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.

中文翻译：

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短毛羊体温的核心和外围部位测量

了解体温的昼夜节律对于解释单个体温测量值和评估动物的生理状态非常重要。在外围位置测量体温的能力对于开发用于牲畜远程温度测量的微创工具也很重要。本研究旨在调查在外围部位测量的体温如何反映常用的核心测量值（阴道温度）和绵羊体温的昼夜节律，以期在广泛的绵羊生产系统中实际应用。11 只杂交母羊被植入外周温度传感微芯片 (LifeChip®)，其横向放置在胸锁乳突肌（颈部）肌肉和尾部皮下。iButton® 温度记录器被放置在阴道内以记录核心体温测量值 (Tv)。在颈部 (Tn) 和尾部 (Tt) 周边部位观察到的体温测量值与在核心部位 Tv 测量的体温测量值显着不同 (P < 0.05)，Tn 低于 Tv，Tt 低于 Tv 和 Tn . 在重复测量分析中，全天观察到 Tv、Tn 和 Tt 之间昼夜节律模式的相似性，Tv 和 Tn 之间存在短期差异（从 1400 到 1600 小时），而 Tv 和 Tt 之间存在长期差异（从1000 至 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温度的昼夜节律模式，但可能无法准确反映绝对核心温度。外围测量可能需要调整或校正，以更准确地反映绝对核心温度，从而确定相对于观察到的一天中的时间的预期正常温度的准确临床阈值。有必要进一步研究外周体温测量的效用和应用。外围测量可能需要调整或校正，以更准确地反映绝对核心温度，从而确定相对于观察到的一天中的时间的预期正常温度的准确临床阈值。有必要进一步研究外周体温测量的效用和应用。外围测量可能需要调整或校正，以更准确地反映绝对核心温度，从而确定相对于观察到的一天中的时间的预期正常温度的准确临床阈值。有必要进一步研究外周体温测量的效用和应用。