UC Davis

Consistent individual differences (CIDs) in animal behavior can be measured in assays that target specific behaviors which are assumed to represent underlying stable traits. These are linked to various outcome measures, such as how animals use space and/or forage in natural environments. Consistent individual behavioral variation in beef cattle has been previously studied, however, traditional assays involve stressful contexts, subjective rating scales, and short-term assessments. CIDs measured in multidimensional behavior assays with extensively managed beef cattle have not yet been linked to grazing patterns by previous studies. The grazing patterns of beef cattle that forage on extensive rangeland landscapes have implications for the environmental sustainability of cattle production and conservation of rangeland ecosystems. The objectives of this dissertation were to measure CIDs in behavior in cattle using broad scope, yet practical, assays and investigate how these relate to relevant feeding behaviors (Chapter 1), identify consistent grazing patterns of cattle on rangeland (Chapter 2), and examine the relationship between CIDs measured in assays and grazing patterns (Chapter 3). I found that cattle showed consistency in behaviors observed across short-term and long-term time frames in a management context (handling cows through an open chute) without using physical restraint (Chapter 1). Behaviors measured in distinct locations of the assay loaded onto different principal components (e.g. time to traverse the concrete chute while isolated and time to traverse the hydraulic squeeze chute while isolated), which may indicate different mechanisms from which these behaviors arise. Less active and less excitable cows during the assay chose to feed from supplement rather than be in proximity to groupmates in a social-feed tradeoff task (Chapter 1). Individual cows were consistent in grazing patterns across two summers despite cattle having access to a new, high-elevation watering site during the second summer of grazing the same rangeland pasture (Chapter 2). This provides evidence that consistent individual differences in grazing are robust and persist between two years and despite a management tool (off-stream water) added to the rangeland environment, which is a commonly used method to achieve better distribution of cows. Cows that were using higher elevation and were further from water were also more variable in their elevation and distance from water, thus behavioral flexibility coincides with overall rangeland use patterns in cattle (Chapter 2). Ultimately, cattle that appeared more cautious and passive in the narrow cement chute while isolated were those that were grazing higher elevation areas, further from water, and closer to upland supplement sites (Chapter 3). This could signify that cows that have a reactive (also called a passive) response when coping with mildly stressful contexts (i.e. isolation and handling) also notice environmental fluctuations over the grazing season and respond by grazing wider and higher, less utilized areas of the pasture. These passive cows are thought to be using the rangeland more sustainably (or optimally) because they are not clumping near water resources or preferred grazing areas, but rather grazing vegetation that is more difficult to travel to and may otherwise go under-grazed. Altogether, temperature was the most influential animal or environmental factor on grazing patterns; cows conserved energy by not traveling as far or on high elevation and prioritized being closer to water and resting sites on hotter days or weeks (Chapter 2 and 3). Neither grazing patterns nor behaviors exhibited during the management context assay related to cows’ approach to a novel feeding opportunity (Chapters 1 and 3). This dissertation (a) informs the design and utilization of behavior assays for identifying CIDs in beef cattle (Chapter 1), (b) fills literature gaps in how management tools used to optimize cattle distribution alter grazing patterns of individual cows (Chapter 2), and (c) demonstrates the potential to select cattle that exhibit certain behaviors (i.e. more passive cows) to shape a herd with more desirable grazing patterns (i.e. use higher elevation areas further from water; Chapter 3).