Renaudeau David
PEGASE UMR1348, Physiologie, Environnement et Génétique pour l'Animal et les Systèmes d'Élevage, INRAE, Institut Agro, St Gilles, France.
Transl Anim Sci. 2020 Oct 13;4(4):txaa192. doi: 10.1093/tas/txaa192. eCollection 2020 Oct.
The objectives of this study were to determine the effects of single or repeated short heat stress (HS) challenges that mimicked summer heat waves on performance and thermoregulatory responses in finishing pigs. A total of 45 crossbred castrated males were tested in three consecutive replicates of 15 pigs. Within each replicate, pigs were assigned to one of five treatments. Pigs in treatment group TTT were maintained in thermoneutral conditions (22 °C) for the entire experiment (45 d). Pigs in treatment group HHH were subjected to an HS challenge (32 °C for 5 d) at 113, 127, and 141 d of age (in experimental periods P1, P2, and P3, respectively). Pigs in treatment groups HTT, THT, and TTH were subjected to the HS challenge at 113, 127, or 141 d of age, respectively. Each 5-d challenge was preceded by a 3-d prechallenge period and followed by a 7-d recovery period. Pigs were housed in individual pens and fed ad libitum. HS significantly reduced average daily feed intake (ADFI) and the average daily gain (ADG). Expressed as a percentage of the performance observed during the prechallenge period, ADFI decreased by 12%, 22%, and 26% and ADG decreased by 12%, 43%, and 72% in the HTT, THT, and TTH groups, respectively. Regardless of the experimental group, no compensatory performance was observed during the recovery period, suggesting that HS has a long-lasting effect on animal performance. Pigs subjected to HS had an immediate increase in core body temperature (T), skin temperature, and respiratory rate, all of which gradually decreased during the HS challenge. Based on T measurements, hypothermia was observed during the recovery period in each of the three experimental periods, especially for pigs in the HHH and the HTT groups but only during the first HS cycle. Repeated exposure to HS for the HHH group resulted in heat acclimation responses characterized by a lower increase in T and lower decrease in ADFI during P2 and P3 than during P1.
本研究的目的是确定模拟夏季热浪的单次或重复短期热应激（HS）挑战对育肥猪生产性能和体温调节反应的影响。总共45头杂交去势公猪分三个连续批次进行测试，每个批次15头。在每个批次内，猪被分配到五种处理方式之一。处理组TTT中的猪在整个实验期间（45天）维持在热中性条件（22℃）下。处理组HHH中的猪在113、127和141日龄时（分别在实验阶段P1、P2和P3）接受热应激挑战（32℃，持续5天）。处理组HTT、THT和TTH中的猪分别在113、127或141日龄时接受热应激挑战。每次5天的挑战之前有3天的预挑战期，之后有7天的恢复期。猪单独饲养，自由采食。热应激显著降低了平均日采食量（ADFI）和平均日增重（ADG）。以预挑战期观察到的生产性能的百分比表示，HTT、THT和TTH组的ADFI分别下降了12%、22%和26%，ADG分别下降了12%、43%和72%。无论实验组如何，在恢复期均未观察到补偿性生产性能，这表明热应激对动物生产性能有长期影响。接受热应激的猪核心体温（T）、皮肤温度和呼吸频率立即升高，在热应激挑战期间均逐渐下降。根据体温测量，在三个实验阶段的每个恢复期均观察到体温过低，尤其是HHH组和HTT组的猪，但仅在第一个热应激周期出现。HHH组重复暴露于热应激导致热适应反应，其特征是与P1相比，P2和P3期间体温升高幅度较小，ADFI下降幅度较小。
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