The Contribution of Air Velocity to the Effective Temperature for Laying Hens

Abstract

Three series of experiments were carried out to estimate the contribution of air velocity to the effective temperature for laying hens under controlled environments (dry-bulb temperature, DBT=25-35°C, air velocity, AV=0.05-4m/s), using respiration rate as an informative index. The effective ratios of ET (DBT, WBT) (effective temperature of DBT and WBT for laying hens=0.75•DBT+0.25•WBT):√AV on respiration rate were as follows, for free living hens in the cage; 1:4.9, for restrained hens; 1:2.6-2.7. Also the ratios of DBT: √AV were 1:5.2 and 1:2.7-2.9 respectively. Therefore, the corrected effective temperature with air velocity can be expressed as follows, ET (DBT, WBT, AV)=0.75•DBT+0.25•WBT-(2.6-4.9)•√AV, or ET (DBT, AV)=DBT-(2.7-5.2)•√AV. The differences in the coefficient of √AV were thought to be a consequence of varying orientation and posture of the hens influencing the AV experienced. The results suggest that the effectiveness of AV could be widely modified by feather conditions of hen as well as their behavior.