Marchant-Forde J N, Lay D C, Pajor E A, Richert B T, Schinckel A P
Department of Animal Sciences, Purdue University, West Lafayette, IN 47907, USA.
J Anim Sci. 2003 Feb;81(2):416-22. doi: 10.2527/2003.812416x.
The objectives of this study were to examine the effects of ractopamine (RAC) on the behavior and physiology of pigs during handling and transport. Twenty-four groups of three gilts were randomly assigned to one of two treatments 4 wk before slaughter: finishing feed plus RAC (10 ppm) or finishing feed alone. Pigs were housed in the same building in adjacent pens with fully slatted floors and ad libitum access to feed and water. Behavioral time budgets were determined in six pens per treatment over a single 24-h 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 wk 4. At the end of wk 4, all pigs were transported for 22 min to processing. Heart rate was recorded from at least one pig per pen during transport and a postmortem blood sample was taken from those pigs that were previously sampled. During wk 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 wk 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 wk, fewer RAC pigs exited the home pen voluntarily, they took longer to remove 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 wk 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 wk 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 affected behavior, heart rate, and catecholamine profile of finishing pigs and made them more difficult to handle and potentially more susceptible to handling and transport stress.
本研究的目的是检验莱克多巴胺（RAC）对猪在处理和运输过程中的行为及生理的影响。在屠宰前4周，将24组每组3头后备母猪随机分配到两种处理方式之一：育肥饲料加RAC（10 ppm）或仅喂育肥饲料。猪被饲养在同一栋楼相邻的栏舍中，栏舍地面为全漏缝地板，可自由采食和饮水。在每周的单个24小时时间段内，对每种处理方式的6个栏舍中的猪进行行为时间预算测定。在试验开始时和每周结束时，测定这些猪对常规处理和称重的行为反应。测量所有猪对陌生人类出现的心率反应，并在第4周的不同日期从每个栏舍的一头猪采集血样。在第4周结束时，将所有猪运输22分钟至加工厂。运输过程中记录每个栏舍至少一头猪的心率，并从之前采样的猪中采集宰后血样。在第1周和第2周，饲喂RAC的猪活动时间更多（P < 0.05），警觉时间更多（P < 0.05），侧卧时间更少（P < 0.05）。它们在第1周在采食器处停留的时间也更多（P < 0.05）。在试验开始时，对处理的行为反应没有差异。然而，在接下来的4周中，饲喂RAC的猪中自愿离开栏舍的更少，将它们从栏舍中赶出所需时间更长，赶入秤上所需时间更长，并且需要饲养员更多的轻拍、掌掴和推搡才能进入秤台。在第4周结束时，饲喂RAC的猪在有陌生人类在场时（P < 0.05）和运输过程中（P < 0.05）心率更高，但在装卸过程中不是这样。同样在第4周结束时，饲喂RAC的猪循环儿茶酚胺浓度高于对照猪（P < 0.05）。处理方式之间循环皮质醇浓度以及皮质醇对运输的反应没有差异。结果表明，莱克多巴胺影响育肥猪的行为、心率和儿茶酚胺水平，使它们更难处理，并且可能更容易受到处理和运输应激的影响。
