Thermal comfort and grazing behavior of Girolando heifers in integrated crop-livestock (ICL) and crop-livestock-forest (ICLF) systems

ABSTRACT. To compare the integrated crop-livestock-forest (ICLF) and crop-livestock (ICL) systems in relation to thermal comfort and grazing behavior of Girolando heifers, a 2 × 2 crossover trial (two system and two periods) was carried out with eight – Holstein × ¼ Gyr heifers in Xaraés-palisade grass pasture under intermittent stocking with 10 days of occupation period and 20 days of resting. In ICLF, crown cover of eucalyptus planted in rows was 65% at the beginning of the experiment. Animal behavior was assessed through bioacoustics by recording heifers’ sounds for 48 hours. Concomitantly, heifers’ internal temperature (IT, °C) was recorded every 10 min using data logger thermometers adapted to hormone-free intravaginal devices. Air temperature and humidity data were collected by thermohygrometers located in the center of ICLF and ICL for calculating Temperature-Humidity Index (THI). According to THI values, ICLF and ICL did not vary in terms of thermal comfort. However, THI indicated moderate stress (82.26±4.40) during day (06:00 to 17:59h) and mild stress (75.76±4.38) at night (18:00 to 05:59h) in both systems. During day, heifers from ICL had significantly (p摘要：为比较农牧林复合系统（integrated crop-livestock-forest, ICLF）与农牧复合系统（crop-livestock, ICL）对吉罗兰特小母牛热舒适状况与采食行为的影响，本研究采用2×2交叉试验设计（设置2种系统、2个试验周期），在采用间歇放牧制度（放牧期10天、休牧期20天）的Xaraés-篱垣草牧场开展试验，试验动物为8头荷斯坦×1/4吉尔小母牛。在农牧林复合系统中，试验初期成行种植的桉树冠层覆盖率为65%。本研究通过生物声学技术记录小母牛48小时的叫声以评估其行为表现；与此同时，使用适配无激素阴道内置装置的数据记录温度计，每10分钟记录一次小母牛的体内温度（internal temperature, IT，℃）。在农牧林复合系统与农牧复合系统的中心区域放置温湿度计，采集空气温湿度数据以计算温湿度指数（Temperature-Humidity Index, THI）。基于温湿度指数结果，农牧林复合系统与农牧复合系统的热舒适状况无显著差异。但两个系统的温湿度指数均显示，日间（06:00至17:59）存在中度应激（82.26±4.40），夜间（18:00至05:59）存在轻度应激（75.76±4.38）。日间，农牧复合系统中小母牛的相关指标显著（p