by-products; during the day they graze stubble.

The use of yak and yak hybrids as draught and pack animals is of particular importance, although they are also used for milk and meat. The males - both pure yak and hybrids - kept for work are castrated and have nose rings inserted when a year old. They start to be trained for work from the age of two years and start working around the age of three or four years.

During the busy period of spring cultivation, the animals used for ploughing are given supplementary feed, including barley grain or peas. The animals plough for about eight to ten hours daily and receive their supplementary feed at every rest stop and at night (see Figure 8.10).

Figure 8.10 Yak bullocks ploughing in Yushu, Qinghai (Photo courtesy of Peter Horber)

A typical ploughing schedule
(for example, at the Tuobo township of Ganzi county in Sichuan) is as follows:

Hours:


0600 - 07.00

Give grass and access to water.

0700 - 0800

Allow rest in preparation for work.

0800 - 1000

Ploughing.

1000 - 1100

Rest (at ploughing site), give barley straw.

1100 - 1300

Ploughing.

1300 - 1500

Resting; supplementary feeding of grass and other feed, provide water.

1500 - 1700

Ploughing.

1700 - 1730

Short rest; give supplementary feed and grass

1730 - 1930

Ploughing.

1930 - 2000

Stop work and return to pen (or graze); provide water.

2000 - 0100

Provide grass and grain, and comb the animal.

0100 - 0600

Animals housed or allowed to graze outside.

During the busiest part of the season, ploughing may continue for ten hours a day and the return for feeding and rest in the evening may be delayed by a couple of hours. After the period of cultivation is over, the draught animals are driven to natural grazing and stay there until the winter, when they are housed. Some of the draught steers are used as pack animals, after a period of rest following the ploughing.

Both yak and F1 steers are used as pack animals. The animals work all the year round with little rest, apart from the autumn, when the grass is forming seed and the animals are allowed to graze and get fat. When working, the pack animals will walk continuously for seven to ten days and then rest for one or two days. The animals walk during daylight hours and graze and feed at night. A typical schedule is as follows:

0400 - 0600

Muster the pack animals from their grazing, saddle up and tie on loads. The drivers have their breakfast.

0600 - 0900

On journey (the loads may be re-arranged on the way).

0900 - 1030

Rest with loads; grazing allowed on adjacent pastures.

1030 - 1300

On journey.

1300 - 1400

Rest period without grazing.

1400 - 1700

On journey.

1700 - 1800

Stop for night, unload animals, let animals on to pastures for grazing, drinking water and resting until 04.00 the following morning, when the procedure is repeated.

Yak and the hybrid animals used for carrying loads are also used for riding (Figures 8.11 and 8.12), for which they may be saddled or not. They are not harnessed like horses; a nose rope is all that is required by the rider to control speed and direction. Yak are also used for work (Figure 8.13).

Figure 8.11 Pack yak (Both yak and hybrid steers are used) (Photo courtesy of D. Steane)

Figure 8.12 Riding (Both yak and hybrid animals are used)

Figure 8.13 Yak at work in Mongolia (Photo courtesy of Horst and Barbara Geilhausen)

References

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Feng D.G. & Su L. (1994). Small intestinal strangulation with deferent duct in 40 castrated Pianius. Proceedings of the first international congress on yak. Journal of Gansu Agricultural University (Special issue June 1994), pp. 327-330.

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Wiener G. (1996). Disasters waiting to happen - yak. Asian Livestock, XIX (8) 93-95

Winter, H. et al. (1992). Pyrrolizidine alkaloid poisoning of yaks (Bos grunniens) and confirmation by recovery of pylloric metabolites from formalin-fixed liver tissue. Research in Veterinary Science, 52, 187-194.

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Wang W.B. et al. (1997). Effect of concentrate supplement on yak body weight gain during grazing summer season. Proceedings of the second international congress on yak, in Xining, China, 1-6 September 1997. Xining, China, Qinghai People's Publishing House, pp. 135-136.

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