Noseband sensor validation and behavioural indicators for assessing beef cattle grazing on extensive pastures

Authors: Raynor, Edward; Derner, Justin; Soder, Kathy; Augustine, David

Submitted to: Applied Animal Behaviour Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2021
Publication Date: 7/22/2021
Citation: Raynor, E.J., Derner, J.D., Soder, K.J., Augustine, D.J. 2021. Noseband sensor validation and behavioural indicators for assessing beef cattle grazing on extensive pastures. Applied Animal Behaviour Science. 242:1-30. https://doi.org/10.1016/j.applanim.2021.105402.
DOI: https://doi.org/10.1016/j.applanim.2021.105402

Interpretive Summary: Monitoring grazing behavior of free-ranging ruminants such as cattle is critical to evaluate the relationship between animal nutrition and the environment. This information is important to improve utilization of pasture and rangeland, meet nutrient needs of animals, and maintain or improve ecosystem services. While current technologies to monitor feeding behavior have been used in confinement (indoor) settings, they have not been evaluated in an extensive rangeland situation. Our objectives were to: 1) compare grazing behavior recorded by a noseband sensor to visual observation; and 2) evaluate the noseband sensor in two distinct plant communities that varied in sward height and leaf angle. Our results showed that the noseband sensor was highly correlated to observed grazing behavior, and that results were more accurate in swards with upright stems and leaves when compared to a lawn-like prostrate sward. The noseband sensor performed reliably and accurately under long-term (28-day) grazing studies without minimal need for human intervention that could bias results. The noseband sensor is useful on-animal sensor technology for research that demands long-term grazing behavior information across diverse pasture and rangeland environments.

Technical Abstract: Advances in sensor technologies to monitor animal location and activity have enhanced the ability to study foraging decisions of free-ranging herbivores. Sensors that monitor jaw movements to quantify ingestion behaviours, such as the RumiWatch (RW) noseband sensor system, have primarily been used in indoor housing systems or structurally homogeneous, small pasture (paddock) environments. Continuously monitoring these behaviours in extensive and heterogeneous semiarid rangelands has not been conducted. We evaluated the accuracy of the RW noseband sensor system to record grazing behaviour for two grazing seasons in 130-ha pastures (paddocks) composed of native, mixed-species plant communities. The noseband sensor was evaluated against direct visual observations of yearling steers grazing within two different experiments. First, the time duration of grazing and grazing bout starts and finishes recorded by the sensor were compared to direct visual observation data (Experiment 1). A high correlation (rs = 0.95) for hourly grazing time resulted between the RW system and visual observations. Second, we examined the ability of the RW system to measure grazing bite rates in distinct plant communities that varied in height and leaf angle (Experiment 2). The accordance between direct observation and measurement by the RW system for bite rate improved from 2019 (Concordance Correlation Coefficient (CCC) = 0.71) to 2020 (CCC = 0.80) after modifications to improve the fit of the halter supporting the noseband sensor. Correlations between the sensor and visual observations increased by ~17% with this modification for grazing bouts in mixed-species and midgrass-dominated swards; correlations remained ~10% lower in shortgrass-dominated swards. Our results indicate that the RW noseband sensor is a reliable technology for monitoring free-ranging cattle grazing activity and quantifying bite rates in a heterogeneous rangeland ecosystem, but that bite rate measurements are more accurate in swards with vertically oriented stems and leaves compared to lawn-like prostrate swards. When coupled with global positioning system (GPS) devices, such sensors have the potential to quantify where, when and at what rate herbivores access forage in variable landscapes. Such metrics can then be used to relate foraging behaviour to animal performance. Similarly, improved understanding of how herbivores shape vegetation dynamics, ecosystem processes, and patterns often entails knowledge of forage utilization within an area across time, rather than merely the number of herbivores and their distribution. This investigation indicates that the RW noseband sensor system is a useful on-animal sensor technology for research that demands sustained herbivore ingestion measurements across mixed-species forage environments.