Thermal stress can result in productivity losses, morbidity, and mortality if proper management practices are not employed. A basic understanding of the relationship between animals and the thermal environment is crucial to assess the environment’s impact on livestock performance. Therefore, the study objective was to evaluate whether different early life thermal stressors (ELTS) altered the temperature preference of pigs later in life. Twelve sows and their litters were randomly exposed to 1 of 3 ELTS treatments from 7 to 9 d of age: early life heat stress (ELHS; cycling 32 to 38 °C; n = 4), early life cold stress (ELCS; 25.4±1.1 °C without heating lamp; n = 4), or early life thermoneutral (ELTN; 25.4±1.1 °C with a heating lamp; n = 4) conditions. From 10 to 20 d, (weaning) all piglets were exposed to ELTN conditions. At weaning, pigs were randomly assigned to groups of 4 of the same sex and ELTS treatment. Temperature preference, where pigs freely choose a temperature, was assessed in 21 groups (n = 7 groups per ELTS treatment) using 1 of 3 thermal gradient apparatuses (22 to 40 °C). Testing began at 26 ± 1.3 d of age to give pigs time to acclimate to solid food after weaning and 1 group per ELTS treatment were tested simultaneously in each apparatus. Pigs were given 24 h to acclimate followed by a 24-h testing period. Behavior (active and inactive), posture (upright, sternal, and lateral lying), and location were documented every 20 min using instantaneous scan samples. Preferred feeding temperature was determined by the latency to empty a feeder in each location. Data were analyzed using PROC MIXED in SAS 9.4. A cubic regression model was used to calculate the peak temperature preference of pigs based on the temperature pigs spent most of their time. The preference range was calculated using peak temperature preference ±SE for each ELTS treatment group. Early life thermal stress altered where pigs spent most of their time within the thermal gradient (P = 0.03) with ELTN pigs preferring cooler temperatures (peak preference of 23.8 °C) compared with their ELCS exposed counterparts (peak preference of 26.0 °C; P < 0.01). However, ELHS exposed pigs (peak preference of 25.6 °C) did not differ in their temperature preference compared with ELTN or ELCS exposed counterparts (P > 0.05). In summary, ELCS exposure altered pig temperature preference later in life indicating that ELTS can alter temperature preference in pigs.

中文翻译：

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早期生命热应激：对断奶仔猪（3至15公斤）未来温度偏好的影响

如果不采取适当的管理措施，热应力会导致生产率下降，发病率和死亡率下降。对动物与热环境之间关系的基本了解对于评估环境对牲畜性能的影响至关重要。因此，本研究的目的是评估不同的早期生命应激源（ELTS）是否会改变猪后期的温度偏好。在7至9 d的年龄中，将12头母猪及其垫料随机接受3种ELTS处理中的1种：早期热应激（ELHS；循环32至38°C；n = 4），早期冷应激（ELCS ; 25.4± 1.1°C（不带加热灯；n = 4）或早期热中性（ELTN ; 带加热灯的25.4±1.1°C; n = 4）条件。在10至20天（断奶），所有仔猪均暴露于ELTN条件下。断奶时，将猪随机分为4组，每组相同性别，并进行ELTS治疗。温度优选地，其中猪自由选择的温度下，在21组中评估（Ñ=使用3个热梯度仪（22至40°C）中的1个，每个ELTS处理7组。测试从26±1.3 d年龄开始，为断奶后的猪提供时间使其适应固体食物，并且每台ELTS处理中的1组在每种设备中同时进行测试。给猪24小时适应环境，然后进行24小时测试。使用瞬时扫描样本每20分钟记录一次行为（活动和不活动），姿势（直立，胸骨和侧卧）和位置。优选的进料温度由每个位置清空进料器的等待时间确定。使用SAS 9.4中的PROC MIXED分析数据。三次回归模型用于根据猪大部分时间的温度来计算猪的峰值温度偏好。使用每个ELTS治疗组的峰值温度偏爱±SE计算偏爱范围。早期生命的热应力发生了变化，其中猪大部分时间都在热梯度中度过（P = 0.03），相比于ELCS暴露的同类动物（峰值优选26.0°C；P <0.01），ELTN猪更喜欢较低的温度（峰值优选23.8°C ）。然而，与ELTN或ELCS暴露的同类猪相比，暴露于ELHS的猪（峰值优选25.6°C）的温度偏好没有差异（P > 0.05）。总而言之，ELCS暴露在生命后期改变了猪的温度偏好，表明ELTS可以改变猪的温度偏好。