The earliest beasts of burden were oxen, the number of oxen usually equalled the number of cows. If there were not enough oxen, an ox was yoked together with a cow. Besides beasts of burden (oxen and horses), the herd of a farm usually included cows and heifers, a colt or a filly, two or three sheep, goats, pigs and poultry. Pigs were kept for meat, sheep for wool and making sheepskin coats.