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Journal of Animal Science Abstract - Animal Production

Effects of varying floor space on aggressive behavior and cortisol concentrations in group-housed sows1

 

This article in JAS

  1. Vol. 94 No. 11, p. 4809-4818
     
    Received: Apr 27, 2016
    Accepted: Aug 26, 2016
    Published: October 13, 2016


    2 Corresponding author(s): phh@unimelb.edu.au
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doi:10.2527/jas.2016-0583
  1. P. H. Hemsworth 2*,
  2. R.S. Morrison,
  3. A. J. Tilbrook,
  4. K. L. Butler,
  5. M. Rice* and
  6. S. J. Moeller#
  1. * Animal Welfare Science Centre, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, VIC 3010, Australia
     Rivalea Australia, Corowa, NSW 2646, Australia
     Animal Welfare Science Centre, South Australia Research and Development Institute, University of Adelaide, Roseworthy, SA 5371, Australia
    § Biometrics Group, Department of Economic Development, Jobs, Transport & Resources, Hamilton, VIC 3030, Australia
    # Animal Welfare Science Centre, Department of Animal Science, The Ohio State University, Columbus, 43210

Abstract

Floor space is an important determinant of aggression and stress in group-housed sows, and the aim of the present experiment was to comprehensively examine the effects of floor space in the range of 1.45 to 2.90 m2/sow from mixing until 27 d after insemination on aggression, stress, and reproduction of group-housed sows. A previous experiment on the effects of floor space indicated spatial variability across and along the research facility in both sow aggression and stress. To minimize this spatial variability within the research facility, similar-sized pens but with varying groups sizes (10–20) in 4 separate blocks of 3 contiguous pens within each of 9 time replicates (180 sows/replicate) were used to examine 6 space allowances (1.45–2.9 m2/sow). Space treatments were appropriately randomized to pens. Although it may be argued that space allowance is confounded with group size in this design, there was no evidence in our previous experiment of group size effects, for pens of 10 to 80 sows, or appreciable interactions between space and group size on aggression, stress, and reproduction. In the present experiment, sows were introduced to treatments within 4 d of insemination and were floor fed 4 times per day (2.5 kg/sow per d). On both Days 2 and 26 after mixing, aggressive behavior (bites and knocks) at feeding and plasma cortisol concentrations were measured. Restricted maximum likelihood mixed model analyses were used to examine the treatment effect after accounting for replicate and random spatial location effects within replicate. There was a consistent linear effect of floor space allowance on aggression at feeding at Day 2 (P < 0.0001) and plasma cortisol concentrations at Day 2 (P = 0.0003), with aggression and stress declining with increasing space. However, there were no effects of space allowance on aggression and stress at Day 26 (P = 0.14 and P = 0.79, respectively). These results show that increased floor space in the immediate post-mixing period reduces aggression and stress and that sows may adapt to reduced floor space over time. A strategy of staged-gestation penning, with more space immediately after mixing and less space later in gestation, may address both animal welfare and economic considerations, but this clearly requires further examination.

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