section_path: Characteristics/Reproduction
section_name: Reproduction
paragraph_text: Reproduction
  
  The gestation period for a cow is about nine months long. The ratio of male to female offspring at birth is approximately 52:48. A cow's udder has two pairs of mammary glands or teats. Farms often use artificial insemination, the artificial deposition of semen in the female's genital tract; this allows farmers to choose from a wide range of bulls to breed their cattle. Estrus too may be artificially induced to facilitate the process. Copulation lasts several seconds and consists of a single pelvic thrust.
  
  Cows seek secluded areas for calving. Semi-wild Highland cattle heifers first give birth at 2 or 3 years of age, and the timing of birth is synchronized with increases in natural food quality. Average calving interval is 391 days, and calving mortality within the first year of life is 5%. Beef calves suckle an average of 5 times per day, spending some 46 minutes suckling. There is a diurnal rhythm in suckling, peaking at roughly 6am, 11:30am, and 7pm. Under natural conditions, calves stay with their mother until weaning at 8 to 11 months. Heifer and bull calves are equally attached to their mothers in the first few months of life.