Submitted to: International Journal of Food, Agriculture, and the Environment
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/28/2005
Publication Date: 4/1/2005
Citation: Taylor, J.B., Seefeldt, S.S., Thelen, T.M. 2005. The use of short-duration intensive sheep grazing to increase sheep utilization of leafy spurge (Euphorbia esula L.). Journal of Food, Agriculture and Environment. 3(2):323-326. Interpretive Summary: Short-duration intensive sheep grazing results in rapid and substantial utilization of leafy spurge. As grazing density increases and duration decreases, sheep utilized more of the leafy spurge plants that were flowering. Shorter duration sheep-grazing strategies allow for more flexibility in terms of when grazing is applied. As such, a producer may shift annual grazing events to avoid repeated and associated use of desired plants at critical stages when targeting leafy spurge infestations.
Technical Abstract: Leafy spurge (Euphorbia esula L.) is an exotic plant that invades and ultimately degrades North American rangeland ecosystems. The use of short-duration intensive grazing management strategies to manipulate sheep utilization of leafy spurge was investigated. A 0.6-hectare leafy spurge-infested (cover =75%) area was divided into six 0.1-hectare pastures. During June 2002, 2003 and 2004, 36 nonpregnant Targhee breed ewes (2 to 3 years old) grazed the pastures (6 ewes/pasture) at a rate of 480 sheep days/hectare. Three pastures were continuously grazed with ewes for eight days (8-day; moderate-density continuous). The remaining three pastures were subdivided into 0.025-hectare subdivisions, and all ewes grazed each individual subdivision for two days and were rotated among all four subdivisions over an eight-day period (2-day; high-density rotational). Before-grazing leafy spurge stem densities were similar between years (P = 0.18; 249 vs. 207 and 213 ± 17 stems/m2 for 2002, 2003, and 2004, respectively) and grazing treatments (P = 0.69; 226 vs. 228 ± 17 stems/m2 for 8- and 2-day treatments, respectively). In 2004, the 2-day grazing treatment caused more (P = 0.04) utilization of leafy spurge flowering stems than did the 8-day grazing treatment (24.0 vs. 14.6 ± 2.2 flower stems utilized/m2, respectively). Regardless of treatment, 69 to 70% of the leafy spurge plants were utilized but 57 to 61% of the total vegetative biomass remained standing at the end of the grazing periods. Within the context of this experiment, sheep managed in short-duration intensive grazing systems substantially grazed the standing leafy spurge. As grazing density increased and duration decreased, ewes utilized more leafy spurge-flowering stems. The 2-d rotational high-density sheep grazing strategy may provide greater long-term effectiveness in controlling leafy spurge infestations.