Submitted to: Annual Biomedical Research Conference for Minority Students
Publication Type: Abstract only
Publication Acceptance Date: 9/1/2003
Publication Date: 10/17/2003
Citation: Pedro, A.F., Northup, B.K., Brown, M.A., Biles, C.A., Dawkins, D. 2003. Utilization of Bermudagrass (Cynodon dactylon) pastures by yearling heifers: Behaviors, patterns and reasons [abstract]. Annual Biomedical Research Conference for Minority Students. Paper No. E150. p. 344. Interpretive Summary: ABSTRACT ONLY
Technical Abstract: Available forage and nutrients are heterogeneously distributed and could affect grazing distribution. This paper described how Brahman-influenced yearling heifers utilized 2.0 ha bermudagrass (Cynodon dactylon) pastures in different condition (poor, low production units; good, moderate production units) during June-July 2003. Pastures were divided into 35x35 m grid cells, and cattle (n=3, poor condition; n=4, good condition) were assigned to pastures and allowed unencumbered access for the entire grazing period. Cattle behaviors were observed during morning (0700-1000) grazing bouts at 10-minute intervals, and used to describe the most-grazed cells on a weekly basis. These cells were sampled to define availability, species composition, nitrogen content, and dry matter digestibility of forage. One animal per pasture was fitted with global positioning system (GPS) collar to record locations (15-minute intervals), and the information used to develop interpolated maps of weekly pasture utilization. Cattle on good condition pasture spent less time grazing (P<0.05) and more ruminating and socializing than on poor condition units. Cattle displayed distinct preferences for the southern halves of pastures during morning grazing periods regardless of accumulated grazing pressure, forage availability or quality. Weekly pasture utilization was neither uniform nor consistent. Some parts of the pastures were heavily preferred while other areas were rarely utilized, and changed only slightly with accumulated grazing pressure. Results indicated use of bermudagrass pastures was affected by multiple factors, including some unrelated to pasture condition or forage characteristics. Wind direction, pasture slope, and locations of neighboring cattle affected behavior and served as drivers of grazing pattern.