2010 Annual Report
1a.Objectives (from AD-416)
Specific objectives of this research include:
Objective 1. Provide management guidelines to improve the conservation and enhancement of agroecosystem function and structure in grasslands of the NGP.
Objective 2. Improve the viability of cattle production on the NGP by providing management strategies that increase the efficiency of forage utilization.
Objective 3. Develop methods to alter the composition of beef so that it better meets the emerging market demand for healthier beef.
1b.Approach (from AD-416)
An automated rainout shelter will be used to simulate drought conditions and test if early-season water stress and (or) defoliation following water stress will have greater impact on productivity of switchgrass or western wheatgrass or on mixtures of western wheatgrass and alfalfa. The influence of soil attributes on growth characteristics of perennial grasses will be determined with greenhouse evaluations using soil collected under native vegetation and under severely weed invaded plant communities at four sites between Mandan, ND and Pierre, SD. Field-based estimates of the greenhouse gases carbon dioxide and nitrous oxide will be used to determine if soil emissions of nitrous oxide offset carbon uptake by moderately grazed mixed-grass prairie. Satellite-based estimates of plant canopy carbon:nitrogen ratio will be determined for five native rangeland pastures and these estimates will be used to determine if they can be used to estimate forage quality for pastures on the northern Great Plains. Experiments with cattle will be conducted to determine if supplemental fat and ruminally undegradable protein will improve feed efficiency of grazing cattle, and if supplemental fat that is fed to forage-finished cattle can increase carcass quality and concentration of unsaturated fatty acids in beef. Trials with cattle will also be conducted to determine if grazing higher quality forages with supplemental flaxseed and (or) forages containing condensed tannin will result in reduced methane emissions per unit of beef produced and greater economic returns. Other trials with cattle will be conducted to determine if omega-3 fatty acid levels in beef can be raised substantially if fattening yearlings are fed flaxseed or flaxseed oil that is treated to protect the alpha-linolenic acid in it from hydrogenation by ruminal microbes. Finally, experiments with fistulated and normal cattle will be conducted to determine if restricting dietary intake of forage and supplemental unsaturated fat will not slow growth but will increase the level of unsaturated fatty acids in beef.
For Subobjective 1.1, the second year of precipitation regime was initiated and data collected. For Subobjective 1.2, soil sampling was finished and plants are in greenhouse. Soil analysis and plant data collection was finished and data analysis has begun. For Subobjective 2.1, data analysis is being done and a manuscript may be submitted this year although the responsible scientist has left ARS. For Subobjective 3.1, an in vitro trial was completed to evaluate modifications of the flaxseed treatment to determine if one of more of the treatment modifications can reduce rumen microbial biohydrogenation of the omega-3 fatty acid in flaxseed.
Ingestion of condensed tannin in water to reduce methane emissions of ruminant livestock. It has been shown that intake of some types of condensed tannins by sheep, cattle, and goats can reduce their emissions of methane by as much as 30%. However, many commonly grazed or fed forages do not contain condensed tannins and livestock grazing high quality forage will often not consume solid supplemnents that could contain condensed tannin. However, since grazing livestock usually drink it may be possible to supplement their diets with condensed tannin if they will drink water containing small amounts of condensed tannin. ARS scientists at Mandan, North Dakota evaluated this approach and concluded that ruminant livestock will ingest small amounts of condensed tannin via their drinking water. Therefore, this approach may be a practical way to put methane-reducing condensed tannin into grazing livestock.
Effect of supplemental ground flaxseed to beef cattle grazing summer range. Supplementing energy sources such as grain is problematic because growth response differs with the type of energy supplement, but feed use efficiency has been improved by supplementing vegetable oil or oilseeds such as soybean or corn oil or whole soybeans. ARS scientists at Mandan, North Dakota supplemented grazing cattle with ground flaxseed (another type of oilseed) and found that daily weigh gain and feed use efficiency was improved by supplementing flaxseed. These results suggest that supplementing cattle during summer grazing with flaxseed could be beneficial to producers who wish to increase livestock growth rates.
Shrubs in northern grasslands increase carbon and nitrogen in soil. Overgrazing and fire suppression have contributed to an increased abundance of shrubs within grasslands throughout the world. Increases in shrubs have come at the expense of grasses, and little is known about how this shift in vegetation dominance will affect grassland ecosystems. ARS scientists in Mandan, North Dakota conducted a study to determine the influence of shrub expansion on soil carbon and nitrogen in a northern mixed-grass prairie grassland near Mandan, North Dakota. They found that carbon and nitrogen was greater under established shrubs as compared to grassland in the surface six inches of soil. Accumulation of soil carbon and nitrogen under shrubs in northern grasslands may contribute to ‘islands of fertility’, which can have long-term impacts on ecosystem functions.
5.Significant Activities that Support Special Target Populations
Scientists at NGPRL are part of a project between North Dakota State University, Sitting Bull College and ARS that is evaluating the interest in members of the Standing Rock community in initiating a ‘Natural Beef’ enterprise and assisting Tribal members in sustaining their natural resource base. The location scientists will evaluate the impact of prairie dogs on soil and vegetation.
Scholljegerdes, E.J., Kronberg, S.L. 2010. Effects of Supplemental Ground Flaxseed Fed to Beef Cattle Grazing Summer Native Range on the Northern Great Plains. Journal of Animal Science. 88:2108-2121.
Springsteen, A., Loya, W., Liebig, M.A., Hendrickson, J.R. 2010. Soil carbon and nitrogen across a chronosequence of woody plant expansion in North Dakota. Plant and Soil. 328: 369-379.
Kronberg, S.L. 2010. Sheep Intake of Water Containing Quebracho or Black Wattle Tannin. Rangeland Ecol. Manage. 63:258-262.