|Purswell, Joseph - Jody|
Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/25/2015
Publication Date: 7/1/2015
Citation: Purswell, J.L., Branton, S.L. 2015. Effect of air velocity on laying hen performance and egg quality. Transactions of the ASABE. 58(3):813-817.
Interpretive Summary: Reducing heat stress to improve thermal comfort enhances production in efficiency in poultry, and can mitigate economic losses from depressed feed intake which results in reduced production. Increased air movement has been shown to improve feed intake and egg production in laying hens. The objective of this study was to evaluate the effects of increased air velocity on egg production and quality in mid-cycle laying hens. 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 U.S. Hens were obtained from a commercial laying operation and housed in wind tunnels for 10 weeks to assess production and egg quality attributes. Results showed that egg production rates for the two air velocity treatments improved by 6.7% and 6.3% for 1.52 and 0.76 m/s, respectively; increases in feed intake mirrored the increases in egg production rate. Egg weight was significantly heaver as air velocity increased, with a maximum difference of 4.3 g/egg between the 1.76 m/s and still air treatments. Egg weight variability also decreased with increasing air velocity. Albumen quality (as assessed by Haugh unit scoring) was reduced for increased air velocities, but remained above grading quality requirements for AA quality. Egg shell breaking strength was significantly reduced for the still air treatments. Additional research is needed to better understand the links between convective cooling and differences in egg weights and egg weight distribution.
Technical Abstract: Increasing convective cooling can improve performance and thermal comfort of commercial poultry when weather or system design limit cooling through other means such as evaporative cooling. Previous work in young hens showed increased egg production rate as feed intake is maintained under heat stress conditions. However, the effects of increased convective cooling on live performance or egg quality in older hens have not been evaluated. The objective of this study was to evaluate the effects of different air velocities on live performance of laying hens from 39 to 48 weeks of age and resultant egg quality. Air velocity treatments included still air, constant 0.76 m s-1, and constant 1.52 m s-1; temperature and relative humidity in the experimental room were maintained at 27.8 °C and 82%, respectively. Two 10-week trials were conducted, with two replicate treatment units per trial, for a total of four replicate treatment units in total. Hens were obtained from a commercial farm and placed in wind tunnels and provided feed and water ad libitum; lighting was provided per primary breeder guidelines. Eggs were collected daily and feed intake was assessed weekly; egg quality attributes including egg weight, albumen quality (Haugh unit score), incidence of meat and blood spots, and egg shell strength were measured twice weekly. Hen-day egg production increased 6.3 and 6.7% over still air for 0.76 and 1.52 m s-1, respectively (p < 0.0001). Feed intake was significantly depressed for still air when compared to air velocity treatments (p < 0.0001). Mean egg weight increased with increasing air velocity and was significantly different for all treatments (p < 0.0001). Albumen height and quality (Haugh unit) decreased with increasing air velocity and were significantly different between the still air and 1.52 m•s-1 treatments (p < 0.0038). Shell breaking strength significantly decreased for the still air treatment (p < 0.0001) when compared to the remaining air velocity treatments; shell breaking strength was not different between the 0.76 m•s-1 and 1.52 m•s-1 treatments.