Browsing Journal of Range Management, Volume 48, Number 3 (May 1995) by Subjects
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Grain supplementation on bluestem range for intensive-early stocked steersA 4-year study was conducted on Kansas Flint Hills bluestem range to monitor animal gain, grass, and forb standing biomass following grazing, plant population dynamics, and in 2 years, subsequent feedlot performance of steers under intensive-early stocking supplemented with increasing levels of sorghum grain. Each year from 1988 through 1991, crossbred beef steers were stocked at 0.24 ha/100 kg of initial steer weight from 5 May to 1; July. Steers in twice-replicated pastures were given no supplementation, 0.91 kg rolled sorghum grain per head daily, or 1.82 kg rolled sorghum grain per head daily, which corresponded to approximately 0, 0.3, and 0.6% of body weight-1. All steers were implanted with estradiol 17 beta in 1988 and zeranol in 1989-91 during initial processing and had unlimited access to a lasalocid/mineral mixture during the entire trial. In 1989 and 1990, representative groups of steers selected from all treatment/pasture combinations were subjected to a feedlot finishing phase and carcass data were obtained. Grass and forb standing crops were estimated each year at livestock removal in mid-July and again in early October. Pretreatment species composition and basal cover were determined in 1988 and compared to those at the end of the study. In mid-July, when cattle were removed, residual standing biomass of grass increased in direct proportion to increasing level of supplement. Standing biomass of grass at the end of the growing season did not differ among pastures with different supplement levels. Forb standing biomass did not differ among pastures with different supplement levels in July or October. Changes in plant populations among treatments during the course of the study were minimal. During the early portion of the grazing period, sorghum grain supplementation did not significantly influence steer gains, but average daily gain during the latter part of the grazing period increased in direct proportion to increasing level of sorghum grain supplement. Daily gain. feed intake, carcass characteristics, and gain:feed ratio were not different among treatments during the feedlot phase. Although conversion efficiencies may be economically marginal, low-level grain supplementation has the potential to increase the daily gain of cattle grazing early-season tallgrass prairie under an intensive-early stocking program.
Herbage dynamics on 2 Northern Great Plains range sitesQuantity and quality of forage produced are primary determinants of level of livestock production derived from grazing lands. Moreover, species composition of herbage is often considered a primary determinant of the ecological condition of rangelands. The broad objective of this study was to quantify the productivity, growth dynamics, and quality of herbage growing on 2 Northern Great Plains range sites and to concurrently relate magnitude and composition of production to the ecological condition of the sites. Using frequent harvest techniques, the 2-year study showed herbage production on the highly productive silty range site averaged 219 g m-2 as compared to 218 g m-2 on the supposedly less productive clay pan range site. The primary reason the clay pan site proved to be as productive as the silty site was attributed to the greater amounts of introduced annual grasses on the clay pan (148 g m-2) than the silty site (104 g m-2). The annual grass component on the clay pan was a near equal mix (71 vs 51 g m-2) of Japanese brome (Bromus japonicus Thunb.) and cheatgrass (B. tectorum L.) whereas the overwhelming dominant on the silty site was cheatgrass (73 g m-2). Western wheatgrass [Pascopyrum smithii Rydh. (Love)] was the dominant perennial grass on both sites averaging 49 g m-2 on the clay pan site and 57 g m-2 on the silty site. There were minimal differences between sites in terms of nutrient quality values (i.e., crude protein, acid detergent fiber, neutral detergent fiber) with results showing clearly that age of tissue was the major factor altering seasonal forage quality values. Range condition analyses revealed the clay pan site was in fair ecological condition and the silty site was in good condition. Study results demonstrate the need for land management agencies to continue to refine productivity estimates as well as adopt new techniques for assessing the ecological condition of rangelands.