USING SOUNDS PRODUCED BY PIGS TO IDENTIFY THERMONEUTRALITY ZONES FOR THERMAL ENVIRONMENT ASSESSMENT RATIOS

ABSTRACT Although dry bulb temperature (T) is the environmental variable most commonly used to classify thermal comfort in pigs, environmental assessment ratios provide more accurate information. The objective of this study was to correlate the sound pressure levels (SPL) produced by piglet vocalization with the thermal environment observed during the nursery phase, and subsequently establish thermoneutrality ranges. The experiment was conducted on a pig farm where T, relative humidity (RH), and SPL data were recorded between 9 am-5 pm for 42 days. The association between SPL and T in nursery phase piglets was verified; for thermal comfort to be possible, SPLs were 56.3 to 60.3 dB. The SPLs were subsequently used in predictor equations of ratios, and thermal comfort ranges were 74.4-78.3 for temperature and humidity ratio (THI), and 71.6-75.8 for globe temperature and humidity ratio (BGHI). Although the SPL proved to be a convenient indicator of thermal comfort for the evaluation of pigs, further studies developed in different phases of the production system are required.

摘要 尽管干球温度（dry bulb temperature, T）是当前猪只热舒适等级划分中最常用的环境变量，但环境评估比值可提供更为精准的环境信息。本研究旨在将仔猪保育期的仔猪叫声声压级（sound pressure levels, SPL）与同期观测到的热环境进行关联，并据此建立热中性区间。试验于某生猪养殖场开展，在连续42天内的每日9时至17时记录了干球温度、相对湿度（relative humidity, RH）及声压级数据。研究验证了保育期仔猪的声压级与干球温度之间存在显著关联：当猪只处于热舒适状态时，声压级范围为56.3~60.3 dB。后续以声压级为基础构建了比值预测方程，得出的热舒适区间分别为：温湿指数（temperature and humidity ratio, THI）74.4~78.3，黑球温湿指数（globe temperature and humidity ratio, BGHI）71.6~75.8。尽管声压级被证实为评估猪只热舒适状况的便捷指标，但仍需在养殖系统的不同生长阶段开展进一步相关研究。