OPTIMIZATION OF PARTIAL SURFACE WETTING TO COOL CAGED LAYING HENS

Abstract

Partial surface wetting to cool caged laying hens (HyLine W98 breed, 34 1 wk) was investigated for a rangeof acute heat challenge conditions. The cooling water required to prevent surface and core body temperatures of the hen fromescalating was expressed in terms of water spray interval (SI10, min) at a constant spray dosage (10 mL hen1) and evaporationrate (ER, mL min1) of the sprayed water. The thermal conditions used in this study consisted of air velocity (V) of 0.2 to 1.2 ms1 in combination with air vapor pressure deficit (VPDair) of 2.1 to 5.3 kPa that corresponds to drybulb temperature (tdb)of 35C to 41C and dewpoint temperature (tdp) of 21C to 27C. ER was directly proportional to VPDair V. The empiricalrelationships provide a basis for optimizing operation of partial surface wetting systems to relieve caged layers of heat stressin commercial production settings.