The biotechnological advances of recent years have put us on the brink of unprecedented gains in animal productivity. Manipulation of animal growth rate and composition of gain is now possible by a variety of techniques. Ex- amples include ingestion of beta-adrenergic agonists, injection of somatotropin, castration, immunization, and gene insertion. Animal Growth Regulation ad- dresses modem concepts of growth regulation with an emphasis on agricul- turally important animals. This emphasis is not exclusive, as many situations exist in which the only information available was generated in...