|DEBOER, SHELLY - Purdue University
|GARNER, JOSEPH - Purdue University
|MCCAIN, ROBYN - Purdue University
|Lay Jr, Donald
Submitted to: Animal Welfare
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/29/2014
Publication Date: 2/1/2015
Citation: Deboer, S.P., Garner, J.P., Mccain, R.R., Lay Jr, D.C., Eicher, S.D., Marchant Forde, J.N. 2015. An initial investigation into the effects of isolation and enrichment on the welfare of labratory pigs housed in the PigTurn® system, assessed using tear staining, behaviour, physiology and haematology. Animal Welfare. 24:15-27.
Interpretive Summary: Pigs are becoming increasingly important laboratory animals in biomedical sciences and especially in new drug development. Generally, laboratory animals are housed individually, in sterile and barren environments which may result in the animal becoming stressed. This could also therefore result in stress affecting the results of any study and increasing variation in the data, leading to greater animal use and possible inaccuracies in interpretation of the data. Our study investigated whether adding environmental enrichment, a mirror and a rubber mat, and the ability to see another pig would influence the behavior and physiology of pigs undergoing automatic blood sampling in a specially-designed system, the PigTurn, which we have previously shown to be relatively low stress, compared with manual restraint and blood sampling. We found that being isolated and having no enrichment resulted in differential white blood cell counts that indicated higher levels of stress. Conversely, being able to see another pig and having enrichment resulted in lowest cortisol (a stress hormone) levels and differential white blood cell counts that indicated lower levels of stress. However, being able to see another pig but having no enrichment resulted in the highest cortisol levels, indicating that being able to see another animal but not interact may be frustrating, but that this frustration can be removed by appropriate enrichment. We conclude that proximity to another pig coupled with appropriate enrichment would appear to result in the lowest stress levels and therefore improve the pigs' welfare and the potential applicability of results obtained using the system.
Technical Abstract: The pig is an increasingly important laboratory animal species. However, a laboratory often requires individual, sterile housing, which may impose stress. Our objective was to determine the effects of isolation and enrichment in pigs housed for 7 days within the PigTurn™ - a novel penning system with automated blood sampling. Sixteen castrated male (7) and female (9) (Yorkshire × Landrace) weaner pigs were randomly assigned to one of four treatments in a 2 x 2 factorial combination of enrichment (non-enriched or enriched) and isolation (visually isolated or able to see another PigTurn). Pigs underwent catheterization and were placed into the PigTurns 48h post-recovery. They were fed each morning and had ad libitum access to water. Blood was collected automatically daily at 0900 and 1300 h. The morning sample was assayed for cortisol and TNF-alpha, whereas the afternoon sample was used to determine WBC differentials. Behavior was video-recorded and sampled using instantaneous 10-minute scans, to determine behavior and posture time budgets. Data were analyzed as a REML using the MIXED procedure of SAS. Behavior and TNF-alpha was not affected by treatment. Compared to non-enriched pens, enrichment tended to increase proportion of time standing (0.31±0.02 vs. 0.34±0.03, P<0.1) and lying laterally (0.27±0.02 vs. 0.34±0.03, P<0.1) and decrease plasma cortisol (1.8±0.2 µg/dL vs. 1.3±0.1 µg/dL, P<0.05). There was a 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 non-isolated pigs (1.1±0.2 and 2.2±0.2 µg/dL). Eosinophil count differed between treatments, being highest in the enriched/not isolated treatment (0.6±0.1K µL) and lowest in the not enriched/isolated treatment (0.2±0.1K µL, P<0.05), with the other treatments intermediate. The results suggest that being able to see another animal but not interact may be frustrating. The combination of no enrichment and isolation maximally impacts eosinophil numbers. Appropriate enrichment coupled with proximity of another pig would appear to improve welfare.