About Bos taurus Linnaeus, 1758
Cattle (Bos taurus Linnaeus, 1758) are large artiodactyl mammals with cloven hooves, meaning they walk on two toes: the third and fourth digits. Like all species in the bovid family, cattle can have unbranched horns that are not shed every year. Their coat color varies by breed; common colors include black, white, and red/brown, and some breeds have spotted or mixed coat patterns. Among cattle of the same breed, bulls are larger than cows, differing in weight by up to several hundred kilograms. For example, British Hereford cows weigh 600–800 kg (1,300–1,800 lb), while Hereford bulls weigh 1,000–1,200 kg (2,200–2,600 lb). Before 1790, the average net weight of beef cattle was only 160 kg (350 lb), and weights have increased steadily since that time. Cattle breeds vary widely in overall size; the tallest and heaviest breed is the Chianina, where a mature bull can reach up to 1.8 m (5 ft 11 in) at the shoulder and up to 1,280 kg (2,820 lb) in body weight. The natural lifespan of domestic cattle is 25 to 30 years. In farming practice, beef cattle are typically sent to slaughter around 18 months of age, and dairy cows are slaughtered at around five years old. For reproduction, the gestation period of a cow is approximately nine months long. The birth ratio of male to female offspring is roughly 52:48. A cow's udder has two pairs of mammary glands (teats). Cattle farms often use artificial insemination, which involves depositing semen into the female's genital tract artificially. This practice allows farmers to select bulls from a wide range of options for breeding. Estrus may also be artificially induced to make the breeding process easier. Natural copulation in cattle lasts several seconds and consists of a single pelvic thrust. Cows seek out secluded areas to give birth. Semi-wild Highland cattle heifers have their first calf at 2 or 3 years of age, and birth timing is synchronized with seasonal increases in natural food quality. The average calving interval is 391 days, and 5% of calves die within the first year of life. Beef calves suckle an average of five times per day, spending a total of 46 minutes suckling daily. Suckling follows a diurnal rhythm, with activity peaking at roughly 6am, 11:30am, and 7pm. Under natural conditions, calves stay with their mother until weaning, which occurs between 8 and 11 months of age. Heifer and bull calves are equally attached to their mothers during the first few months of life. Regarding environmental impacts, the gut flora of cattle produce methane, a potent greenhouse gas, as a byproduct of enteric fermentation. Each cow releases roughly 100kg of methane per year via belching. Additional methane is produced by the anaerobic fermentation of stored cattle manure. The Food and Agriculture Organization estimates that cattle farming contributed around 7% of global greenhouse gas emissions in 2015. Quickly reducing these methane emissions helps limit climate change. Concentrated animal feeding operations, in particular, produce large volumes of wastewater and manure that can cause multiple environmental harms, including soil erosion, human and animal exposure to toxic chemicals, the development of antibiotic-resistant bacteria, and increased E. coli contamination. In many regions around the world, overgrazing by cattle has reduced biodiversity of native grazed plants and animal species at multiple trophic levels in affected ecosystems. A well-documented outcome of overgrazing is woody plant encroachment in rangelands, which significantly reduces the land's carrying capacity over time.
