Submitted to: Trends in Agricultural Science
Publication Type: Proceedings
Publication Acceptance Date: 5/27/2003
Publication Date: 5/27/2003
Citation: MARCHANT FORDE, J.N., LAY JR, D.C., PAJOR, E.A., RICHERT, B.T., SCHINICKEL, A.P. ASSESSING ANIMAL WELFARE: SPECIFIC RESEARCH APPROACHES. THE EFFECTS OF RACTOPAMINE ON BEHAVIOR AND PHYSIOLOGY OF FINISHING PIGS. TRENDS IN AGRICULTURAL SCIENCE. 2003. P. 19. Interpretive Summary:
Technical Abstract: The objectives of this study were to examine the effects of ractopamine (RAC) on behavior and physiology of pigs during handling and transport. Twenty-four groups of 3 gilts were randomly assigned to one of two treatments, four weeks prior to slaughter; 1) finishing feed plus RAC (10 ppm), 2) finishing feed alone. Pigs were housed in the same building in adjacent pens, with fully slatted floors and access to feed and water ad libitum. Behavioral time budgets were determined in 6 pens per treatment over a single 24-hour period during each week. Behavioral responses of these pigs 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 in all pigs and blood samples were taken from a single pig in each pen on different days during week 4. At the end of week 4, all pigs were transported for 22 minutes to processing. Heart rate was recorded from at least one pig per pen during transport and a further post-mortem blood sample was taken from those pigs that were previously sampled. During weeks 1 and 2, RAC pigs spent more time active (P<0.05), more time alert (P<0.05) and less time lying in lateral recumbency (P<0.05). They also spent more time at the feeder in week 1 (P<0.05). At the start of the trial, there were no differences in behavioral responses to handling. However, over each of the next 4 weeks, fewer RAC pigs exited the home pen voluntarily, they took longer to move from the home pen, longer to handle into the weighing scale and needed more pats, slaps and pushes from the handler to enter the scales. 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), but not during loading and unloading. Also at the end of week 4, RAC pigs had higher circulating catecholamine concentrations (P<0.05) than control pigs. Circulating cortisol concentrations and cortisol responses to transport did not differ between treatments. 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.