• Flushing Ewes on Chemically Cured Hill Pastures

      Tart, D. L.; Sharrow, S. H. (Society for Range Management, 1982-07-01)
      A study was conducted to evaluate the use of chemically cured pasture as a flushing feed for ewes in western Oregon. In 1976 paraquat (0.28 kg/ha) was used to chemically cure hill pasture forage when perennial ryegrass (Lolium perenne L.) and tall fescue (Festuca arundinacea Schreb.) were in early anthesis. Crossbred ewes grazed the pastures from 17 days after the start of mating. Forage available during the breeding season had a higher protein content (P<.50) on paraquat-treated than on untreated pasture. Paraquat treatment had no effect, however on forage dry matter digestibility (P<.05). Chemical curing greatly reduced herbage yield, probably due to increased shattering and decomposition losses. Summer rainfall may have intensified the latter problem. Using chemically cured forage as flushing feed did not improve ewe live weight gains or lambing performance over untreated forage. Therefore, flushing ewes on chemically cured pasture appears to have little potential in areas, such as western Oregon, where summer rainfall is likely to occur.
    • Sheep as a biological control agent for tansy ragwort

      Sharrow, S. H.; Mosher, W. D. (Society for Range Management, 1982-07-01)
      Tansy ragwort (Senecio jacobaea) is a biennial weed commonly found on forest and pasture lands in the maritime regions of the Pacific Northwest. Pyrrolizidine alkaloids in tansy ragwort, when consumed by most types of livestock, produce progressive and irreversible liver damage. Sheep, however, appear immune to these alkaloids. To evaluate the possibility of using sheep to suppress tansy ragwort in cattle pastures, 100 plants were marked and their status followed during 1977 and 1978 in pastures grazed by cattle alone and in pastures grazed by both cattle and sheep. Total tansy ragwort mortality did not differ between pastures. However, the cause of mortality did differ. Mortality on the cattle-grazed pasture was predominately due to completion of the plant's biennial life cycle (blooming and seed set), while most plant mortality on the sheep plus cattle pasture appeared to be the result of grazing. The data suggest that sheep may be used as a biological control agent to suppress tansy ragwort populations by reducing their ability to produce seed.