Impact of Social Buffering and Restraint on Welfare Indicators during UK Commercial Horse Slaughter

Current legislation in the United Kingdom stipulates that horses should not be slaughtered within sight of one another. However, abattoir personnel anecdotally report that, for semi-feral unused to restraint, co-slaughtering alongside a conspecific could reduce distress through social buffering and improve safety, but there is lack evidence support this. CCTV footage from an English was assessed retrospectively with welfare indicators when entered kill pen until they were killed. Of 256 analysed, 12% (32/256) co-slaughtered (alongside conspecific) 88% (224/256) individually. Co-slaughtered moved more pen, individually showed agitated behaviour, required encouragement enter experienced slips or falls. Unrestrained (40%; 102/256) increased agitation, movement, agonistic behaviour towards operator resisted entry compared restrained (60%; 154/256). Positive interactions between conspecifics seen 94% (30/32) horses, only 6% (1/16) startled response first horse being shot, median time 15 s shots. This study highlights impact both human can have on equine at slaughter. Semi-feral unrestrained appear experience familiar handling, presence slaughter mitigated