Location: Rangeland Resources & Systems ResearchTitle: Does pulse-grazing influence within- and between-grazing season dietary quality of yearling steers in shortgrass steppe?
Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 10/31/2017
Publication Date: 2/9/2018
Citation: Plechaty, T.R., Scasta, J., Derner, J.D., Augustine, D.J. 2018. Does pulse-grazing influence within- and between-grazing season dietary quality of yearling steers in shortgrass steppe?. Society for Range Management Meeting Abstracts. Abstract Proceedings of the 71st Society for Range Management, Technical Training, and Trade Show. Jan 28 - Feb 2, 2018, Sparks, NV.
Technical Abstract: Pulse-grazing, high stock density with short grazing periods (weeks) followed by long (months to > 1 year) rest periods, is a grazing management strategy posited to decrease preferential selection by cattle and increase utilization of forage, but influences on dietary quality of grazing animals in shortgrass steppe are widely unknown. We used the experimental framework of the participatory, stakeholder-led Collaborative Adaptive Rangeland Management (CARM) project at the USDA Central Plains Experimental Range to compare effects of pulse grazing to traditional rangeland management (TRM) on weekly dietary quality (based on fecal NIRS) of yearling steers for a 20-week grazing season (mid-May to early October) for two years (2015 and 2016). Pulse grazing employed the same moderate seasonal stocking rate as TRM, but stocking density was ten-fold higher (1.85 vs. 0.185 steers per ha), and livestock were adaptively rotated among 10, 130 ha pastures within the grazing season. Across the grazing season, crude protein in cattle diets was 26-31% greater for TRM than pulse-grazing in 2015 (TRM 9.7 ± 0.6%, pulse-grazing 7.4 ± 0.5 %, mean ± 1 SE) and 2016 (TRM 8.6 ± 0.5 %, pulse-grazing 6.8 ± 0.2 %). Digestible organic matter was also greater for TRM than pulse-grazing in 2015 (TRM 62.4 ± 0.3 %, pulse-grazing 61.0 ± 0.4 %) and 2016 (TRM 64.0 ± 0.8 %, pulse-grazing 62.4 ± 0.8 %). Within grazing season diet quality differences were greater between pulse-grazing and TRM early in the season (mid-May through June), with these differences becoming less as the growing season progressed. Adaptive management decision-making for dietary quality with pulse-grazing should address use of prescribed burning to increase early grazing season forage quality, matching mid- and late-season use of pastures with local precipitation patterns and amounts, and likely quicker rotations through pastures during rapid vegetation growth periods.