Poop and pedometers: What cattle really do on the range

Authors: PLECHATY, TAMARAH - University Of Wyoming; SCASTA, J. DEREK - University Of Wyoming; Derner, Justin

Submitted to: Popular Publication
Publication Type: Popular Publication
Publication Acceptance Date: 12/20/2016
Publication Date: 7/11/2017
Citation: Plechaty, T., Scasta, J., Derner, J.D. 2017. Poop and pedometers: What cattle really do on the range. Popular Publication. Cow Country Summer 2016. pg. 6.

Interpretive Summary:

Technical Abstract: Cattle serve as energy brokers between cellulose in plant biomass and energy and protein available for human consumption. Despite the global significance of cattle to society for livelihood, culture and meat production, a key question remains for nutrition of these ruminants: does grazing management influence diet selection? Recent technological advances provide opportunities to more effectively assess diet selection in free-ranging cattle on rangelands. For both rangeland ecosystems (northern mixed-grass prairie and shortgrass steppe), dietary quality –using crude protein as the response variable – was greater in the continuous, season-long grazing strategy across the grazing season than the adaptive rotational grazing management strategy. This higher diet quality in the continuous season-long grazing strategy (for both rangeland ecosystems and for both years 2015 – a year with higher than average growing season precipitation – and 2016 – a year with lower than average growing season precipitation) resulted in yearling cattle in this grazing strategy gaining more weight over the growing season (10-15% more) than animals in the adaptive rotational grazing strategy. Most people know that cattle eat grass, but we have found some interesting results when looking at the differences in dietary protein composition across different grazing management strategies. Cattle actually eat more forbs and the annual grass six-weeks fescue (Vulpia octoflora) early in the grazing season in the continuous season-long grazing strategy; conversely cattle in the adaptive rotational grazing strategy selectively preferred a western wheatgrass (Pascopyrum smithii)/six-week fescue combination. We also found that cattle in the continuous season-long grazing strategy eat less western wheatgrass and more blue grama (Bouteloua gracilis) towards the end of the grazing season, whereas cattle in the adaptive rotational grazing strategy consistently exhibit a high proportion of the dietary protein composition from western wheatgrass across the grazing season. We used pedometers (Fitbits for cattle!) on cattle in each grazing strategy to collect data each second of the grazing season to provide very high temporal resolution of time spent lying down, standing, how many steps are taken and a motion index. Our preliminary results indicate that the two grazing strategies did not influence cattle behavior and animal energetics using the pedometer data. However, when we compared step count to crude protein levels in the diet, differences did emerge between grazing strategies. When dietary crude protein levels were high (> 8.5%), cattle in the continuous season-long strategy tended to take more steps compared to when crude protein levels were low (< 8.5%). When crude protein levels were lower (< 8.5%), step counts did not differ between the grazing strategies. As forage quality declines, we hypothesize that cattle in both grazing strategies are unable to exhibit sufficient dietary selectivity as additional expenditure of energy, in the form of more steps, is not compensated by the probability of ingesting higher quality forage.