USE OF PROTECTION SCREEN IN CONVENTIONAL AVIARIES (CALIFORNIAN TYPE) FOR LAYING HENS

ABSTRACT The objective of this work was to evaluate the thermal environment inside conventional cages for laying hens, with and without the use of protective screens. This research was conducted in two conventional cages (open cage), where each cage had half of its area surrounded by high density polyethylene mesh (HDPE) with a diameter of 2.0 cm, and the other half was kept fully open. Hyline W-36 and Dekalb Brown laying hens were housed in these cages. The wind speed, dry bulb temperature (tdb), black globe temperature, humidity index (BGHI), and enthalpy (H) were analyzed. The results indicate that the use of the screen reduced the wind speed inside the cage by 0.22 m s−1. The presence of the screen affected tdb, BGHI, and H in some of the evaluated periods evaluated, making these values higher than those of the treatment without screen. However, the obtained values are within or below the thermal comfort range for laying birds. Therefore, the use of HDPE screen in the cages altered their internal environment. However, it is not enough to hinder the thermal comfort of the housed animals.摘要 本研究旨在评估加装与未加装防护网的蛋鸡常规笼舍内部热环境。本实验于两个常规开放式蛋鸡笼舍中开展，每个笼舍的一半区域采用直径2.0厘米的高密度聚乙烯（high density polyethylene, HDPE）网围合，另一半保持完全开放。海兰W-36与迪卡棕蛋鸡被饲养于上述笼舍中。本研究对风速、干球温度（dry bulb temperature, tdb）、黑球温度、湿黑球温度指数（black globe temperature humidity index, BGHI）以及焓（enthalpy, H）进行了分析。结果显示，加装防护网可使笼舍内风速降低0.22 m·s⁻¹。在部分评估周期内，防护网的存在会对干球温度、湿黑球温度指数与焓产生影响，使这些指标数值高于未加装防护网的实验组。但测得的所有数值均处于或低于蛋鸡的热舒适区间。因此，在笼舍中使用HDPE网会改变其内部环境，但并未对饲养动物的热舒适状态造成不利影响。