Some effects of a rotational grazing treatment on cattle preference for plant communities

Rotational grazing is commonly assumed to improve livestock distribution compared to continuous grazing, but little evidence supports this contention. Research was conducted on the effects of rotational grazing (RG) compared to continuous grazing (CC) on the preference of cattle for plant communities. Diffeant livestock densitiea in the RG treatments were created by varying the size of paddocka in a 465_ha, l&paddock, cell designed RG treatment stocked al a rate of 3.6 ha/cow/yr. Paddock sizes of 30 and lo-ha were used to simulate RG with 14 (RG-14) and 4Zpaddocks (RE 42), respectively. The CG treatment consisted of a 24&ha pasture stocked at 5.9 ha/cow/yr. Data consisted of hourly daylight observations of cattle location and activity during 8 seasonal trials lasting 6-15 days. These data were expressed as a percent of the time cattle were observed in each of 4 plant communities and the area surrounding permanent water. Relative electivity (RE), a preference index, and a selectivity index (SI) that measures departures from random distribution were calculated from these data. Relative electivity (i.e., preference) for plant communities was not affected by grazing treatment. However, cattle were leas selective for plant communities as livestock density decreased from the RG-42 to the CG treatment. In the RG14 treatment, the cattle were either unaffected or less selective on the last day than on the first day in a paddock. We hypotbeaize that grazing systems influence cattle preference for plant communities by affecting the availability of forage biomass per unit land area rather than by their effect on grazing pressure.