Calves mainly use excellent beef cattle such as Simmental, Charolais and Limousin as male parents, and Luxi yellow cattle as female parents for cross improvement. Its hybrid offspring generally have the characteristics of roughage tolerance, strong adaptability and fast growth, and the birth weight, daily gain, pulling power, meat quality and slaughter rate have all been significantly improved, showing good hybrid advantages.

With regard to the origin of other cattle breeds, Keller (1909) once thought that bos frontalis was domesticated by Javanese bison. However, according to the research on the types and angles of skulls in modern times, and the analysis that the hybrid between tumor cattle and ordinary cattle can produce offspring and breed new varieties, it is proved that tumor cattle also originated from the original cattle, and its domestication time in South Asia is roughly the same as or a little later than that of ordinary cattle. The characteristics of the "cow" recorded in China ancient books, that is, the modern buffalo China Buffalo, are very similar to the Indian wild buffalo in terms of coat color, skull and horn shape. Therefore, scholars previously believed that China buffalo originated from the Indian wild boxer cow-Bubalius Arn. However, recent studies on the fossils of at least 7 species of buffalo unearthed in different stages of the Pleistocene in North China, Northeast China, Inner Mongolia, Sichuan and other places have proved that at least 1 ~ 2 of them have evolved into modern domestic buffaloes. China buffalo originated in the south. This may be due to the glacier attack in northern Asia in the late Pleistocene, which made the vast area north of the Yellow River basin in the past tropical, dry and cold, and forced the ancient buffalo and other animals to migrate to the south. China yak is domesticated from wild yak. Up to now, wild yaks are still distributed in Haibei, Qinghai Province, the alpine region of Hainan, the mountains with an altitude of 4 000 ~ 5 000 meters in the northern part of the Qinghai-Tibet Plateau, and the northeastern part of Siberia in Mongolia and the Soviet Union.

It varies according to different cattle breeds (genera). There are 32 teeth, including 8 incisors, 24 upper and lower molars and no canine teeth. There are no front teeth in the upper jaw, only dental pads. The stomach is divided into four chambers: rumen, reticulum, flap stomach and abomasum, of which rumen is the largest. Meditate. The hoof was split in half. The nasal endoscope is smooth and moist. If it is dry, it is a sign of illness. The rate of singleton twins is only 1 ~ 2.3%. Except that yaks in alpine regions are in seasonal estrus due to perennial grazing and climate influence, cows kept in houses are generally in estrus for many times all the year round. The estrus cycle is basically the same, with an average of about 2 1 day.

I've never had a cow. I don't know.