ORGAN WEIGHTS, MUSCLE COMPOSITION AND FATTY-ACID PROFILES IN LAMBS FED SALBUTAMOL - EFFECT OF A 5-DAY WITHDRAWAL PERIOD

Lambs were fed ad libitum on a diet containing the beta-adrenergic ago nist salbutamol (2 ppm) for 38 days to investigate its effects on orga n weights, muscle composition and fatty acid profiles. The influence o f a 5-day withdrawal period was also assessed. The oral administration of salbutamol did not increase muscle weights and no differences were found in liver, heart and lung proportions. However, kidney weight wa s higher in the salbutamol-not-withdrawn animals. In treated animals f at and collagen levels decreased (P < 0.05), while protein increased ( P < 0.05) in the semitendinosus (ST) muscle when compared to controls. However, no effects of the beta-agonist treatment were found in the l ongissimus dorsi (LD) muscle. Intramuscular LD polyunsaturated fatty a cids were higher (P < 0.05). Subcutaneous adipose tissue samples were higher (P < 0.05) in total unsaturated fatty acids and lower (P < 0.05 ) in total saturated fatty acids. All these changes in the fatty acid profiles of both intramuscular and adipose tissues were more marked af ter the 5-day salbutamol withdrawal period.