This little piggy got cold: Door flaps on outdoor farrowing huts improve piglet survival during winter in Australia

Pigs in outdoor production systems have opportunities to engage in experiences that enhance their welfare but are also challenged with stressors like coping with harsh climatic conditions. Cold weather is a particular challenge for neonatal piglets that have a limited capacity to thermoregulate and increased risk of dying in winter. This research examined if adding door coverings to outdoor farrowing huts in winter could increase the temperature of pigs’ shelters and translate to improved thermal comfort and survival for piglets. Two hundred litters were studied over six time replicates from early winter until early spring at a commercial piggery in Australia. Pigs were housed in group farrowing paddocks containing eight huts each. A randomised complete block design was used to assign treatment (with or without a rubber door flap over the entryway) to huts within each paddock. Hut microclimate, piglet thermoregulatory behaviours, and piglet survival were examined. Door flaps were effective at increasing temperature, with the daily minimum temperature in huts with door flaps 2.4°C (SE = 0.2) warmer than huts without (p < 0.0001). Door flaps had no negative effects on other aspects of the hut microclimate, including humidity, ammonia, or bedding moisture (p > 0.05). Piglets in huts with door flaps compared to without were less likely to shiver from 0 to 4 days of age (OR = 0.77; 95 % CI = 0.39–1.50; p = 0.0002). At this same age, there was also an indication that piglets from huts with door flaps were less likely to be in physical contact with the sow when resting, although the evidence was not strong (OR = 0.81; 95 % CI = 0.66–1.0; p = 0.057). There was no significant effect of door flaps on huddling behaviour (p > 0.05). While door flaps had no significant effect on the number of piglet losses within 24 h of age before piglet processing, they improved survival after this time. Specifically, door flaps reduced the hazard of piglets dying between processing until 12 days of age by a factor of 0.65 (95 % CI = 0.47–0.89; p = 0.007). These findings demonstrate that simple modifications to existing outdoor farrowing huts can improve thermal comfort and piglet survival in winter. Overall, door flaps present a practical and beneficial strategy for improving piglet welfare and farm productivity in outdoor systems, even in relatively moderate climates like Australia.