Effect of Air Velocity on Laying Hen Performance and Egg Quality

Abstract. Increasing convective cooling can improve the 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 was 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. The 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. Hens were obtained from a commercial farm, 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 air velocity treatments; shell breaking strength was not different between the 0.76 and 1.52 m s^-1 treatments.