Acoustic analysis: A novel way to measure livestock grazing behavior

Acoustic analysis: A novel way to measure livestock grazing behavior

Summary

Though the summer grazing trial will not take place until May-August 2015, progress was made in preliminary testing of the methodology. All techniques, besides GPS tracking systems, were determined to be successful in accomplishing their role. Because of the inaccuracy of the GPS tracking systems, observations or enhanced post-processing differential correction will need to take the place of or augment these systems in the future study. All devices and supplies have been purchased and are ready for deployment as soon as the study begins.

Objectives/Performance Targets

1. Develop and apply novel acoustic monitoring systems to quantify lamb grazing behavior in terms of prehensive biting events and rumination; 
2. Quantify lamb body temperatures diurnally; 
3. Determine diurnal behavior (and shade utilization in silvopastures) using GPS tracking systems and remote sensing technology; and 
4. Integrate information on forage quantity and quality with spatial and temporal information on grazing behavior and body temperatures to understand the effects of silvopasture systems on animal performance.

Accomplishments/Milestones

The acoustic recording system was successfully tested on some ewe lambs to log about 16 hours of wideband recordings. Preliminary testing with the software, SIGNAL and GRASS, found a 95% correlation with visual bite counts.

The vaginal temperature loggers were successfully deployed on ewe lambs; a nonlinear, mixed-effects model of the temperature data was prepared in R. Preliminary results indicate, as expected, that sheep in the open pasture systems are hotter and their diurnal body temperatures fluctuate at a greater scale than sheep in the silvopasture systems.

The GPS tracking system was tested, but the inaccuracy was found to exceed 2.5 m. Thus, an observation-based approach to determining shade utilization or an alternative approach to differential correction of the GPS data is currently being sought. A sampling of trees was measured and their shade canopies were mapped for analysis over time. Once a reliable method of determining sheep location is realized, the sheep location data can be collected and then analyzed using this temporal shade map.

The 12 week summer grazing study will take place in mid-May through mid-August of 2015. Protocol sheets are being written for each procedure to ensure that all necessary data is collected properly. Virginia Tech Institutional Care and Use Committee approved the general protocol for the entire study.

Impacts and Contributions/Outcomes

The information gained from this research will engage livestock producers in the benefits of silvopasture systems to livestock well-being and system productivity. It will also aid in optimizing silvopasture system function by understanding the mechanisms for animal shade utilization and intake as a function of shade presence. The techniques that are utilized in this project can be duplicated by other researchers studying ruminant behavior in a free-range setting.