EFFECT OF METABOLISM MODIFIERS ON LIPID-METABOLISM IN THE PIG

Porcine somatotropin (pST) and certain beta-adrenergic agonists are po tent metabolic modifiers that can improve performance in pigs. Pigs tr eated with either compounds utilize feed more efficiently and are lean er than controls. Comparative slaughter data clearly demonstrate that pST and some beta-agonists stimulate protein deposition. Porcine somat otropin decreases lipid deposition, but this is not the case for all b eta-agonists. Somatotropin decreases lipid deposition through decreasi ng adipose tissue sensitivity to insulin, inhibiting lipogenesis, and perhaps stimulating lipolysis. Although lipolysis is increased during pST treatment of growing pigs, the greatest consequence is decreased l ipogenesis. Although under controlled conditions certain beta-agonists stimulate lipolysis and inhibit lipogenesis, the limited metabolic st udies suggest that at doses that are most efficacious for enhanced pro tein deposition, there are limited effects on lipid metabolism. In par t, this may be due to desensitization of adipose tissue beta-adrenergi c receptors and possibly a consequence of antagonism of beta-receptors .