Low Airspeed Impacts on Tom Turkey Response to Moderate Heat Stress

Heat stress is a concern for turkeys in naturally ventilated houses. Chamber and room studies were used to assess heat stress at moderate temperatures (<25 °C) and low airspeeds on grown tom turkeys. In the chamber study, four ventilation rates × two temperatures (thermal comfort and thermal stress, 11 °C above thermal comfort) were applied to 13- to 19-week birds. Very small differences in airspeeds among the four treatments masked subcutaneous, cloacal, and infrared (IR) temperature differences at both temperatures. In the room study, four ventilation rates (0.07 m3·min−1·kg−1 or 100%, 75%, 50%, and 30% or Control) were applied to 21-week toms housed at <23 °C. The Control treatment had significantly higher whole-body and head temperatures vs. the other treatments. Only 100% had higher weight gain vs. 50%; hematology was unaffected by treatment. Higher ventilation rates reduced heat stress due to lower room temperatures, not airspeed differences, which were very low. The low-cost IR camera detected a heat stress difference ≥ 0.8 °C, corresponding to wind chill of 0.8 °C due to an airspeed of 0.8 m·s−1 vs. still air on the USDA broiler wind chill curve. Machine vision combined with IR thermography could alleviate real-time poultry heat stress.