Long-hair fur forehead yak (རིང་པོ སྐྲ སྤུ དཔྲལ་བ། འབྲོང)
According to the (Chinese) Provincial annals of livestock breeds, there are 12 officially recognized breeds of domestic yak in China: the Jiulong yak and Maiwa yak in Sichuan, Tianzhu White yak and Gannan yak in Gansu, Pali yak, Jiali ("Alpine") yak and Sibu yak in Tibet, Huanhu yak and Plateau yak in Qinghai, Bazhou yak in Xinjiang and Zhongdian yak in Yunnan, and one other, the "Long-hair-forehead yak" in Qinghai - which does not, however, meet all the criteria used to define a yak breed. Among these, the Plateau yak, Maiwa yak, Jiulong yak, Tianzhu White yak and Jiali ("Alpine") yak are also included in the publication Bovine breeds in China.
While their domesticated counterparts can be found in a much more varied area in the oriental region, the main geographic range of wild B. grunniens is limited to the Tibetan Plateau, which includes "...the western edge of Gansu Province, Qinghai Province, the southern rim of the Xinjiang Autonomous Region, and the Tibet Autonomous Region." (Schaller & Wulin, 1995).
The yak of the Qinghai-Tibetan Plateau yak (often called Plateau or Grassland yak) and those of the Henduan mountain Alpine yak (often called Alpine or Valley yak) have long been regarded as "types". This classification was initially based on the geographic and topographic parameters of their habitats and on the body size of different yak populations in the different environments. Although there are some differences between the main types in appearance and in aspects of their performance - as there are also among the breeds - it is not yet resolved to what extent such differences are genetic and to what extent they derive from varying conditions in the areas in which these yak populations are found.
Schaller and Liu (1996) estimated 8,000–8,500 Wild Yaks in Tibet, of which about 7,000–7,500 were in the Chang Tang Reserve (284,000 km²), plus about 3,200–3,700 in Qinghai Province, and about 2,000–2,500 in Xinjiang. These figures were, of necessity, a combination of estimates and inferences, but they suggest that the world population of Wild Yak was probably about 15,000 in 1995 (Miller et al. 1994, Schaller 1998). However, the population trend has been downward in many areas: Wild Yak in the southern 24% of Chang Tang have been almost exterminated with the arrival of herders since the 1960s. In the last IUCN Red List assessment, Harris and Leslie (2008) estimated the population for Wild Yak at no more than 10,000 mature individuals, and this is still likely.
Wild Yaks live in the alpine tundra, grasslands, and cold desert regions of the northern Tibetan plateau (Wiener et al. 2003). These mountainous areas range from 4,000 to 6,100 m elevation. In the Chang Tang Reserve in northwestern Tibet, the average annual precipitation is only 100–300 mm, much of it falling as hail and snow; lakes are generally saline and surface water is scarce. Temperatures can fall below -40°C. Vegetation is sparse, and is dominated by grasses, sedges, forbs, and low or procumbent shrubs; much of it can be classed as alpine, or high cold steppe (Schaller and Gu 1994). The species moves seasonally, descending into lower valleys in the winter (Miller et al. 1994, Smith and Xie 2008). It feeds mostly on grasses and sedges, with some forbs. Yaks are gregarious, often aggregating into groups of >100 individuals, although smaller groups of 10-20 are also common. Adult males often travel with females and young, although older males will often travel alone or form small groups of 2-5. Male herds range mostly at lower altitudes and in less rugged topography than females (Berger et al. 2014).
Wild yaks are larger, the bulls standing up to 2 metres tall at the shoulder and weighing over 800 kg (1,800 pounds); cows weigh less than half as much. In China, where they are known as “hairy cattle,” yaks are heavily fringed with long black hair over a shorter blackish or brown undercoat that can keep them warm to –40 °C (−40 °F). Colour in domesticated yaks is more variable, and white splotches are common. Like bison (genus Bison), the head droops before high massive shoulders; horns are 80 cm (30 inches) long in the males, 50 cm in females.
Red Blood Cells
Yaks’ lung capacity is about three times that of cattle, and they have more and smaller red blood cells, improving the blood’s ability to transport oxygen.
The yak in the Himalayas are adapted rather than acclimatezed to the low oxygen partial pressures of high altitudes. Their hemoglobin has a high oxygen affinity, so that full saturateon of the blood with oxygen occurs at a lower partial pressure of oxygen.