ASABE Technical Library - Abstract

Abstract.

Radiant heat is the most common method of providing supplemental heat in a broiler house. Little information exists about chick preference for radiant flux. Identifying the ranges of radiant flux that chicks prefer would allow for improved management of the thermal environment. The objectives of this study were to determine radiant flux ranges preferred by broiler chicks during the first eight days of brooding. Two trials were conducted using straight-run broiler chicks. A total of 88 chicks were randomly allocated into two groups and placed into two identical 1 m x 4 m pens for 7 d. Heat lamps were used to create radiant flux treatments of 30, 70, 175, and 450 W·m^-2 in each pen. Chicks were allowed to move freely between the treatments and feed and water were available in each treatment area. Chick location was recorded with a web-camera at 5 min intervals. For each image, non-linear regression analysis was applied to the cumulative proportion of chicks in each treatment as a function of radiant flux. 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 decreasing preference for radiant flux with age. Least squares mean maximum preferred radiant flux decreased from 386.9 W·m^-2 at 0 d to 248.31 W·m^-2 at 7 d, while the minimum preferred radiant flux decreased from 61.2 W·m^-2 at 0 d to 7.7 W·m^-2 at 7 d.