Radiant Flux Preference of Neonatal Broiler Chicks During Brooding

Abstract

Abstract. Radiant heat is the most common method of providing supplemental heat in a broiler house. However, little information exists about chick preference for radiant flux. Identifying the ranges of radiant flux that chicks prefer would allow improved management of the thermal environment. The objectives of this study were to determine the radiant flux ranges preferred by broiler chicks during the first eight days of brooding. Three trials were conducted using straight-run broiler chicks. A total of 88 chicks were randomly allocated into two mixed-gender groups and placed into identical 1 m × 4 m pens for 8 d. Heat lamps were used to create radiant flux zones of 30, 70, 175, and 450 W m-2 in each pen. Chicks were allowed to move freely between the zones, and feed and water were available in each treatment area. Chick location was recorded with a camera at 5 min intervals. For each image, non-linear regression analysis was applied to the cumulative proportion of chicks in each treatment. The resulting equations were used to calculate the range of radiant flux values for which 80% of the chicks exhibited a preference. Chicks exhibited a preference for decreasing radiant flux with age. The mean maximum preferred radiant flux for all trials decreased from 409.4 W m-2 at 1 d to 304.4 W m-2 at 8 d. The mean minimum preferred radiant flux for all trials decreased from 114.5 W m-2 at 1 d to 31.4 W m-2 at 8 d. Keywords: Broiler chicks, Brooding, Radiant flux, Radiant heaters, Thermal preference.