THE EFFECT OF RACTOPAMINE ON PERFORMANCE, CARCASS COMPOSITION AND MEAT QUALITY OF FINISHING PIGS

Abstract

One hundred and twenty-eight purebred Lacombe pigs (equal numbers of barrows and gilts) were assigned to one of four treatments at 64 kg and fed a commercial grower-finisher diet ad libitum to which ractopamine (RAC) was incorporated (0 mg kg−1, 10 mg kg−1, 15 mg kg−1, or 20 mg kg−1). Pigs were slaughtered at 100 kg. RAC had no significant effect on growth rate, feed intake, feed efficiency or on days on feed. Predicted lean content obtained by the Hennessy Grade Probe regression equation (from fat and muscle depth) increased by 0.3%, 0.7% and 0.9%, respectively (P = 0.009) as RAC was added to the diet at 10, 15 and 20 mg kg−. Dissected lean yield, as measured by separation of four primal cuts into lean, bone and fat depots, increased by 1.9%, 2.3% and 3.2%, respectively (P = 0.001) for the same levels of RAC. Greatest muscle increases were found in the ham (10.7%). There was a clear anterior to posterior gradient for fat reduction in both the subcutaneous (Picnic 13.4%, Butt 13.5%, Loin 10.7%, Ham 8.2%) and intermuscular (Picnic 16.2%, Butt 13.7%, Loin 8.8%, Ham 5.3%) fat depots. RAC increased intramuscular fat content (P = 0.009), expressible juice (P = 0.001), shear value (P = 0.011) and decreased fat hardness (P = 0.026). Based on the results of this study, RAC would be expected to have minor effects on swine growth performance and meat quality, but would increase the lean content of the carcass. Key words: Swine, ractopamine, carcass composition, meat quality