Importance of Functional Ingredients in Yak Milk-Derived Food on Health of Tibetan Nomads Living Under High-Altitude Stress: A Review

Abstract

Tibetan nomads have lived since ancient times in the unique and harsh environment of the Qinghai-Tibetan Plateau with average altitudes over 4000 m. These people have been able to live and multiply healthily over numerous generations under the extreme stress of high-altitude environment, including cold, hypoxia, and strong ultraviolet radiation, and with a simple diet devoid of vegetables and fruits for most of the year. Their survival depends heavily on yak milk, and its products comprise the main portion of their daily diet. In this review, yak milk and its derived products are examined in detail and compared with milk from other ruminant species. Yak milk products seem to be particularly rich in functional and bioactive components, which may play a role in maintaining the health status of Tibetan nomads. This includes particular profiles of amino acids and fatty acids, and high levels of antioxidant vitamins, specific enzymes, and bacteria with probiotic activity (yoghurt is the main food). Based on that, it is proposed that the Tibetan nomads have developed a nutritional mechanism adapted to cope with the specific challenges posed by the environment of the world's highest plateau. Systematic studies are required to demonstrate this in a more mechanistic way.

First detection of neboviruses in yak (Bos grunniens) and identification of a novel neboviruses based on complete genome

“…Yak is a unique free-grazing bovine species in the Qinghai-Tibet Plateau (Ding et al, 2010;Guo et al, 2014). In this study, 22.0% (78/ 354) diarrhoeic samples of yak were detected as NeVs-positive by RT-PCR, and the virus was detected in 38 out of the 55 farms located across the three main yak-production areas in China, and the geographical distance between the two farthest NeVs positive farms is > 2000 km.…”

“…The yak (Bos grunniens) belong to the genus Bos within the family Bovidae and is a unique long-haired bovine species in the Qinghai-Tibet Plateau (Guo et al, 2014). There are over 14 million yaks in the world, which are distributed in high-altitude regions of China, India, Nepal, Pakistan, Kyrgyzstan, Mongolia and Russian Federation, and mainly distributed in the Qinghai-Tibet Plateau (above 3000-5000 m) in China (Mi et al, 2013).…”

“…There are over 14 million yaks in the world, which are distributed in high-altitude regions of China, India, Nepal, Pakistan, Kyrgyzstan, Mongolia and Russian Federation, and mainly distributed in the Qinghai-Tibet Plateau (above 3000-5000 m) in China (Mi et al, 2013). Yak is an essential animal of production and livelihood for local Tibetan people, providing meat, milk, skins, transport and fuel (faces) (Ding et al, 2010;Guo et al, 2014). Diarrhea is a common disease in yak, which cause serious economic losses (Chen et al, 2015;Gong et al, 2014).…”

The sustainable development of grassland-livestock systems on the Tibetan plateau: problems, strategies and prospects

“…The forage mass and nutritional content of wetland vegetation are high, and provide a suitable source of forage for livestock ). The higher feeding value of alpine wetland herbage, compared with that of other grassland, is thought to be a result of adaptation of metabolic processes to physiological stresses imposed by the cold temperatures and higher altitude of the wetlands (Guo et al 2014). The herbage mass of Kobresia tibetica (the dominant species of alpine wetland) is high, and may reach 768 kg DM ha -1 in August, sufficient to support 2.9 sheep units ha -1 for 1 year .…”

“…While a reduction in supply might otherwise increase per unit price due to scarcity, long-term security of income must be founded upon the production, promotion and marketing of high quality products, for which the consumer is prepared to pay a premium price. Over the previous 10 000 years, the indigenous animals (yak and Tibetan sheep) have evolved to survive the challenges imposed by the high altitude and cold environment of the Tibetan plateau regions, and are better able to digest the fibre contents of the native grasses and sedges compared with other exotic livestock breeds (Richmond et al 1977;Guo et al 2014). The yak is the most representative of livestock from these regions, and the unique features of its many products need to be publicised to develop a vibrant market (Ji 2001).…”