Effects of Air Velocity on Laying Hen Production

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<abstract> <bold>Abstract.</bold> Thermal conditions play a major role in production efficiency in commercial poultry production. Mitigation of thermal stress can improve productivity, but must be achieved economically. Weather and system design can limit effectiveness of evaporative cooling and increased air movement has been shown to improve production efficiency in broilers. The objective of this study was to evaluate the effects of increased air velocity on productivity of laying hens by assessing hen-day egg production (HDEP), feed consumption (FC), feed consumption/dozen (FD), feed conversion ratio (FCR), and egg weight (EW). Three treatments were tested (still air, 0.76 m/s, and 1.52 m/s) at 27.8° C and 82% RH to mimic an evaporatively cooled poultry house in the southeastern US under summer weather conditions. Four air velocity test units (wind tunnels) were constructed, each containing cage units which held 10 individual bird cages; still air treatment groups were housed in identical cage units without the surrounding wind tunnel structure. Hens (W-36 breed) were obtained from a commercial laying operation at 23 weeks of age and housed in an adjacent facility until transfer into the wind tunnel units; 48 hens were used in each trial, with eight hens per treatment group. Feed and water were provided ad libitum and the lighting program followed primary breeder recommendations. Eggs were collected and group weighed for each treatment group for 28 days (four one-week periods) and feed consumption was assessed weekly. Three trials were conducted, with two replicate treatment groups per trial, for a total of six replicate treatment groups in the study. Results showed that HDEP for the 1.52 m/s treatment group improved by 5.2% and 3.8% over still air and 0.76 m/s, respectively. Increased FC was observed with increased air velocity, and was significantly different for all treatments. Other measures of performance including EW, FD, and FCR were not different, suggesting that the improvement in HDEP resulted from increased FC. Increased convective cooling may hold promise for increasing egg production rates during hot weather by improving thermal comfort when evaporative cooling is limited by weather or system design.