Tobin Colin T, Bailey Derek W, Stephenson Mitchell B, Trotter Mark G
Department of Animal and Range Sciences, New Mexico State University, Las Cruces, NM 88003, USA.
Panhandle Research and Extension Center, University of Nebraska-Lincoln, Scottsbluff, NE 69361, USA.
Animals (Basel). 2021 Sep 8;11(9):2635. doi: 10.3390/ani11092635.
Proper grazing management of arid and semi-arid rangelands requires experienced personnel and monitoring. Applications of GPS tracking and sensor technologies could help ranchers identify livestock well-being and grazing management issues so that they can promptly respond. The objective of this case study was to evaluate temporal changes in cattle association patterns using global positioning system (GPS) tracking in pastures with different stocking densities (low stocking density [LSD] = 0.123 animals ha, high stocking density [HSD] = 0.417 animals ha) at a ranch near Prescott, Arizona. Both pastures contained similar herd sizes (135 and 130 cows, respectively). A total of 32 cows in the HSD herd and 29 cows in the LSD herd were tracked using GPS collars at location fixes of 30 min during a 6-week trial in the summer of 2019. A half-weight index (HWI) value was calculated for each pair of GPS-tracked cattle (i.e., dyads) to determine the proportion of time that cattle were within 75 m and 500 m of each other. Forage mass of both pastures were relatively similar at the beginning of the study and forage utilization increased from 5 to 24% in the HSD pasture and increased from 10 to 20% in the LSD pasture. Cattle in both pastures exhibited relatively low mean association values (HWI < 0.25) at both spatial scales. Near the end of the study, cattle began to disperse likely in search of forages ( < 0.01) and travelled farther ( < 0.01) from water than during earlier periods. Real-time GPS tracking has the potential to remotely detect changes in animal spatial association (e.g., HWI), and identify when cows disperse, likely searching for forage.
对干旱和半干旱牧场进行适当的放牧管理需要有经验的人员和监测。应用全球定位系统（GPS）跟踪和传感器技术可以帮助牧场主识别牲畜的健康状况和放牧管理问题，以便他们能够及时做出反应。本案例研究的目的是在亚利桑那州普雷斯科特附近的一个牧场，利用全球定位系统（GPS）跟踪技术，评估不同载畜密度（低载畜密度[LSD]=0.123头/公顷，高载畜密度[HSD]=0.417头/公顷）牧场中牛群关联模式的时间变化。两个牧场的牛群规模相似（分别为135头和130头奶牛）。在2019年夏季为期6周的试验中，使用GPS项圈以30分钟的定位间隔对高载畜密度牛群中的32头牛和低载畜密度牛群中的29头牛进行了跟踪。为每对GPS跟踪的牛（即二元组）计算半权重指数（HWI）值，以确定牛彼此相距75米和500米以内的时间比例。在研究开始时，两个牧场的牧草量相对相似，高载畜密度牧场的牧草利用率从5%增加到24%，低载畜密度牧场的牧草利用率从10%增加到20%。两个牧场的牛在两个空间尺度上的平均关联值都相对较低（HWI<0.25）。在研究接近尾声时，牛群开始分散，可能是为了寻找草料（P<0.01），并且比早期离水源更远（P<0.01）。实时GPS跟踪有潜力远程检测动物空间关联的变化（例如HWI），并识别奶牛何时分散，可能是在寻找草料。
