Grazing dynamics of cattle stocked at heavy rates in a continuous and rotational grazed system

The relationships between grazing patterns of cattle and sward characteristics under two divergent grazing methods, continuous (CG) and rotational (RG) grazing, were determined in grassland sites of a Post Oak ( Quercus stellata ) woodland in Texas from April to November 1981. Year-long rate of stocking in both grazing methods was equivalent at 50% above levels normally used to sustain stock without winter hay. Grazing time per unit area and grazing frequency on 0.1-ha plots within 3 grassland sites in each grazing regime were measured over a 7-month growing season using time-lapse photography. The pasture characteristics measured included forage standing crop and percentage of area grazed. Grazing system did not effect standing crop until the latter half of the growing season, when animals in the CG reduced grazing time on observed communities and used alternative habitats. Animals on RG grazed on 0.1-ha grassland sites 2–3 days per month while similar CG grassland sites were grazed 8–16 days per month at 3–6 day intervals. When grazed, the RG grassland sites experienced approximately 3 times more daily grazing events than CG with each grazing event varying from 55±11 to 345±31 animal-minutes and from 35±7 to 76±13 animal-minutes in RG and CG, respectively. The RG grassland sites received 4–21 and 21–35 more animal-hours per month in the first and second halves of the growing season, respectively, than CG. Care must be exercised in designing RG systems to ensure that grazing on seasonally preferred habitats can be controlled to allow strategic access to nutritionally critical habitats.