Lipolytic responses to catecholamines in ractopamine-treated pigs

Abstract

The β-agonist ractopamine (RAC) promotes protein deposition with little effect on fat deposition in the pig. To assess whether the lack of effect on fat deposition was due to changes in response to catecholamines, crossbred pigs with venous catheters were used to examine plasma non-esterified fatty acid (NEFA) concentrations before and after intravenous (i.v.) injections of the (β1+β2)-agonist isoproterenol and the β2-agonist fenoterol during dietary RAC (0 or 20 mg/kg) treatment. In Expt 1, gilts received increasing i.v. doses of fenoterol [3, 9, 27, 81, and 243 μg/kg bodyweight (BW)] on Day 34 and blood samples were taken for metabolite analyses. The protocol was repeated on Day 36 but thi..