ABSTRACT
This chapter presents a capital theory model of herders' decisions concerning the age at which they sell animals. Age of sale is a key variable for determining herd size, age/sex composition, animal productivity, and offtake. Value is taken as including cash receipts, the implicit value of animal products consumed by the pastoral family, the value of progeny, liquidity, security, prestige, power, and so forth. The rate of weight gain is a function of the animal's age, and is high at early ages, but slows down when the animal is older. An improvement of production conditions that uniformly increases the rate of weight gain at all ages will tend to increase the age of sale since animals will have higher rates of gain at all ages including at older ages. The present value calculations, along with the assumption of an optimizing pastoralist, yield predicted age of sale and herd dynamics.
