Effect of protein supplementation on forage utilization by cattle in annual grass-dominated rangelands in the Channel Scablands of Eastern Washington

Authors: Stonecipher, Clinton - Clint; Panter, Kip; VILLALBA, JUAN - Utah State University

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/13/2016
Publication Date: 6/1/2016
Publication URL: https://handle.nal.usda.gov/10113/62861
Citation: Stonecipher, C.A., Panter, K.E., Villalba, J.J. 2016. Effect of protein supplementation on forage utilization by cattle in annual grass-dominated rangelands in the Channel Scablands of Eastern Washington. Journal of Animal Science. 94(6):2572-2582.

Interpretive Summary: Medusahead (Taeniatherum caput-medusae [L.] Nevski) is an annual grass replacing native vegetation in the shrub-steppe habitat of eastern Washington. Livestock typically avoid grazing medusahead and forage alternatives are becoming limited in the region. A study was conducted to determine if supplementing grazing cattle with crude protein would help increase the consumption of medusahead during the summer months after it matured. The percentage of medusahead in the pastures decreased over two years of grazing. There was no difference in consumption of medusahead between supplemented and non-supplemented cattle the first five days of grazing, however consumption of medusahead increased in the protein supplmented cattle during days six through 10 of the grazing periods. The effect of grazing on medusahead abundance suggest cattle may be utilized to graze this weed after it has matured in an integrated management program with other forms of control to reduce infestation prior to seeding with desirable forage species.

Technical Abstract: Medusahead (Taeniatherum caput-medusae [L.] Nevski) has become a major component replacing vegetation on the Channeled Scablands of eastern Washington. Livestock typically avoid grazing medusahead and forage alternatives are becoming limited in the region. We hypothesized that protein supplementation would provide a nutritional context that complements the nutritional composition of medusahead. Thus, we predicted that protein supplementation would allow cattle to increase use of medusahead over non-supplemented control animals. Cattle grazed medusahead-infested rangeland for 10-d periods during June, July, and August over two consecutive years. Eight separate pastures were grazed, by cattle pairs, during each of the three grazing periods. Cattle in four control pastures received no supplement and four pastures received a supplement of canola meal that supplied 75% of the daily recommended crude protein requirement. Bite counts were used to determine diet composition. Forage categories consisted of annual grasses, perennial grasses, and forbs. Bites taken of annual grasses were similar between treatment groups during the first 5-d of the grazing period (P>0.05) and then cattle supplemented with meal increased consumption of annual grasses during d 6 to 10 (P<0.05). Consumption of annual grasses was greater during the second year of the grazing study (P<0.05) likely due to a decline in abundance of forage alternatives in the plant community. The percentage of medusahead in the annual grass forage class tended to decrease in pastures grazed by treatment groups over years (P=0.056). The percentage of medusahead in the annual grasses was similar across the study in non-grazed pastures (P>0.05). However, the percentage of medusahead in the annual grasses decreased in the supplemented and non-supplemented grazed pastures for the same years, 87+4.2%, 64+3.6%, and 50+3.6%, respectively. Forb availability was greatest the first year of grazing and declined the second year of grazing and continued to decline the following year with no grazing (P<0.05). Perennial grass availability was low throughout the study. The effects of grazing on medusahead abundance suggest cattle may be utilized to graze this weed after it has matured in an integrated management program with other forms of control to reduce infestation prior to seeding with desirable forage species.