Farm Animals, Age of

important criterion of the economic value of an animal. The growth of an animal begins from the embryonic or uterine period, the average length of which is constant for each animal species. In postembryonic, or postuterine, growth several age periods are distinguished.

The period of the newly born usually lasts for several days and is characterized by the fact that, being nourished by colostrum, the animal adapts itself to life outside the mother’s womb within a brief period of time. The milk period continues until the animal is weaned from its mother, or until it is stopped being fed milk. In colts the milk period lasts up to 6-8 months; in calves, up to 5-6 months; in lambs, up to 3½–4 months; and in baby pigs, up to two months. The period of sexual maturation is characterized by incipient functioning of the reproductive organs. During this period the basic individual and species traits of animals take shape. Sexual maturity is attained by horses at the age of 12-18 months (sometimes earlier); cattle, 6-10 months; sheep, 6-8 months; and pigs, 4—6 months. An animal reaches sexual maturity before the organism has attained its final shape, and therefore farm animals are mated somewhat later. The period of maturity is characterized by a flourishing of the organism’s functional activity; during this period the reproductive capacity and productivity of animals reaches its maximum development. In horses the period of maturity lasts from seven to 15 years; in cattle, from five to 10-12 years; in sheep, from four to 6-7 years; and in pigs, from two to 5-6 years. This is the most important period for the economic utilization of animals, and it may be prolonged by proper feeding, good care, and proper usage. During the period of growing old the vital processes in the organism gradually slow down; the animals’ reproductive capacity and productivity decrease markedly, and the animal’s economic utilization comes to an end. The age limits for the use of horses are 18-20 years; camels, 15-20 years; cattle, 15-16 years; sheep, 7-8 years; goats, 6-8 years; pigs, 6-7 years; rabbits, 5-6 years; geese, 5-7 years; and ducks and turkeys, 3-4 years. The age of farm animals is determined on the basis of exact registration of their births and by the branding of farm animals. When necessary, the age of animals may be determined by their teeth (in horses, cattle, pigs, and sheep), in birds by their feathers, and in fish by their scales.