Burnett Tracy A, Kaur Manveen, Polsky Liam, Cerri Ronaldo L A
Applied Animal Biology, Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, Canada.
Front Vet Sci. 2020 Dec 16;7:597512. doi: 10.3389/fvets.2020.597512. eCollection 2020.
This study aimed to determine changes in rumen-reticular temperature (RRT) at estrus or ovulation and determine if these changes are associated with the intensity of estrous expression. Cows were equipped with an automated activity monitor (AAM) and a rumen-reticular bolus thermometer. A total of 190 estrus episodes were used where physical activity data was recorded using the AAM and ovulation was determined via ultrasonography of the ovaries at alert and twice daily, for a maximum of 60 h. Estrous expression was assessed using the maximum activity and duration in which activity remained above the AAM threshold; both characteristics were categorized using the median. Temperature data was collected for the duration of estrus, as well as for the interval of time where ovulation was determined to occur. Three measures of temperature were calculated: (1) positive area under the curve (AUC), (2) maximum positive temperature change (PTC), (3) maximum negative temperature change (NTC) at estrus (AUC/ PTC/ NTC) and around ovulation (AUC/PTC/ NTC). Both AUC and PTC were greater during estrus than around ovulation (2.7 ± 0.2 and 1.1 ± 0.3°C for AUC and AUC; 0.55 ± 0.03 and 0.26 ± 0.04°C for PTC and PTC, respectively). In contrast, NTC was lower around ovulation than estrus (-0.28 ± 0.05 and -0.60 ± 0.06°C for NTC and NTC). Cows with greater estrous expression had greater AUC and PTC during estrus than around ovulation, but cows with lesser estrous expression had similar AUC and PTC. Increases in AUC [High THI (Temperature Humidity Index): High activity: 4.7 ± 0.5, Low activity: 1.5 ± 0.4; Low THI: High activity: 3.1 ± 0.2, Low activity: 1.4 ± 0.2 °C] and PTC (High THI: High activity: 0.79 ± 0.08, Low activity: 0.36 ± 0.07; Low THI: High activity: 0.60 ± 0.04, Low activity: 0.47 ± 0.04°C) associated with estrous expression were found to be greater on days with higher THI. Alerts created using standard deviations from the mean were unable to detect estrus or ovulation with acceptable precision. Further research is required to determine how changes in RRT can be used successfully to predict estrus and ovulation.
本研究旨在确定发情期或排卵期瘤胃 - 网胃温度（RRT）的变化，并确定这些变化是否与发情表现强度相关。给奶牛配备了自动活动监测器（AAM）和瘤胃 - 网胃丸状温度计。总共使用了190次发情事件，其中使用AAM记录身体活动数据，并通过在出现警觉时以及每天两次对卵巢进行超声检查来确定排卵情况，最长持续60小时。使用最大活动量以及活动量保持高于AAM阈值的持续时间来评估发情表现；这两个特征均使用中位数进行分类。在发情期以及确定排卵发生的时间段内收集温度数据。计算了三种温度测量值：（1）曲线下正面积（AUC），（2）最大正温度变化（PTC），（3）发情期（AUC / PTC / NTC）和排卵前后（AUC / PTC / NTC）的最大负温度变化（NTC）。发情期的AUC和PTC均高于排卵前后（AUC分别为2.7±0.2和1.1±0.3°C；PTC分别为0.55±0.03和0.26±0.04°C）。相反，排卵前后的NTC低于发情期（NTC分别为 - 0.28±0.05和 - 0.60±0.06°C）。发情表现较强的奶牛在发情期的AUC和PTC高于排卵前后，但发情表现较弱的奶牛的AUC和PTC相似。在温度湿度指数（THI）较高的日子里，与发情表现相关的AUC（高THI：高活动量：4.7±0.5，低活动量：1.5±0.4；低THI：高活动量：3.1±0.2，低活动量：1.4±0.2°C）和PTC（高THI：高活动量：0.79±0.08，低活动量：0.36±0.07；低THI：高活动量：0.60±0.04，低活动量：0.47±0.04°C）的增加更为明显。使用与平均值的标准差创建的警报无法以可接受的精度检测出发情期或排卵期。需要进一步研究以确定如何成功利用RRT的变化来预测发情期和排卵期。
