Evaluating Methods of Estimating Forage Intake by Grazing Cattle

Two methods of estimating forage intake of grazing cattle were compared to clipped estimates in 4-pasture rotational grazing systems on Sandhills subirrigated meadow from mid-May through early August over a 4-year period. Clipping standing vegetation samples within a pasture before and after cattle grazing provides for an accurate estimate of forage removal during a grazing period. A less laborious method of intake estimation commonly used is based on a percentage of an animal’s liveweight. University Extension and some federal agencies use a 2.3% factor and others such as the Natural Resources Conservation Service use a 2.7% factor. In this study on a Sandhills subirrigated meadow, the 2.3% of body weight intake factor appropriately matched the clipping estimates in 63% of the evaluations. In contrast, the 2.7% of body weight factor provided similar estimates to the clipping estimate in only 38% of the evaluations. This implies that the 2.3% estimate more accurately represents forage intake of beef cattle and has less chance of overestimating cattle intake. Allocation of surplus forage to grazing cattle reduces harvest efficiency, reduces beef production per acre, and negatively effects profitability of beef operations

Spring Meadow Management Practices: What’s a Rancher to do?

• Subirrigated meadows are a valuable forage resource to ranching operations in the Nebraska Sandhills, being used for both hay production and livestock grazing. • The water table of these meadows is within one meter of the soil surface during the growing season. • In some years, wet conditions hinder meadow utilization, resulting in a buildup of standing dead and litter plant material which can lower forage production. • Investigate if burning and mowing are effective strategies to remove dead plant material from meadows • Determine if burning or mowing interact with grazing to influence end of season forage production Burning or mowing effectively removes dead plant material from meadows with no later loss in forage production. Burning and mowing do not interact with grazing to influence later forage production. Spring grazing acted independently to significantly lower end of season forage production. Conclusions • Ranchers can use burning or mowing to effectively remove dead plant material from subirrigated meadows in the Nebraska Sandhills with no later losses in forage production (Fig.1 & Fig.2). • On the other hand, spring grazing reduces end of season forage production (Fig.3). Therefore, caution should be used with spring grazing if a rancher’s goal is to maximize hay yields from meadow forage

Evaluation of Plant- waxes to Estimate Forage Intake in Grazing Cattle

Although key to the efficiency of a cattle operation, feed intake is challenging to evaluate in a grazing setting. However, even within forage- based systems, plant- wax markers may be used to predict dietary choices and feed intake. Plant- waxes are a complex mixture of lipids found on the surface of plants. When sufficiently unique among plants, the composition of diets can be determined from the pattern of these compounds in the forages ingested. These markers were used to delineate the parts of the corn plant and, separately, 8 western rangeland grasses and legumes. Using plant waxes, the components of the corn plant were clearly distinguished. Th is technique therefore could be useful in a monoculture, such as a corn residue field, to determine the plant parts predominating in the diet. Delineating plants in a complex sward was more difficult, particularly among like species. Th e use of more markers may help to more explicitly distinguish plants within diverse pastures, such as western rangelands

Cattle Grazing Effects on \u3ci\u3ePhragmites australis\u3c/i\u3e in Nebraska

Phragmites australis (common reed) is one of the most widely distributed flowering plants in North America. The introduced lineage occurs in wetland and riparian areas covering a range of climatic types. In Nebraska, an abundance of livestock could help to reduce P. australis with proper timing and grazing intensities. In 2011, a 3-yr study was initiated to evaluate targeted cattle grazing and herbicide effects and the nutritive value of this species. Treatments included a single application of imazapyr (Habitatt, BASF Corporation, Research Triangle Park, NC) herbicide applied in the first year, grazing, and a control. Grazing was applied for up to five consecutive days in June and August 2011 and 2012 and in June 2013. Stem density, height, and biomass of P. australis were determined before each grazing period and in 2014. Diet samples were collected from rumenally fistulated steers each grazing period. Imazapyr provided 100% control of P. australis; however, re-establishment began 2 yr post-treatment. Grazing significantly reduced pregrazing P. australis biomass in the second and third growing season (P \u3c 0.05). Stem density and height in the grazed treatment was similar to the control through 2012; however, in 2013 and 2014, control stem density was 1.5 times greater and height was 1.4 times that of the grazed treatment. Crude protein content of diet samples was greater in 2011 (16.8%) compared with 2012 (14.3%, P \u3c 0.05). In vitro dry matter digestibility (IVDMD) of diet samples (45.4%) was not affected by year or month (P \u3c 0.05). The relatively low IVDMD suggests that some form of energy supplementation would be needed to create a better nutritional balance. The cumulative effect of grazing does have the potential to reduce P. australis populations, but other methods would have to be used for greater control and site restoration

Plant Community Patterns on Upland Prairie in the Eastern Nebraska Sandhills

Topography is an important factor in determining vegetation patterns in grasslands. We collected frequency of occurrence data from transects on dune tops, south-facing slopes, north-facing slopes, and interdunal valleys in the eastern Sandhills of Nebraska to determine the effect of topographical position on plant species composition. We used canonical discriminant analysis to separate the four topographical positions based on frequency of occurrence of the 18 principal planttaxa. Topographic position played an important role in plant distribution on upland prairie with interdunal transects strongly separated from transects on other topographical positions. Bluegrasses (Poa L. spp.), switchgrass (Panicum virgatum L.), and white sage (Artemisia ludoviciana Nutt.) were highly associated with interdunal valleys. Little bluestem [Schizachyrium scoparium (Michx.)] and cool-season grasses, such as needlegrasses (Stipa L. spp.) and Junegrass [Koeleria pyramidata (Lam.) Beauv.], tended to be associated with north-facing slopes and warm-season grasses, such as prairie sandreed [Calamovilfa longifolia (Hook) Scrihn.] and sand bluestem (Andropogon hallii Hack.), tended to be associated with south-facing slopes. Sedges (Carex L. spp.), western ragweed (Ambrosia psilostachya DC.), and Scribner dichanthelium [Dichanthelium oligosanthes (Schult.) Gould var. scribnerianum (Nash)] were the most common taxa occurring over all topographic positions. Aspect proved to be an important factor in influencing vegetation distribution in the eastern Sandhills of Nebraska

Risk Implications from the Selection of Rainfall Index Insurance Intervals

Since the passage of the 1994 Crop Insurance Reform Act, the federal crop insurance program has grown in both size and scope. The program progressed from generating under $1 billion in premiums in 1994 to generating nearly$9.3 billion in 2016 (USDA-RMA 1994, 2016b). In 2007, the federal crop insurance program introduced the Rainfall Index (RI) and Vegetation Index (VI) Insurance Pilot Program for Pasture, Rangeland, and Forage (PRF) in selected states. In 2016, RI-PRF replaced VI-PRF and was made available in all 48 contiguous states enrolling 28,538 policies and providing over a billion dollars in coverage on more than 52.3 million acres (USDA-RMA 2016b). However, insured acreage represents only about 8% of the total 649.5 million acres of pasture and hay land. This small percent of coverage contrasts greatly to corn, where 87% of acres were insured in 2016 (USDA -RMA 2016c)

Impacts of 40 Years of the Gudmundsen Sandhills Laboratory on Beef Cattle and Range Systems

The University of Nebraska (UNL) Gudmundsen Sandhills Laboratory (GSL) is a 12,800-acre research ranch in the Nebraska Sandhills. In 1978, Elmer “Pete” and Abbie Gudmundsen gifted the former Rafter C Ranch to the University of Nebraska Foundation. Thus, 2018 was the 40th year of UNL oversight of GSL. To the credit of UNL Administration, GSL development for range livestock research was delegated to a team of Research and Extension Specialists chaired by Dr. Don Clanton. Other members of that original team were Jim Nichols, Range Science; Gene Deutscher, Reproductive Physiologist; Dick Clark, Agricultural Economist; and Ivan Rush, Beef Extension Specialist. This team configured the ranch to investigate production and management questions pertinent to the region

Monitoring Climate Impacts on Annual Forage Production across U.S. Semi-Arid Grasslands

The ecosystem performance approach, used in a previously published case study focusing on the Nebraska Sandhills, proved to minimize impacts of non-climatic factors (e.g., overgrazing, fire, pests) on the remotely-sensed signal of seasonal vegetation greenness resulting in a better attribution of its changes to climate variability. The current study validates the applicability of this approach for assessment of seasonal and interannual climate impacts on forage production in the western United States semi-arid grasslands. Using a piecewise regression tree model, we developed the Expected Ecosystem Performance (EEP), a proxy for annual forage production that reflects climatic influences while minimizing impacts of management and disturbances. The EEP model establishes relations between seasonal climate, site-specific growth potential, and long-term growth variability to capture changes in the growing season greenness measured via a time-integrated Normalized Difference Vegetation Index (NDVI) observed using a Moderate Resolution Imaging Spectroradiometer (MODIS). The resulting 19 years of EEP were converted to expected biomass (EB, kg ha-1 year-1) using a newly-developed relation with the Soil Survey Geographic Database range production data (R2= 0.7). Results were compared to ground-observed biomass datasets collected by the U.S. Department of Agriculture and University of Nebraska-Lincoln (R2 = 0.67). This study illustrated that this approach is transferable to other semi-arid and arid grasslands and can be used for creating timely, post-season forage production assessments. When combined with seasonal climate predictions, it can provide within-season estimates of annual forage production that can serve as a basis for more informed adaptive decision making by livestock producers and land managers

Forum: Critical Decision Dates for Drought Management in Centraland Northern Great Plains Rangeland

Ranchers and other land managers of central and northern Great Plains rangelands face recurrent droughts that negatively influence economic returns and environmental resources for ranching enterprises. Accurately estimating annual forage production and initiating drought decision-making actions proactively early in the growing season are both critical to minimize financial losses and degradation to rangeland soil and plant resources. Long-term forage production data sets from Alberta, Kansas, Montana, Nebraska, North Dakota, South Dakota, and Wyoming demonstrated that precipitation in April, May, and June (or some combination of these months) robustly predict annual forage production. Growth curves from clipping experiments and ecological site descriptions (ESDs) indicate that maximum monthly forage growth rates occur 1 mo after the best spring month (April to June) precipitation prediction variable. Key for rangeland managers is that the probability of receiving sufficient precipitation after 1 July to compensate for earlier spring precipitation deficits is extremely low. The complexity of human dimensions of drought decision-making necessitates that forage prediction tools account for uncertainty in matching animal demand to forage availability, and that continued advancements in remote sensing applications address both spatial and temporal relationships in forage production to inform critical decision dates for drought management in these rangeland ecosystems