Welsh Georgia E, Hancock Serina N, Ding Luoyang, Blache Dominique, Maloney Shane K
College of Environmental and Life Sciences, School of Agriculture, Murdoch University, Murdoch, Western Australia, 6150, Australia.
School of Human Sciences, Anatomy and Physiology, The University of Western Australia, Crawley, Western Australia, 6009, Australia.
J Anim Sci. 2025 Jan 4;103. doi: 10.1093/jas/skaf368.
In ruminants, water ingestion causes an immediate and measurable decline in rumen temperature. While this physiological response is well established, its application for estimating water intake has not previously been investigated. This study assessed the suitability of a thermodynamic modelling approach to estimate water intake in sheep using intra-ruminal temperature data. A fluid calorimetry equation was first validated under controlled laboratory conditions, then applied to data from six sheep fitted with intra-ruminal temperature loggers. Animals were offered water of known volume and temperature, and intake estimations were calculated using the temperature drop, baseline rumen temperature, water temperature, and estimated rumen volume based on liveweight. To improve volume estimation, additional rumen volume and liveweight data from a separate group were used to generate a generalised prediction equation for rumen volume. The approach underestimated the volume of water consumed, and so we developed a correction factor to account for physiological variation in the effective rumen volume at the time of drinking. Using the effective rumen volume in calculations resulted in estimated intake volumes that generally aligned with the measured values (P < 0.01). Our results demonstrate that measured changes in intra-ruminal temperature can be used to estimate water intake, offering a promising tool for precision livestock monitoring in extensive grazing systems.
在反刍动物中，饮水会导致瘤胃温度立即出现可测量的下降。虽然这种生理反应已得到充分证实，但其在估计水分摄入量方面的应用此前尚未得到研究。本研究评估了一种热力学建模方法利用瘤胃内温度数据估计绵羊水分摄入量的适用性。首先在可控的实验室条件下验证了一个流体量热方程，然后将其应用于六只安装了瘤胃内温度记录器的绵羊的数据。给动物提供已知体积和温度的水，并根据温度下降、基线瘤胃温度、水温以及基于体重估计的瘤胃体积来计算摄入量估计值。为了改进体积估计，使用来自另一组的额外瘤胃体积和体重数据生成了一个瘤胃体积的广义预测方程。该方法低估了所消耗的水量，因此我们开发了一个校正因子来解释饮水时有效瘤胃体积的生理变化。在计算中使用有效瘤胃体积导致估计摄入量总体上与测量值相符（P < 0.01）。我们的结果表明，瘤胃内温度的测量变化可用于估计水分摄入量，为粗放放牧系统中的精准家畜监测提供了一种有前景的工具。
