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ARS Home » Southeast Area » Mississippi State, Mississippi » Poultry Research » Research » Publications at this Location » Publication #297792
Title: Effects of air velocity on laying hen production from 24 to 27 weeks under simulated evaporatively cooled conditions

Author
item Purswell, Joseph - Jody
item Branton, Scott
item LUCK, B - Mississippi State University
item DAVIS, J - Mississippi State University

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/9/2013
Publication Date: 12/12/2013
Citation: Purswell, J.L., Branton, S.L., Luck, B.D., Davis, J.D. 2013. Effects of air velocity on laying hen production from 24 to 27 weeks under simulated evaporatively cooled conditions. Transactions of the ASABE. 56(6):1503-1508.

Interpretive Summary: Thermal conditions play a major role in production efficiency in commercial poultry production and reduction of thermal stress can improve productivity, but must be achieved economically. Increased air movement has been shown to improve production efficiency when weather and system design limit effectiveness of evaporative cooling in other poultry species. 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, feed consumption (FC), feed consumption/dozen, feed conversion ratio, and egg weight. 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. Hens (Hy-line W-36 breed) were obtained from a commercial laying operation and placed in purpose-built wind tunnels. 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. Results showed that hen-day egg production for the 1.52 m/s treatment group improved by 4.0% and 3.4% over still air and 0.76 m/s, respectively. Feed consumption was observed to increase with air velocity. Other measures of performance including egg weight and feed conversion ratio were not different, suggesting that the improvement in hen-day egg production resulted from increased feed conversion. Additional cooling through increased air movement shows promise for increasing productivity of laying hens during hot weather by improving thermal comfort when evaporative cooling is limited by weather or system design.

Technical Abstract: 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. Air velocity test units (wind tunnels) containing cages were constructed; still air treatment groups were housed in identical cage units without the surrounding wind tunnel structure. Four trials were conducted, with two replicate treatment groups per trial, for a total of eight replicate treatment groups in the study. Hens (Hy-line 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 test cages; 48 hens were used in each trial, with eight hens per replicate 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. Results showed that HDEP for the 1.52 m/s treatment group improved by 4.0% and 3.4% over still air and 0.76 m/s, respectively. FC was observed to increase with air velocity (P<0.05). Other measures of performance including EW and FCR were not different, suggesting that the improvement in HDEP resulted from increased FC. Increased convective cooling shows promise for increasing productivity of laying hens during hot weather by improving thermal comfort when evaporative cooling is limited by weather or system design.