Future developments in the manipulation of growth in farm animals.

The anabolic steroid and antimicrobial growth promoters may be regarded as the first generation of animal growth promoters or performance enhancers. There is major investment in the development of new techniques to improve the efficiency of farm animal production. These techniques are reviewed under the headings of growth hormone (somatotrophin) and related techniques, immunological techniques, the beta-adrenergic agonists and the direct genetic manipulation of farm animals.