PASSIVE-IMMUNIZATION OF INSULIN-LIKE GROWTH-FACTOR (IGF)-1 AND OF IGF-1 AND IGF-2 IN CHICKENS

The effects of passive immunization against IGF-1 either alone, or tog ether with immunization against IGF-2, on growth and metabolism were e xamined in chickens, Immunization against IGF-1 alone had no effect up on any aspect of growth, carcass composition, efficiency of energy uti lization or hormone concentrations studied, Immunization against both IGF-1 and IGF-2 together resulted in a lighter final body weight (P < 0.05) compared with controls, Immunization against both IGFs together decreased abdominal fat content (P < 0.05) and resulted in a heavier m ean spleen weight (P < 0.01), The joint immunization was also associat ed with elevated plasma T-3 concentrations, These data may indicate a role for IGF-2, but not for IGF-1, in fat metabolism in chickens.