MANIPULATION OF LEAN DEPOSITION IN ANIMALS

Recent advances in technology have offered a variety of ways of enhanc ing the rate of lean deposition and reducing the rate of fat depositio n in livestock. Potentially, the orally active beta agonists offer a v ery attractive way of achieving this goal. These substances are analog ues of the hormone adrenalin. Despite the vast amount of work on the m ode of action of these compounds, it is not entirely clear how they wo rk. Although it appears that they have a direct effect upon adipose ti ssue, the situation in muscle is less clear. It has been difficult to demonstrate an effect of these materials on muscle cell in culture. Gr owth hormone injected into animals also reduces fat and increases lean . Unlike beta agonists, growth hormone increases the size of several o rgans of the body. Beta agonists appear to increase significantly only the weight of skeletal muscle; smaller increases in the weight of the intestines are also seen. If these treatments are to be used in pract ice it will be necessary to evaluate carefully their effect upon meat quality. At the time of writing they have not been approved for commer cial use.