|Hart, Richard - RETIRED ARS|
Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 25, 2005
Publication Date: September 1, 2005
Citation: Derner, J.D., Hart, R.H. 2005. Heifer performance under two stocking rates on fourwing saltbush-dominated rangeland. Rangeland Ecology and Management.58(5):489-494. Interpretive Summary: Use of rangeland dominated by fourwing saltbush (Atriplex canescens [Pursh] Nutt), a nutritious shrub, during the winter season may be an alternative for livestock producers instead of providing supplemental hay, energy and protein feedstuffs to their animals. This practice would also extend the grazing season and provide opportunities for additional animal gain via grazing, but there is a lack of information concerning stocking rates and animal gains. Yearling heifers had a greater gain per head per day with light compared to moderate stocking rates when grazing in late fall or early spring, but gain per unit land area was similar for both stocking rates. Land managers with rangeland containing fourwing saltbush should consider using these pastures during the late fall or early spring using light stocking rates to lengthen the grazing season with economic benefits resulting from lowered feed costs and adequate individual animal gains.
Technical Abstract: The efficiency of livestock production in shortgrass steppe may be increased by grazing fourwing saltbush (Atriplex canescens [Pursh] Nutt) -dominated rangeland in late fall and/or early spring, but there is a paucity of information concerning stocking rates and animal gains. The objective of this study was to compare the effects of light (5 yearling Hereford heifers) and moderate (8 heifers) stocking rates on weight gains of yearling heifers grazing replicated 16-ha pastures dominated by fourwing saltbush in a late-fall (November to mid January) from 1996 to 1998 and an early spring grazing period (April to mid May) from 1996 to 1999. Average daily gain (ADG, kg·hd-1·d-1) was 58% greater for light (0.65 ± 0.06, mean ± 1SE) compared to moderate (0.41 ± 0.05) stocking rates in the late fall grazing period, and 115% greater with light (0.59 ± 0.06) than moderate (0.27 ±0.07) stocking rates in the early spring grazing period. Beef production (kg gain·ha-1) did not differ, however, between stocking rates for either the late fall (16.4 ± 3.9 vs. 17.4 ± 4.5, light vs. moderate stocking rates) or early spring (9.6 ± 2.7 vs. 7.6 ± 4.8) grazing periods. We suggest that land managers employ light stocking rates in both the early spring and late fall grazing periods to obtain adequate individual animal gains without sacrificing gains per unit land area. Climatic events such as excessive snowfall and years with below-average precipitation will dampen animal performance, however. Lengthening of the grazing season in the shortgrass steppe should be economically desirable to land managers as feed costs could be lowered and animal gains obtained through minimal input.