Submitted to: International Society of Applied Ethology
Publication Type: Abstract Only
Publication Acceptance Date: 4/24/2002
Publication Date: 8/7/2002
Citation: MARCHANT FORDE, J.N., LAY JR, D.C., RICHERT, B.T., SCHINCKEL, A.P., PAJOR, E.A. THE EFFECTS OF RACTOPAMINE - A BETA ADRENERGIC AGONIST - ON BEHAVIOR, HEART RATE AND STRESS HORMONES OF FINISHING PIGS. INTERNATIONAL SOCIETY OF APPLIED ETHOLOGY. 2002. Interpretive Summary:
Technical Abstract: Ractopamine - a beta-adrenergic agonist - is fed to slaughter pigs in the US and acts as a repartitioning agent, promoting lean tissue deposition. However, there are anecdotal reports of adverse effects on the pigs' behaviour. This study aimed to investigate the effects of ractopamine (RAC) on behaviour and physiology of pigs during handling and transport. Twenty-four groups of 3 finishing pigs were assigned to one of two treatments, four weeks prior to slaughter; 1) finishing feed plus RAC (9 ppm), 2) finishing feed alone. Behavioral time budgets were determined over a single 24-hour period during each week. Behavioral responses to routine handling and weighing were determined at the start of the trial and at the end of each week. Heart-rate responses to unfamiliar human presence were measured and blood samples were taken from a single pig in each pen on different days during week 4. At the end of week 4, pigs were transported to slaughter. Heart rate was recorded during transport and a further post-slaughter blood sample was taken from those pigs that were previously sampled. During the weeks 1 and 2, RAC pigs were more active (p<0.05), more alert (p<0.05) and spent less time lying laterally (p<0.05). Initially, there were no differences in responses to handling. However, over each of the next 4 weeks, RAC pigs were more difficult to get out of the home pen and into the weigher. At the end of week 4, RAC pigs had higher heart rates in the presence of an unfamiliar human (p<0.05) and during transport (p<0.05) and had higher circulating epinephrine (p<0.05) and norepinephrine (p<0.01) concentrations. The results show that ractopamine does affect the behavior, heart rate and catecholamine profile of finishing pigs and making them more difficult to handle and potentially more susceptible to handling and transport stress.