Effects of half-vs three-quarter-season grazing of native grass Effects of half-vs three-quarter-season grazing of native grass pastures pastures

Mixed-breed


Introduction
The cost of renting native grass and the economics of the stocker cattle business have dictated consideration of different grazing times and stocking rates.In addition, flexibility in marketing times also is needed to reduce risks associated with the volitality of the cattle market.Our purpose was to compare two grazing systems (1/2 season and 3/4 season) in terms of steer gains, steer economics, and the effect of grazing on grass compositions.

Experimental Procedures
Mixed breed steers (average starting weight = 563 lb) grazing native grass pastures were allotted each year (1990 to 1998) to either 1/2season or 3/4-season grazing systems.The 1/2season system entailed grazing from late April to July 15 (1 steer/2 acres, 81 days), and the 3/4season system entailed grazing from late April to August 15 (1 steer to 3 acres, 112 days).The pastures were burned every year except 1996, when only the east four pastures were burned because of dry weather.Four pastures were used per treatment per year.The steers were weighed individually at the start and end of the grazing periods.
To evaluate the economic returns, the various costs associated with each grazing system were compared.Direct costs per animal included start-up costs (drugs, veterinary, starter feed, trucking, processing labor), death loss, mineral, salt, and interest.Pasture costs included labor of looking after cattle on grass and cost of renting grass (Bluestem Pasture Report by Kansas Department of Agriculture).The monthly average prices for the weight range at Dodge City were adjusted to southeast Kansas prices.
The step point method (300 to 400 points per pasture) was used to take actual plant inventories (1990,1994,1998).The pastures were sampled each year after animals were removed and again in November by clipping small areas to determine how much dry matter remained compared to caged areas that excluded animals.

Results and Discussion
We observed a greater increase in Indiangrass (P<.05,Table 1) and a greater increase in percentage basal cover of perennial grass (P<.05) for 1/2-season grazing compared with 3/4-season grazing.Change in percent of total perennial grasses was the same for both systems after 9 years of grazing.Little bluestem declined (percentage of composition) in both grazing systems but was not different by system.Neither of the grazing systems had a negative effect on the grass composition.In the 3/4-season pastures, only 350 lb of dry matter per acre were produced after cattle were removed; in 1/2-season grazing pastures, 1,100 lb of dry matter were produced per acre.
The steers that grazed the 1/2-season pastures for 81 days gained faster (2.78 vs. 2.48 lb per day, P<.01) than the steers that grazed the 3/4-season pastures for 112 days.However, allowing the steers to graze until August 15 resulted in more total pounds gained per animal (278 lb vs 225 lb; Table 2).
The 1/2-season grazing system had the highest return per acre ($33.31/acrevs $29.98/acre).The 3/4-season grazing had the highest return/animal ($30.61vs $23.75, Table 3).The economic desirability of a particular system will depend on the perspective of the individual producer.For example, producers who own both land and cattle likely will prefer the 1/2-season grazing.
However, the producers who own cattle but rent pasture and hire labor likely will favor the 3/4-season grazing system because of cattle costs and the additional total gain.However, this analysis considers only selling cattle at the end of the grazing period.If cattle are owned and graze on other forages prior to native grass or owned during the feedlot phase, this could change the overall view of the economic desirability of a particular system.

Table 2 . Effect of Grazing System on Ani- mal Performance (9-Yr Summary)
Means in the same row with unlike superscripts are different (P<.01).