University of New England, Armidale, New South Wales, 2351, Australia; CRC for Sheep Industry Innovation, Armidale, NSW, 2350, Australia.
University of New England, Armidale, New South Wales, 2351, Australia; CRC for Sheep Industry Innovation, Armidale, NSW, 2350, Australia.
J Therm Biol. 2020 May;90:102606. doi: 10.1016/j.jtherbio.2020.102606. Epub 2020 Apr 28.
Understanding circadian rhythms of body temperature is important for the interpretation of single body temperature measurements and the assessment of the physiological state of an animal. The ability to measure body temperature at peripheral locations may also be important in the development of minimally invasive tools for remote temperature measurement in livestock. This study aimed to investigate how well body temperature measured at peripheral sites reflected a commonly used core measurement (vaginal temperature) and the circadian rhythmicity of the body temperature of sheep with a view to practical application in extensive sheep production systems. Eleven crossbred ewes were implanted with peripheral temperature sensing microchips (LifeChip®) which were positioned transversely in the sternocleidomastoid (neck) muscle and subcutaneously under the tail. iButton® temperature loggers were placed intravaginally to record core body temperature measurements (Tv). The body temperature measurements observed at the peripheral sites in the neck (Tn) and tail (Tt) differed significantly to those measured at the core site, Tv (P < 0.05), with Tn lower than Tv and Tt lower than both Tv and Tn. Similarities in circadian rhythm patterns were observed across the day between Tv, Tn and Tt in repeated measures analysis, with a short period of difference between Tv and Tn (from 1400 to 1600 h) and a long period of difference between Tv and Tt (from 1000 to 2100 h) (P < 0.05). These results suggest that neck muscle temperature measurements may have utility in detecting circadian rhythm patterns in core temperature in sheep, but may not accurately reflect absolute core temperatures. Peripheral measures may require adjustment or correction to more accurately reflect absolute core temperature with respect to determining accurate clinical thresholds relative to the expected normal temperature for the time of day observed. Further investigation into the utility and application of peripheral measurement of body temperature is warranted.
了解体温的昼夜节律对于解释单次体温测量结果和评估动物的生理状态非常重要。在开发用于家畜远程测温的微创工具方面，能够在身体外周部位测量体温也可能非常重要。本研究旨在调查外周部位测量的体温在多大程度上反映了常用的核心测量值（阴道温度），以及绵羊体温的昼夜节律性，以期在广泛的绵羊生产系统中实际应用。将外周温度感应微芯片（LifeChip®）植入 11 只杂交母羊的胸锁乳突肌（颈部）横向和尾部皮下。将 iButton®温度记录仪置于阴道内以记录核心体温测量值（Tv）。颈部（Tn）和尾部（Tt）的外周体温测量值与核心部位测量值 Tv 有显著差异（P<0.05），Tn 低于 Tv，Tt 低于 Tv 和 Tn。在重复测量分析中，全天在 Tv、Tn 和 Tt 之间观察到昼夜节律模式相似，Tv 和 Tn 之间的差异时间短（从 1400 到 1600 小时），Tv 和 Tt 之间的差异时间长（从 1000 到 2100 小时）（P<0.05）。这些结果表明，颈部肌肉温度测量可能有助于检测绵羊核心体温的昼夜节律模式，但可能无法准确反映绝对核心温度。外周测量值可能需要调整或校正，以更准确地反映相对于观察到的一天中的时间的预期正常温度的绝对核心温度。需要进一步研究外周体温测量的实用性和应用。
