Milking performance of China yak (Bos grunniens): A preliminary report

Yak milk plays a very important role in Tibetan's daily life. Milk and milk products are the major dietary ingredients as well as family incomes of Tibetan herders in China. Yak milk yield and composition are seasonal and affected by the breed, age, parity and body condition of cow, pasture growth and quality, milking time, milking methods and environmental factors. In this paper, milk production and composition of different breeds are documented, and effects of feeding level, milking time, milking method, environmental factors on milking performance are discussed. It is found that Batang yak from Qinghai Province peaks and Jiali yak from Tibet Autonomous Region bottoms milk production, with 487.2 and 147.6 kg fresh milk per lactation respectively. Comparatively, milk of Jiulong yak and Sibu yak has higher dry matter and fat contents, and milk of Tianzhu White yak contains more protein and lactose. Winter supplementation on dams can improve calf production and milk yield of mother yaks in the following warm season. Compared with once-a-day milking, twice-a-day milking stimulates yak female to give about one third more milk, which, however negatively affect the growth of calves. Yak produces less milk at too high temperature with strong solar radiation on clear days, but more milk within short periods of cloudy or rainy time.