🐃 Yak

The yak (Bos grunniens) is a domestic bovine of Asia's highlands, able to withstand frosts down to −40 °C and thin mountain air. FAO estimates there are about 14 million yaks in the world, more than 90% of them in China, and their heartland is the Qinghai-Tibet Plateau. Yaks usually live at altitudes of 2000–5000 m and are also found in Mongolia, Nepal, Bhutan and northern India.

A female yak gives 150–500 litres of milk per lactation, usually 1–3 kg a day. Lactation is seasonal: most milk comes in summer on fresh pastures, while in winter it is just 2–4 litres a month, yet the cow is often not dried off and keeps milking into the next year. She lets down her milk only when her calf is nearby. There are no specialised dairy breeds, but yak–cattle crosses, the dzo, called chauri in Nepal, give more milk.

Yak milk is thick and sweetish: 5.5–7% fat, 16–18% total solids, and more protein and lactose than cow's milk. Its most important product is butter: it goes into tea and tsampa and is burned in lamps. People also make hard dried cheeses such as chhurpi and Tibetan qula, as well as clarified butter. A protein specific to yak milk has been found in bronze cauldrons of Mongolian nomads about 2700 years old, one of the earliest traces of such milk.

Why it matters to you. Raw yak milk often has poor hygiene indicators, so in the mountains it is boiled before use; do the same if you taste it while travelling. Butter and dried cheese keep for a long time: butter in a skin bag lasts up to a year or two.