The effects of ractopamine on the behavior and physiology of finishing pigs12

Abstract

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.

Nutrition-induced differences in body composition, compensatory growth and endocrine status in growing pigs ,

“…Plasma concentration of cortisol was determined using a competitive binding radioimmunoassay kit (Marchant-Forde et al, 2003;GammaCoat, DiaSorin, Stillwater, MN, USA). A Multi Species Leptin Ria kit (Cat.…”

The effect of ractopamine supplementation at 5 ppm of swine finishing diets on growth performance, carcass composition and ultimate pork quality

“…In this size of experiment, it is difficult to conclude that these DOAs and condemns were due to the RAC, or were a random effect; however, since we have no way of excluding these animals based on treatment, they are assumed to be due to the RAC treatment. Previous research suggests that RAC pigs may be more susceptible to stress during shipping (Marchant-Forde et al 2003). This particular experiment was carried out at PSC Elstow Research Farm, which is located less than 1 h travel time from the abattoir.…”

Metabolic and behavioral effects of ractopamine at continuous low levels in rats under stress

“…Studies with low doses of RAC over increasing periods are scarce. Moreover, production animals are constantly submitted both to chronic stress by confinement and handling, such as acute stress by transport and slaughter (Marchant-Forde et al 2003), which could make the results of this study important. Information regarding the potential use of RAC on metabolic parameters has been highlighted in several studies, but information about the behavior is still infrequent.…”

“…Information regarding the potential use of RAC on metabolic parameters has been highlighted in several studies, but information about the behavior is still infrequent. Studies with pigs fed with RAC demonstrated changes in pig's behavior (Marchant-Forde et al 2003;Poletto et al 2010). Other studies have demonstrated the influence of beta-adrenergic agonists on rodent's behavior (Flicker and Geyer 1982;Gorman and Dunn 1993).…”