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What is causing smothering in laying hens?
  1. Sabine G. Gebhardt-Henrich, MSc, PhD1,3 and
  2. Ariane Stratmann, MSc, PhD2,3
  1. 1e-mail:
  2. 2e-mail:
  3. 3Center for Proper Housing: Poultry and Rabbits (ZTHZ), Division of Animal Welfare, VPH Institute, University of Bern, 3052 Zollikofen, Switzerland

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LAYING hens crowding in corners or other places in the barn or veranda, ‘piling up’, can lead to the birds smothering each other. This is a well-known but unpredictable event causing losses to producers and negatively affecting animal welfare. The cause and the process of this phenomenon are hard to explain as detection is normally after the incident when a few to several hundred dead laying hens are found. As highlighted in a paper summarised on p 252 of this issue of Veterinary Record by Rayner and others (2016), there are three smothering categories in relation to location and presumed causes: panic smothers, nest box smothers and recurring smothers. The paper is the second part of a questionnaire-based study of smothering in the UK where a preliminary study and the first part of the questionnaire study demonstrated that smothering events were responsible for a sizable portion of overall flock mortality with more than 50 per cent of surveyed flocks being affected (Bright and Johnson 2011), and that the location and timing of the event was variable among farms (Barrett and others 2014). Data for this epidemiological study were obtained from more than 200 farms in the McDonald's Sustainable Egg Supply Group, representing 35 per cent of the UK free-range egg supply.

Given that producers detected …

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