Location: Livestock Behavior ResearchTitle: Effects of social isolation and environmental enrichment on laboratory housed pigs Author
Submitted to: International Society of Applied Ethology
Publication Type: Abstract Only
Publication Acceptance Date: 4/4/2012
Publication Date: 7/31/2012
Citation: Deboer, S.P., Garner, J.P., Eicher, S.D., Lay Jr, D.C., Marchant Forde, J.N. 2012. Effects of social isolation and environmental enrichment on laboratory housed pigs. International Society of Applied Ethology. Proceedings ISAE. Interpretive Summary:
Technical Abstract: The pig is becoming an increasingly important laboratory animal species. However, a laboratory setting often requires individual and sterile housing, which may impose stress. The objective of this study was to determine physiological, haematological and behavioral effects of isolation and environmental enrichment in pigs housed for 7 days within the PigTurn™ - a novel penning system with automated blood sampling capability. Sixteen castrated male (7) and female (9) (Yorkshire × Landrace) commercial weaner pigs were randomly assigned to one of four treatments in a 2 x 2 factorial combination of enrichment (non-enriched or enriched with a mirror and rubber mat) and isolation (visually isolated or able to see another PigTurn and pig). Pigs underwent catheterization surgery and were placed into the PigTurns 24h post-recovery. They were fed each morning and had ad libitum access to water. Blood samples were collected automatically twice a day at 0900 and 1300 h. The morning sample was assayed for plasma concentrations of cortisol and TNF-a, whereas the afternoon sample was used to determine WBC differentials. Behavior was video-recorded between 0600 and 1800 h and sampled using instantaneous 10-minute scans, to determine time budgets. Data were analyzed as a repeated measures mixed model (REML) using the MIXED procedure of SAS. TNF-a was not affected by treatment. However, pigs housed in enriched pens had lower plasma cortisol concentrations (1.3±0.1 µg/dL) than those in non-enriched pens (1.8±0.2 µg/dL, P<0.05). There was also significant isolation*enrichment interaction. Enrichment given to pigs housed in isolation had no effect on plasma cortisol (1.5±0.2 and 1.5±0.2 µg/dL), but greatly reduced it in pigs able to see another pig (1.1±0.2 and 2.2±0.2 µg/dL). Eosinophil count also differed between treatments, being highest in the enriched/not isolated treatment (0.6±0.1 K µL) and lowest in the not enriched/isolated treatment (0.2±0.1 K µL, P<0.05), with the other treatments intermediate. Enrichment tended to increase time spent standing and lying laterally (P<0.1). The results suggest that being able to see another animal but not interact resulted in elevated plasma cortisol concentrations. High cortisol may then also impact eosinophil numbers, by known effects on generation, survival and function. However, appropriate enrichment can improve these measures.