Stocker Cattle Response to Grazing Management in Tallgrass Prairie

Abstract

The effects of stocking rate and grazing method on performance of yearling beef cattle grazing tallgrass prairies in north-central Oklahoma were evaluated from 1989 to 1994. Pastures dominated by big bluestem [Andropogon gerardii Vitman], little bluestem [Schizachyrium scoparium (Michx.) Nash], and indiangrass [Sorghastrum nutans (L.) Nash], were allocated to either short duration rotational or continuous stocking methods and stocking rates ranging from 52 animalunit-days (AUD) ha-1 to 90 AUD ha-1. Steers grazed the units from late April to late September. Precipitation was above average during the study period. Live weight gain per head was higher under continuous stocking than rotational stocking at all stocking rates. At 52 AUD ha-1 , individual gains under rotational stocking were 11% less than under continuous stocking. At 90 AUD ha-1 , individual gains under rotational stocking were decreased by 20%. Measurements of steer diets and forage standing crop suggest the reduction in weight gain was due to reduced forage intake under rotational stocking. Live weight gain per hectare increased with stocking rate and was higher with continuous stocking at all stocking rates. Net returns per hectare increased as stocking rate increased for both stocking methods but were lower for rotational stocking at all stocking rates. Variable costs per head would have to decrease by 24 to 34% under rotational stocking to equalize net returns between the 2 grazing methods. Unless the decline in gain per head can be reduced or eliminated, there is no economic incentive to implement rotational stocking under the conditions of this study.

Rangelands, Volume 22, Number 1 (February 2000)

“…In the tall grass prairie of Oklahoma, standing crop of forage averaged 16% higher under short-duration compared to continuous grazing (3,200 vs. 2,760 lbs acre-') (Cassels et al 1995). However, it was later reported that this was not due to greater plant vigor under short-duration grazing but rather higher forage intake by steers under continuous grazing (McCollum et al 1999). In north-central Texas herbage growth dynamics did not differ between short-duration and continuous grazing (Heitschmidt et al 1987b) or between 14 versus 42 paddock short-duration grazing (Heitschmidt et al 1987a).…”

“…A careful analysis of these 10 studies indicates small or no difference in livestock productivity between short-duration and continuous grazing if stocking rates are equal with one exception. McCollum et al (1999) found live weight gains of yearling cattle were 11 to 20% lower under short-duration than season long grazing when averaged across six levels of stocking. This was caused by lower forage intake of cattle under short-duration grazing (McCollum and Gillen 1998).…”

“…Four studies have shown short-duration grazing has lowered individual livestock productivity compared to continuous or season-long grazing (Parker et al 1987, Anderson 1988, Heitschmidt et al 1990, McCollum et al 1999. Another 5 studies showed no difference between short-duration and continuous grazing (Jung et al 1985, Pitts and Bryant 1987, Olson and Malechek 1988, Taylor et al 1993, Manley et al 1997) while 1 study showed short-duration grazing increased livestock productivity (Daugherty et al 1982).…”

“…Considerable information is available on short term impacts (1-4 years) of short-duration grazing on soils, vegetation, and livestock. However, there are only 4 studies in North America that have evaluated longer term vegetation, livestock, and financial outcomes under short-duration grazing (Heitschmidt et al 1990 February 2000et al 1993, Manley et al 1997, McCollum et al 1999. Generally, we consider these long term studies to be well designed and implemented.…”

“…Lower individual animal productivity under shortduration grazing is the primary explanation why it gave inferior net returns compared to season-long grazing in south-central Oklahoma (McCollum et al 1999). …”