Submitted to: International Society of Applied Ethology
Publication Type: Abstract only
Publication Acceptance Date: 5/10/2007
Publication Date: 7/30/2007
Citation: Poletto, R., Richert, B.T., Marchant Forde, J.N. 2007. Behavioral effects of “step-up” ractopamine feeding program on finishing pigs. In: (eds. F. galindo and L. Alvargez) Proceedings of the 41st International Congress of the International Society of Applied Ethology. p. 90. Interpretive Summary:
Technical Abstract: A better understanding of behavioral and neuroendocrine effects of ractopamine (RAC), a beta-adrenergic agonist widely used as swine feed additive, is needed to elucidate its impact on pig welfare. Our aim was to evaluate the effects of a “step-up” RAC feeding program on the behavior of finishing pigs. Thirty two pigs (16 barrows and 16 gilts) were assigned to pens of four (by gender), as either control (CTR) or RAC treatment. Treated animals were fed RAC at 5ppm for 2 weeks, then 10ppm for two more weeks until slaughter. The dominant and subordinate pigs in each pen were determined at assignment by continuous behavior observation (36h). Behavior was also continuously recorded for 24h on the day before dietary treatment (Phase I), four days during RAC 5ppm (Phase II), and four days during RAC 10ppm (Phase III). Ten-minute scan sampling was used to define time-budgets. Repeated mixed models were used to analyze behavioral data, presented as average percentages of total time. In general, RAC fed pigs spent less time inactive (73.73 vs.77.86±0.07; p<0.05) and more time alert (3.65 vs. 1.55±0.03; p<0.01); however, there were phase by treatment interactions for these behaviors (p<0.05). Time spent bar biting (0.28 vs. 0.12±0.002; p<0.01) and sham-chewing (2.35 vs. 1.64±0.01; p<0.05), in addition to time spent sitting (1.50 vs. 0.42±0.02; p<0.05), were also greater in RAC fed pigs compared to CTR. Initiated non-aggressive social behavior tended to be higher in subordinate compared to dominant pigs (2.41 vs. 1.47±0.02; p=0.07), whereas engagement in agonistic interactions was higher in RAC pigs (treatment by phase; p<0.05) and subordinate gilts (gender by rank; p<0.05). Higher activity of RAC pigs may lead to increased aggression in the home pen, and greater incidence of oral-related behaviors proposed as stereotypic may be related to neuroendocrine effects of the compound, potentially disrupting finishing pigs’ welfare.