Ventilation in livestock trailers is a critical welfare variable. Poor ventilation causes heat stress, respiratory disease, and distress in transported animals — particularly during warm weather.
Transport ventilation is a welfare variable that interacts with journey duration, ambient temperature, stocking density, and animal physiology. Pigs are particularly vulnerable: they cannot sweat and rely on respiration for heat dissipation, making them susceptible to hyperthermia at temperatures and densities that cattle or sheep might tolerate. Static ventilation through slat openings depends on vehicle movement to generate airflow — vehicles that stop in traffic or in loading bays lose ventilation entirely. Forced air systems maintain airflow independently of vehicle movement but are more expensive to install and maintain. Driver awareness of thermal risk, route planning to avoid peak heat periods, and regular checks at rest stops are all important complementary interventions. Temperature and humidity logging in transport vehicles enables post-journey welfare auditing and supports accountability.