Cattle Diets and Performance: Enhancing What We Know with Advanced Plant DNA Technology

View the project final report

Commodities

• Additional Plants: native plants
• Animals: bovine

Practices

• Animal Production: grazing management, grazing - continuous, grazing - rotational, range improvement
• Education and Training: extension, participatory research
• Sustainable Communities: local and regional food systems, partnerships

There is longstanding debate in the field of rangeland management about the perceived benefits of a rotational or adaptive grazing system utilizing higher stock density and shorter grazing periods in a pasture or paddock. The belief that rotational or adaptive grazing can reduce animal selectivity, increase carrying capacity, improve plant productivity, and increase species composition has led ranchers to adopt this strategy. Unfortunately, the scientific research has not found a positive correlation between rotational grazing and the benefits ranchers claim to incur (Briske et al. 2008; Teague et al. 2008). The functional mechanism driving differences between grazing systems are the management induced diets of cattle. Understanding how these diets are driven is paramount to resolving this debate and assisting ranchers in reaching production and conservation goals. The goal of this research is to provide ranchers with an accurate assessment of the differences in cattle nutrition, which is a function of what cattle eat, in an adaptive rotational grazing management strategy compared to a traditional continuous season-long grazing strategy. Ultimately, this will quantify the production and conservation trade-offs associated with each system in northern-mixed grass prairie and shortgrass steppe ecosystems. The funding will allow us to use the novel DNA metabarcoding analysis of fecal samples to discern, with a high level of accuracy, the diet composition of cattle to the plant genus or species level. This information will be coupled with Near Infrared Spectroscopy (NIRS) for nutritional performance (Lyons and Stuth 1992), and high resolution pedometers for animal activity for which we already have financial support. By collecting this data using new and detailed technology, the impact of grazing strategy on animal nutrition and behavior will give ranchers a better decision-making tool when deciding what grazing strategy will help them meet their operation objectives. Our project will move beyond anecdotes and provide quantitative data of the latest technological insight into what cattle eats, why they eat it relative to grazing managmenet, and how it influences animal performance. Research will be presented at Wyoming Extension events, the American Society of Animal Science annual meeting, stakeholder meetings, and the Society for Range Management annual meeting.

The overall goal of this research is to provide ranchers with a decision-making tool to implement a grazing system that will fit their individual operation goals.

1. To determine how grazing management strategy influences diet composition of yearling cattle at USDA ARS grazing experiments near Cheyenne, Wyoming and Nunn, Colorado. Specifically, does the diet of animals in an adaptive grazing management strategy contain more or different plant species than continuous season-long grazing strategy? Are animals consuming plants that are not considered to typically be eaten by cattle?

2. Quantify how cattle diet composition correlates with nutritional plane and performance data derived from NIRS (such as crude protein and digestibility)? In other words, how do the specific plants that are in the diet correlate to crude protein and digestibility levels, and ultimately, daily gains.

3. Determine how the diet of yearling cattle eat relates to energy expenditures and activity levels in cattle in different grazing systems. Are animals in adaptive grazing management systems spending more time walking and looking for palatable plant species?