Newsroom: Optimizing cattle grazing, a review!

A team of UC Davis researchers have recently published an interdisciplinary review about strategies used to optimize grazing distribution of cattle on rangeland. Authors of this review represent the fields of animal behavior (Maggie Creamer and Kristina Horback), agricultural economics (Tina Saitone), and plant science (Leslie Roche). 

Grazing distribution refers to how cattle are dispersed when foraging on expansive and complex swaths of grazeable lands called rangeland. Rangeland accounts for greater than 50% of land cover in the western United States, and depending on specific descriptions, rangelands cover approximately 80% of earth [1]. Achieving uniform grazing distribution on these landscapes is an enormous challenge faced by ranchers who manage cattle grazing on rangeland. Grazing patterns can impact various ecosystem services, water quality, wildfire spread, vegetation and animal health, environmental sustainability, and ranch profitability. Thus, achieving optimal grazing distribution is a timely and relevant issue in a world faced by rapid population growth demands, consumer demands for sustainably-sourced food, and declining resource availability for agriculture.

Upon reviewing the literature, researchers found that there is a dichotomy between management strategies to optimize grazing distribution where some strategies manipulate an aspect of the animal’s environment (adjusting grazing pressure in a location, targeted grazing by providing artificial water sources) while others manipulate an aspect of the animals themselves (animal training, spatial cognition, selecting for certain behavior, etc.) [see table 1]. Relatively few studies integrated or compared more than one strategy within a manipulation type, and it was especially rare that a study integrated or compared across manipulation types (animal vs. environmental).  Importantly, most of these studies provided absolutely no economic cost-benefit analysis of implementing grazing management, an element that is crucial for ranchers to decide to adopt certain management strategies. It is likely that to optimize grazing distribution, researchers need to design studies that integrate or compare across manipulations, since finding a solution is likely site-specific and requires multiple types of management interventions (since complex problems often need complex solutions).

Animal ManipulationsEnvironmental Manipulations
Select for individual animal traitsAdjust stocking rate (grazing pressure), stocking density, and/or timing (e.g., season) of grazing
Select for herd characteristics (e.g., age, breed)Alter vegetation (e.g., prescribed burning, fertilization practices)
Rear young cattle to specific sites to encourage development of preferred terrain useUse salt/mineral supplement type or placement
Low-stress herding Implement and maintain off-stream water sources or shade
Virtual fencing (i.e. associative learning principles)Use permanent fencing (to contain or exclude animals)
Table 1. Examples of animal and environmental manipulation management strategies used to optimize cattle distribution.

In order to investigate the paucity of integration of information between behaviorists, rangeland scientists, and economists, the review authors created a co-authorship network of authors contributing to this topic. Co-authors were identified by a systematic search of key literature. This resulted in a sparse network of authorship and identified a notable disconnect between the fields of animal behavior, animal production, rangeland science, and economics. This disconnect was especially evident between animal behavior authors and authors from all other fields. The co-authorship network provides a potential explanation for the lack of integration of strategies that is seen in current literature and encourages authors to work across disciplines to solve this urgent and relevant grazing distribution problem.

The colored dots, or nodes, represent each individual author and the color variation delineates author fields of expertise (right). The lines connecting the authors, called edges, represent co-authorship on a given paper.  

References:

[1] Lund, H. G. (2007). Accounting for the world’s rangelands. Rangelands, 29(1), 3-10.

For more information:

*Creamer, M. L., Roche, L. M., *Horback, K. M., & Saitone, T. L. (2020). Optimising cattle grazing distribution on rangeland: a systematic review and network analysis. The Rangeland Journal, 41(5), 441-455.

*Stars denote ABGG/UCD affiliated authors

Cover Photo Source: Dave Young

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