Tibetan Highland Yak

Tibetan Highland Yak

　　Origin and Distribution

　　Native to the highland grasslands of eastern Tibet Autonomous Region, with the best quality found in Jiali County. They are also distributed in the southwestern mountainous regions, inhabiting alpine and humid grasslands at elevations above 4,000 meters.

　　Physical Characteristics

　　Relatively large body size, compact build, long body with short legs, loose and thick hide but no dewlap. Back is flat, belly is large but not pendulous, narrow and sloping. Head is heavy, forehead is broad, face slightly concave. Most have horns that flare outward and upward. Eyes are round and bright. Tail is short and set low. Forelimbs are short and straight, hind limbs are knife-shaped with strong tendons and bones, and hooves are small and solid. Bulls have high and long withers, while cows have low and short withers that are also thin. The herd exhibits a mix of coat colors: 60% are entirely black, about 30% are black with white heads or faces, and the rest are gray, brown, or white. Long hair grows on the chest, belly, sides of the body, and upper thighs, with a soft, thick, and dense coat. This dense fur and well-developed subcutaneous connective tissue help the yaks survive in cold, high-altitude conditions. Adult bulls and cows weigh an average of 420.6 kg and 242.8 kg respectively, with heights of 130.0 cm and 107.0 cm.

　　Production Performance

　　Average birth weight: bulls 13.7 kg, cows 12.8 kg. Cows begin lactation in the second month after calving, with peak lactation occurring in July and August when pastures are lush. Average daily milk yield is 1.03 kg, with a butterfat content of 5.82%–7.49%. Meat production is also good; under grazing conditions, moderately fleshed adult castrated bulls weigh 379.1 kg, with a slaughter rate of 55%, a net meat rate of 46.8%, and a ribeye area of 50.6 cm². The yak is the only bovine breed that produces downy fiber. Hair can be sheared once a year, typically in June and July. Pregnant cows in late gestation and those with calves are only combed for down, not shorn.

　　Hair and down yields are 1.76 kg for bulls, 0.45 kg for cows, and 1.70 kg for castrated bulls. Skirt hair length ranges from 20–43 cm, and shoulder hair from 10–30 cm. The ratio of hair to down is 1:(1–2). In their native regions, yaks are seasonally estrous, with the breeding season from July to October, peaking from late July to early September. The estrous cycle lasts 17.8 days, with estrus lasting 16–56 hours. Both bulls and cows are first bred at around 3.5 years of age. The average gestation period is 255 days, with calving generally beginning in March. Calving interval is typically one calf every two years, and the reproduction survival rate is 48.2%. Yaks have strong teeth and flexible lips and tongues, giving them good foraging ability and adaptability to low-quality pastures. To improve yak performance, the Saishitang Ranch in Xinghai County, Qinghai Province (1999), conducted hybridization experiments between yaks and wild yaks, yielding noticeable results. At 12 months old, male hybrids with 1/4 wild yak blood were 3.96% taller, 7.60% longer in body, 7.06% wider in chest, 7.32% thicker in cannon bone, and 12.13% heavier than purebred yaks.

　　Zhou Minghai et al. of the Sichuan Grassland Research Institute (1998) proposed a new approach to three-way crossbreeding involving yaks—specifically Holstein cattle crossed with Tibetan yellow cattle and yaks. The resulting hybrids exhibit strong adaptability in high-altitude pastoral areas. At 2.5 years old, hybrid bulls and cows averaged 310.78 kg and 305.79 kg respectively, which is 126.48 kg and 149.92 kg heavier than same-aged pure yaks. Hybrid cows can be first bred between 2–3 years old and can be milked between 3–4 years old, about 1–2 years earlier than yaks. Their first lactation (183 days) yields 659.36 kg of milk, which is 2.65 times that of yak cows during the same period.