Foraging behavior, botanical composition, and quality of beef cattle diets on burned versus unburned foothill rangelands

Authors: KLUTH, JANESSA - Montana State University; DAVIS, NOAH - Montana State University; WYFFELS, SAMUEL - Montana State University; MARLOW, CLAYTON - Montana State University; Vermeire, Lance; SITZ, TAYLRE - Montana State University; HAMILTON, THOMAS - Montana State University; DELCURTO, TIM - Montana State University

Submitted to: Grasses
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2025
Publication Date: 2/17/2025
Citation: Kluth, J., Davis, N., Wyffels, S., Marlow, C., Vermeire, L.T., Sitz, T., Hamilton, T., Delcurto, T. 2025. Foraging behavior, botanical composition, and quality of beef cattle diets on burned versus unburned foothill rangelands. Grasses. 4(1). Article 8. https://doi.org/10.3390/grasses4010008.
DOI: https://doi.org/10.3390/grasses4010008

Interpretive Summary: Current management paradigms suggest deferring grazing rangeland for two years post-fire to avoid additional stress on native grass species, but there is little research supporting these recommendations. This study was conducted within and adjacent to the burn area of a wildfire to evaluate the differences in diet quality, botanical composition, and foraging behavior of beef cattle on burned and unburned rangeland in the spring and fall of the year following a fire. Diet composition and diet samples were collected during 20-minute bite-count periods using six ruminally cannulated cows in burned and unburned sites in June and September. Diets differed between burned and unburned sites across seasons, but differences were most apparent in June. Cattle grazed more selectively on burned sites in June, consuming a higher quality diet dominated by forbs. In September, cattle shifted to grass-dominated diets with fewer differences between burned and unburned sites. This indicates that the nutritional flush on post-fire rangelands may be minimized by the end of the first growing season post-fire. Additionally, in the first spring post-fire, cattle may shift grazing pressure away from vulnerable perennial native grass species to the early-seral forbs, commonly associated with the post-fire environment.

Technical Abstract: Current management paradigms suggest deferring grazing rangeland for two years post-fire to avoid additional stress on native grass species, but there is little research supporting these recommendations. This study was conducted within and adjacent to the burn area of a wildfire to evaluate the differences in diet quality, botanical composition, and foraging behavior of beef cattle on burned and unburned rangeland in the spring and fall of the year following a fire. Diet composition and masticate samples were collected during 20-minute bite-count periods using six ruminally cannulated cows in burned and unburned sites in June and September. Diets differed between burned and unburned sites across seasons, but the differences were most apparent in June. Cattle grazed more selectively on burned sites in June, consuming a higher quality diet dominated by forbs. In September, cattle shifted to grass-dominated diets with fewer differences between burned and unburned sites. This indicates that the nutritional flush on post-fire rangelands may be minimized by the end of the first growing season post-fire. Additionally, in the first spring post-fire, cattle may shift grazing pressure away from vulnerable perennial native grass species to the early-seral forbs, commonly associated with the post-fire environment.