| Abstrakt: |
Commercial broiler companies set specific light intensities and photoperiods during different stages of live production to manage bird behavior and growth and to support health and welfare. However, it is currently unknown how much of the floor area in commercial houses is within the target levels set by companies. Therefore, a field survey of twenty 18.3 × 152.4 m broiler houses on five farms was performed to evaluate in-situ light intensity and uniformity in two house sections during brooding [evaporative pad section (pad) and the middle of the house section (mid)] and three sections during tunnel ventilation [pad, mid, and tunnel exhaust fan section (fan)]. Houses ranged in age from new (never used) to aged (5-8 years old). Light intensity measurements were recorded at 70 locations in each of the house sections (140 per house during brooding; 210 per house during tunnel). For tunnel mode, target light intensity values were categorized into above target (>0.22), within target (0.18-0.22 lx), and below target (<0.18 lx). For brooding mode, target light intensity values were below target (<43 lx) and within target (≥43 lx). Geostatistics was used to map and calculate the percentage of floor area above, below, or within target thresholds. During brooding and tunnel conditions, the percent of floor area below target (<43 lx and <0.18 lx, respectively) was higher for aged houses than for new houses in the pad and midsections. All the floor area in the fan section was above target due to light intrusion from operating fans. During tunnel ventilation in the new houses, 4.5%, 6.0%, and 0.0% of the floor area at the pad, center, and fan sections, respectively, were within the 0.18 to 0.22 lx target threshold. However, in the aged houses, only 0.6%, 0.7%, and 0.0% of the floor area at the pad, center, and fan sections, respectively, were within the target range. This research illustrates that the newer houses did a better job at meeting or exceeding target light intensities and that very little of the floor area in new and aged houses during tunnel ventilation was within a 10% threshold of target intensities. Lack of light dimmer adjustment to account for lumen depreciation and accumulation of dust on the bulbs in the aged house most likely led to the lower overall light intensities. Because brood bulbs have a 100% lumen capacity and are not dimmed, a deep cleaning of the bulbs and periodic replacement are recommended if they are not reaching lighting targets. Periodic checking of light intensity is recommended, especially in older houses. [ABSTRACT FROM AUTHOR] |
