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Title:Assessing the well-being of gestating submissive sows in group pens using multiple welfare metrics
Author(s):Pacheco, Eridia
Advisor(s):Salak-Johnson, Janeen
Contributor(s):Stein, Hans; Ellis, Micheal
Department / Program:Animal Sciences
Discipline:Animal Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):sow housing
social rank
Abstract:Housing in the swine industry is one of the most controversial issues in animal agriculture today, specifically how to keep gestating sows. Internationally, many countries such as the European Union, Canada, and Australia, as well as some states within the U.S. have banned gestation crates. Consumer and legislative pressure have been the greatest push for these changes, despite studies concluding that group housing and individual gestation crates are both acceptable housing systems with regards to animal welfare. Group housing of sows does allow for social interactions and increased levels of mobility, however the greatest consequence is increased aggression among group-housed sows. The highest level of aggression within a group-pen system occurs during mixing in order to establish social hierarchy and around resources (e.g., water, feeding). Although, aggression is inevitable among group-housed sows in stabilizing social hierarchy, aggression can affect sow productivity and well-being, especially among submissive sows. Therefore, minimizing aggressive encounters using management and dietary strategies may be factors used in a group housing system to improve sow well-being among the submissive sows. The objective of this thesis was to (1) assess the well-being of submissive sows housed in small group pens fed modified gestation diets supplemented with dietary fiber (MIDDS-HULLS or DDGS-GM) with a competitive feeding system which includes feeding stalls of two different lengths (LONG or SHORT), and (2) to determine the effect of social status on the stress responsiveness of these sows using multiple welfare metrics. Prior to moving into experimental pens, a feed competition test was used to determine social rank by calculating a dominance value (DV) for each sow within a treatment pen, based on aggressive encounters that occurred during the test period. The two sows with the highest DV were identified as dominant (DOM) and two sows with the lowest DV were identified as submissive (SUB). This sub sample from a larger study was analyzed separately and used for this thesis (n=64). Sow performance, productivity, behavior, immune and endocrine statuses were assessed throughout gestation to determine sow well-being. Data were analyzed using PROC MIXED with repeated measures and PROC GLIMMIX for ordinal data (SAS). Interactive effects of feeding stall and dietary fiber with social rank were found to affect sow performance, behavior, productivity, and immune status. Socially, SUB sows had greater performance when housed in pens with LONG feeding stalls (social status × stall length; P < 0.02) and fed MIDDS-HULLS diet (social status × diet; P < 0.01). Aggressive encounters decreased (P < 0.02) and socially, SUB sows had greater productivity (P < 0.01) when housed in pens with LONG feeding stalls and fed DDGS-GM diet (social status × diet × stall length). Results reported within imply that socially dominant and submissive gestating sows perceive and cope with social stress by evoking different biological responses, and that a combination of management and dietary strategies can improve well-being of submissive sows; therefore, social status should be considered when keeping gestating sows in small group pens using a competitive feeding system.
Issue Date:2016-04-29
Rights Information:Copyright 2016 Eridia Pacheco
Date Available in IDEALS:2016-07-07
Date Deposited:2016-05

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