A trial was conducted to see if hair hormone concentrations are a good biomarker for chronic stress in pigs. The objective of this study was to determine if different rearing environments, designed to be standard, or improve pig welfare, influenced the hair hormone concentrations of cortisol, cortisone, DHEA, and their ratios. Pigs (n = 192) were raised from birth to slaughter in standard fully slatted barren pens (Control) or slatted pens enriched with daily straw provisions (Straw).
Straw enrichment did not influence hair hormone concentrations or their ratios at 12 and 20 weeks of age. Pigs raised with straw had a lower frequency and duration of negative behaviours (aggression) and a higher frequency of positive behaviours (foraging, play) than control pigs at some, but not all, stages throughout the growing life. Pigs raised with straw had lower skin lesion scores on d27, d56 and d137, improved ADG in the nursery and less tail bites. The behaviour and skin lesion data suggests that pigs raised with straw had improved welfare at some, but not all stages of production, but hair hormones were no different between the populations of pigs. Continued research will look at whether this lack of effect was due to the hair hormone concentrations not being sensitive enough to detect welfare differences, or because provision of straw may not have resulted in great enough changes to reduce chronic stress, or because pigs don’t experience high levels of chronic stress to begin with.
The influence of straw enrichment on hair hormone concentrations, behaviour, and productivity of growing pigs (link to the full article)
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