W2012: Enhancing management, production, and sustainability of grazing ruminants in extensive landscapes

(Multistate Research Project)

Status: Inactive/Terminating

W2012: Enhancing management, production, and sustainability of grazing ruminants in extensive landscapes

Duration: 10/01/2014 to 09/30/2019

Administrative Advisor(s):

NIFA Reps:

Statement of Issues and Justification

The landscape and climate of the Western U.S. provide abundant range and agricultural lands suited to grazing and forage production, leading to a dominance of cow-calf and ewe-lamb systems in this region. The nutritional value of forages, particularly those grazed from rangeland, is highly variable in space and time, with nutrient quality and/or quantity often limiting optimum levels of livestock production. The development of scientifically sound nutritional management tactics for livestock in variable and often extensive conditions presents unique challenges to researchers. Increased knowledge of the mechanisms of herbivory, digestion, forage intake, and forage utilization can contribute to improved nutritional status and productivity of livestock, improved economic efficiency in forage-based livestock production systems, improved sustainability in ranching enterprises and revitalization of rural communities depending upon them.

A multitude of issues challenge livestock producers throughout the West, but maintaining economic viability is the most important. Improving the proportion of forage nutrients converted to animal products based on sound, science-driven management strategies is the most viable means of achieving improved biological efficiency. However, production systems that optimize livestock efficiencies cannot do so at the expense of the environment. Systems that concomitantly improve livestock and landscape responses need to be used. For example, tactics leading to increased conversion of nutrients to productive purposes in the animal also lead to reduced nutrient loading in air, soil, and water through decreased animal excretion of gases and underutilized nutrients. Additionally, understanding and controlling animal factors affecting herbivory and distribution of livestock in extensive environments adds to our ability to minimize animal impacts on the environment.

W-2012's goals are aligned with the USDA 2010-2015 Strategic Plan's Goals 1, 3, and 4. Specifically addressed by the project include Objective 1.3 (Support a sustainable and competitive agricultural system), Objective 3.2 (Enhance America's ability to develop and trade agricultural products derived from new technologies), and Objective 4.1 (Increase access to nutritious food). Our primary stakeholders are farmers, ranchers, and state and federal land managers in states represented by scientists participating in the project, but there is broad applicability of our work nation-wide. Our secondary stakeholders are the consumers of animal products that benefit from the reduced prices associated with efficient animal production systems. Our tertiary stakeholders are the citizens of communities whose economies are improved by profitable and sustainable animal industries and that benefit from the multiplier effects these industries have on community economies.

Limitations in predicting feed intake in extensive landscapes challenges our ability to manage resources and animal requirements. This project serves as a forum for development of collaborative studies and research projects that are complementary and work to solve issues associated with ruminant production in extensive landscapes. We seek to continue work in this area to develop methodologies to assess forage intake by grazing animals and development of scientifically sound nutritional management tactics for livestock in variable and often extensive conditions. Participation in this project has since its inception has involved scientists and extension specialist in the Western states including Arizona, Missouri, Montana, Nebraska, Nevada, New Mexico, North Dakota, Oregon, South Dakota, Utah, Washington, and Wyoming. We believe that the challenges that are shared among the Western states are best addressed by combining the expertise and resources from all the states. To our knowledge our project is unique and does not significantly overlap or duplicate other efforts currently underway by other multistate research projects or efforts within the USDA/ARS.

The focus of this Multistate Research Project is to contribute to our basic understanding of processes in (1) the plant-animal-landscape interface, (2) nutrient digestion and utilization from forages, (3) nutritional management strategies based on grazed or harvested forages and (4) methods to understand forage intake in grazing ruminants. The intent is to improve livestock digestive, metabolic, behavioral, production, and integrated system responses and to facilitate transfer of this information to users such as livestock producers and land managers both private and public. Continuous communication and collaboration among scientists working in this discipline can promote more rapid development and transfer of new knowledge related to sustainable livestock production from forage-based systems.

Related, Current and Previous Work

Most of the stations that are members of this collaborative agreement are located in the arid western states. Due to the relative paucity of vegetation in these states compared to those in other regions of the U.S., very different management techniques are necessary and this make this project unique from other multistate research projects.

Related current and previous research by members of W-1012 is based approached with the overall goal of enhancing ruminant production and sustainability in extensive landscapes. Studies reported herein, therefore, describe the effects of plane of nutrition and/or supplementation on ruminal fermentation, heifer development, performance, and grazing behavior. Work also reported by this group outlined nutrient intake response to range management practices, weaning systems and comparisons of feed intake using pen studies vs. range feed intake.

Accomplishments related to previous project outcomes and impacts:

The outcomes and impacts for the last 5 year period of this project are summarized below.

• 4th Grazing Livestock Symposium held July, 2010 in Estes Park, CO was organized, financially supported, and hosted by this group. There were 163 attendees from which 10 countries were represented. Attendee occupations included scientists, students, producers, and state/federal land managers. During the conference, 28 abstracts were presented and a peer-reviewed proceedings resulted and is available as a supplement to the Journal of Animal Science.

• Symposium was organized and hosted at the JAM 2013 titled “Nutrient requirements of the beef female in extensive grazing systems: Considerations for revising the beef NRC”. From this symposium 3 referred manuscripts were published and will be available to the NRC committee charged with revising the beef 1996/200 Nutrient Requirements for Beef Cattle. These manuscripts focused on protein, feed intake and energy utilization of cattle in extensive landscapes.

• A consistent methodology for n-alkane analysis was validated across laboratories in multiple states. As part of the validation, three forages were assessed: smooth bromegrass (Bromus inermis), switchgrass (Panicum virgatum) and red clover (Trifolium pretense). Ten mixtures were prepared containing 0%, 33.3%, 66.6% or 100% of a given forage. Based on the distinct n-alkane profiles of these individual forages, the botanical composition of the mixtures could be discerned. A thesis has been completed and 3 abstracts have been presented as a result of the work to validate the n-alkane method.

• The list of research achievements, publications, and student theses that are the product of the collaborative work of members of the Project is extensive. During the last 5 year period approximately 210 refereed publications, proceedings, and technical bulletins and 1 book chapter have resulted.

• Over the last 5 years, our members have participated extensively in and gave presentations yearly extension meetings, nutrition conferences, professional society sponsored national and regional meetings, and annual W-1012 meetings to promote the exchange of ideas, information and data.


  1. 1. Assess variation across space and time for n-alkane composition in unique classes of forages common to the Western United States, which is necessary for predicting feed intakes and diet choices of grazing ruminant animals.
  2. 2. Coordinate research and extension activities in extensive livestock production systems.
  3. Provide professional development and mentoring opportunities for committee participants, young scientists, stakeholders, and graduate students.


OBJ 1: Assessment of laboratory procedures for n-alkanes and determination of forage n-alkane profiles Advantages. Estimation of forage intake using n-alkane ratio has been found to be more precise than those obtained with chromium oxide and in vitro digestibility in both cattle (Oliveira et al., 2007) and sheep (Dove et al., 2000). Estimation of fecal output from a dosed marker and diet digestibility from in vitro incubation of diet samples has several disadvantages, ranging from inadequacy of the in vitro technique to problems associated with the estimation of fecal output (Dove and Mayes, 1996). The alkane method gives individual-animal intakes and can be used where animals are receiving feed supplements (Mayes and Dove, 2000). Also, gas chromatography (GC) analysis allows for both plant and dosed markers to be determined at the same time, which can limit analytical error bias. It is also not necessary to obtain absolute fecal concentrations, since a ratio of the concentrations in feces is used (Mayes and Dove, 2000). The use of controlled-release devices (CRD) of alkanes may also reduce measurement errors associated with diurnal and/or daily variations on fecal concentration of markers. However, unless fistulated, the CRD cartridge remains in the animal for life, and alkane release rates may not be consistent depending on the forage mixture consumed. Release rates of CRD have been found to vary (Berry et al., 2000; Ferreira et al., 2004; Chavez et al., 2011), limiting confidence in their use. Forage intake can also be accurately estimated from a combination of known supplement intake and an estimate of diet composition, which replaces the need for separate alkane dosing to estimate intake (Clark et al., 2004; Elwert and Dove, 2005). If a supplement has or can be labeled with alkanes, the proportion of the supplement in the diet can be determined (Dove and Olivan, 1998). Therefore, if the supplement intake is known, total herbage intake can be determined by proportion (Dove et al., 2002). This would remove the need for CRD. However, supplement might have to be fed daily to decrease errors associated with diurnal and/or daily variations of fecal concentration of markers. A supplement labeled with beeswax is one method that could replace the use of alkane CRD. The inclusion of beeswax-labeled supplements to estimate intake has been shown to estimate intake accurately (Dove and Oliver, 1998; Elwert and Dove, 2005). Disadvantages. A plant wax (odd-chain) alkane is used as an internal digestibility marker and at thesame time the dosed synthetic (even-chain) alkane is used as the fecal-output marker. Since an odd-chain alkane is used as the internal marker, a representative diet sample is required for analysis of its alkane content. Fecal alkanes can be used to determine diet composition in monospecific pastures, which may remove the need to take diet samples. The estimate of the diet composition provides estimates of the alkane concentrations of the whole diet, with which intake can then be estimated. However, under grazing conditions, the diet composition may vary due to selective grazing and/or variation in forage species, which may cause the alkane profiles of individual plants to overlap to the point discernment among the dietary constituents, becomes difficult if not impossible. To date, preliminary work from this Multi-state Research Project has demonstrated that significant variance occurs between laboratories when the same forage sample is subsampled and sent to each lab (Figure 1). In figure 1, Red Clover odd-chained n-alkane (mg/kg) differed between laboratories at Virginia Tech and New Mexico State University. Furthermore, two technicians from each institution conducted n-alkane analysis and obtained poorly repeatable results. This was particularly true in the less experienced lab at New Mexico State University. Likewise, variation between runs from the same technician was unacceptable suggesting that further refinement of the procedure must be pursued. Alkane concentrations of plant species can differ among regions of the United States and thus forages may need to be sampled for analysis from regions that differ in rainfall patterns, annual maximum and minimum temperature, and soil types. The number of alkanes, and the differences in their concentration between the components, limits the number of botanical components that can be distinguished in a mix, whether determined by solving simultaneous equations (Dove, 1992) or by least squares methods (Dove and Moore, 1995). Thus, species with similar alkane compositions may be grouped, and each group considered a botanical component (Bugalho et al., 2002). However, the accuracy of diet composition estimates is likely to decline as the number of dietary components increases (Mayes and Dove, 2000). Furthermore, Lee (2004) and Lee and MacGregor (2004) found that alkanes alone are unlikely to provide good estimates of the composition of the diet when ruminants are grazing complex pastures compared to using microhistology or physical separation. Therefore in complex pastures, rumen cannulated animals are required to obtain a representative sample of consumed forage. Nevertheless, the complexity of range diets and similarity amongst grasses within C3 and C4 classifications may limit the utility of this technique. Further, alkane concentrations may vary considerably across geographical regions and phenology. Cui et al. (2008) and Tanner et al. (2010) reported that herbage alkane concentrations declined with plant maturity. Therefore, it becomes necessary to assess the variation across time in order to account for plant changes with season. To date, this has not been assessed in herbage from the Western United States and across regions with distinct rainfall patterns, climate and soil. According to Mayes and Dove (2000), there are four aspects about the use of alkane markers to estimate diet composition that need to be addressed to evaluate and optimize the technique: 1) more validations of the technique; 2) procedures for statistical analysis of diet composition data to be developed; 3) potential weighting procedures to optimize the discriminatory power of diet composition markers need to be explored and 4) procedures need to be developed that allow marker systems to be used in situations where the number of potential dietary components exceeds the number of available markers. OBJ 1. Assessment of forage n-Alkane profile In order to assess variation both regionally and temporally in the alkane profiles of plants in the Western U.S., unique classes of range forages will be hand plucked by each participating station (AZ, CO, MT, NM, SD, OR, WY, ND, and NE). a. Cool-season grasses (C3): Western Wheatgrass (Agropyron smithii), Cheatgrass (Bromus tectorum) b. Warm-season grasses (C4): Blue grama (Bouteloua gracilis), sideoats grama (Bouteloua curtpendula) c. Legume: Sweet Clover (Melilotus officinalis) d. As many as two additional C3 and C4 grasses and a legume specific to a station Each research station will select a sampling date when forages will be at their peak vegetative and dormant state. This will provide contrast between actively growing plants and those that have senesced in order to assess the variation across maturity. At each sampling, approximately 500 g of dry plant matter will be collected. About 100 g of each sample will be retained as the entire plant. The reaminder will be subdivided into plant parts as appropriate (i.e. leaf, stem, flower, and seed head). These samples will be dried at 55 °C. Samples will then be ground through a 1 mm screen using a mill (Wiley Mill). Samples can then be stored at room temperature until analysis. The alkane concentrations of these samples will be determined using a slight modification of the procedures of Dove and Mayes (2006), which was validated across-labs in the previous period of this project. Initially, the n-alkane concentrations of the entire plants that were sampled at all locations will be determined (i.e., samples a, b and c). As resources allow, and based on the outcomes of modelling mixtures of these plants described subsequently, the n-alkane profiles of additional plants and/or plant parts will be assessed. The utility of combining information from n-alkanes as dietary markers relies on their concentrations being sufficiently distinct among the forage species on offer. Using the measured concentrations of the warm- and cool-season grasses, and the legume, sampled, forage mixtures will be constructed mathematically. In forming those mixtures, potential variability in alkane concentrations will be modeled stochastically, with the degree of variability based on the regional and phenological differences in concentrations observed. The composition of the derived forage mixtures will be predicted using non-negative least squares procedures (Dove and Moore, 1995) and mixing models within a Bayesian framework (Brewer et al., 2005; Philips, 2012). The reliability of prediction will be evaluated. The discriminatory power of the alkanes for discerning the individual forages within the mixtures also will be assessed using multivariate procedures. As an outcome, the efficacy of using alkanes to describe diet selectivity in grazing ruminant animals in complex western rangelands will be more clearly defined. OBJ. 2: Coordinate research and Extension activities in extensive livestock production systems. Members of this Multistate Research Project will coordinate and/or collaborate on common research themes beyond that specific to objective 1. These common themes all contribute to the USDA National Programs NP#101: Food Animal Production, NP#103: Animal Health; as well as NIFA program priority areas of Animal Health and Production, Renewable Energy, Natural Resources, and Environment, which contribute to the challenges as outlined by USDA NIFA, “Keep American agriculture competitive while ending world hunger.” The projects include: Supplementation of grazing ruminants Novel uses of biofuel coproducts, such as distillers grains or algae ( New Mexico, South Dakota) Use of specific nutrients to elicit metabolic or hormonal responses, such as glucogenic precursors (Montana, New Mexico Ruminal fermentation responses to supplementation (New Mexico, Utah) Use of supplementation to elicit fetal programming (Montana, South Dakota, Wyoming) Use of feed additives (New Mexico) Mineral supplementation (Montana) Grazing livestock response in production systems Performance, grazing behavior, and nutrient intake response to range management practices (South Dakota) Livestock performance in mixed crop/livestock systems (Wyoming) Heifer development systems (Montana, New Mexico) Weaning systems (South Dakota, Montana) Comparison of intake in a pen using the Growsafe system with forage intake by cows on range to construct correlation between pen vs. range feed intake and compare relative feed intakes. (Arizona) Extension Methods: Share programming approaches and topics at annual meetings. Poll members of this Multistate Research Project group to solicit topics for Extension programs, such as the Montana Nutrition Conference and Livestock Forum, Range Beef Cow Symposium, youth camps, and field days. Leverage extensive livestock production systems expertise by inviting members of this Multistate Research Project from other states to speak at Extension programs. Encourage members of this Multistate Research Project to track not only the number of individuals reached by Extension programs, but also the number of cows in relation to the total cowherd in the state. Research and Extension efforts and collaborations will be coordinated at annual meetings by providing each station with time to report and discuss research and Extension plans, accomplishments, and publications. Additionally, station reports will be compiled into an annual report of the regional project. These discussions illuminate commonalities that will lead to further collaborations and additional regional research and Extension efforts. OBJ 3: Provide professional development and mentoring opportunities for committee participants, young scientists, and graduate students. Members of the Multistate Research Project will incorporate discussions during each annual meeting led by senior members of the committee over subjects that include but are not limited to grantmanship in the area of grazing livestock research, publishing journal papers, and experimental design. These discussions will be aimed at providing graduate and young scientists advice on how to develop research programs, examples of successful publications and grants, and developing a strong promotion and tenure packet. Members will provide opportunities for other committee members to visit laboratories to develop an open exchange of technologies and lab methodology that will expand capacity and nurture future collaborative efforts.

Measurement of Progress and Results


  • Publish collaborative results demonstrating the effectiveness of procedures developed by this Multistate Research Project. Initially, abstracts and proceeding papers of the research will be presented at relevant regional and national meetings.
  • Research manuscripts will be prepared from the data that is generated from these studies and submitted to recognized scientific journals.
  • A series of Extension fact sheets will be written based on application of information in the journal articles. Segments of the fact sheets or summaries will be placed in Extension newsletters and local newspapers and livestock and forage-related magazines.
  • Web-based information will be prepared with links and information on the project.
  • National, regional and state programs will be held to disseminate findings to stakeholders. For example, this Multistate Research Project is planning to hold the 5th Grazing Livestock Nutrition Conference in July, 2016.

Outcomes or Projected Impacts

  • Determine the efficacy of n-Alkane procedure for determining intake and diet composition of cattle grazing complex mixtures of forages.
  • Promote exchange of ideas, information, and data through sponsoring symposia or workshops on basic understanding of the plant-animal interface and resulting forage-based ruminant management strategies. These professional development activities will promote more rapid advancements in nutritional technologies.


(2014): Work toward standardization of n-alkane procedures across states. Collect plants from participating states. Develop plan for 5th Grazing Livestock Nutrition Conference.

(2015): Summarize and prepare scientific publication on regional and phenological variation of n-Alkane profile of common rangeland plants.

(2016): Host 5th Grazing Livestock Nutrition Conference.

(2017): Identify the strengths and shortcomings of the current Nutrient Requirements of Beef Cattle based on research results obtained from experiments conducted by this Multistate Research Project. Begin planning the 6th Grazing Livestock Nutrition Conference. Begin addressing areas of interest for project renewal.

Projected Participation

View Appendix E: Participation

Outreach Plan

As described previously, this project will have a multi-faceted approach to transfer knowledge, skills, and technologies to stakeholders. This Multistate Research Project will facilitate collaborations, manuscript reviews, and develop new approaches to improve ruminant use of forages in Western rangeland environments. Initial transfer of information to the general public will occur through Extension faculty programming efforts. A series of Extension fact sheets will be written based on the journal articles. Segments of the fact sheets or summaries will be placed in Extension newsletters and local newspapers and livestock and forage-related magazines. Web-based information will be prepared with links to the project. Additionally, development of venues that will disseminate the expertise of members within the group, as well as, nationally and internationally recognized leaders in range livestock production will be a priority for this group. This Multistate Research Project will sponsor symposia or workshops on basic understanding of the plant-animal interface and resulting forage-based ruminant management strategies. For example, the 5th Grazing Livestock Nutrition Conference will be held in July, 2016 in Utah.


The technical committee will organize and function in accordance with the procedures described in "Manual for Cooperative Regional Research." The voting members will elect three officers (Chair, Secretary, and Secretary-elect). These officers plus the immediate past Chair (after the first year) will constitute the executive committee. Specific task subcommittees and coordinators will be appointed as necessary to help coordinate activities among states. The executive committee will conduct any necessary business between annual meetings of the technical committee. The Chair will be responsible for presiding over the annual meeting of the technical committee, preparing the meeting agenda, appointing any necessary subcommittees, and for preparing the annual project report for the year ending with the meeting at which he presides. The Secretary will record and distribute the minutes of the annual meeting. At the end of the annual meeting, the Secretary will become Chair and the Secretary-elect will become Secretary.

Literature Cited

Berry, N., M. R. L. Scheeder, F. Sutter, T. F. Krober, and M. Kreuzer. 2000. The accuracy of intake estimation based on the use of alkane controlled-release capsules and faeces grab sampling in cows. Ann. Zootech. 49:3-13. BIF. 2002. BIF Uniform Guidelines for Beef Improvement Programs. 8th ed.

Brewer, M. J., J. A. N. Filipe, D. A. Elston, L. A. Dawson, R. W. Mayes, C. Soulsby, and S. M. Dunn. 2005. A hierarchical model for compositional data analysis. J. Agric. Biol. Environ. Stat. 10:19-24.

Chavez, S. J., G. B. Huntington, and J. S. Burns. 2011. Use of plant hydrocarbons as markers to estimate voluntary intake and digestibility in beef steers. Livest. Sci. 139:245-251.

Clark, C. E. F., W. J. Fulkerson, K. S. Nandra, and H. Dove. 2004. Estimating pasture intake using n-alkanes and known supplement intake. Anim. Prod. Aust. 25:224.

Cui, J., J. Huang, and S. Xie. 2008. Characteristics of season variations of leaf n-alkanes and n-alkenes in modern higher plants in Qinjian, Hubei Province, China. Chinese Sci. Bullet. 53:2659-2664.

Dove, H. 1992. Using the n-alkane of plant cuticular wax to estimate the species composition of herbage mixtures. Aust. J. Agric. Res. 43:1711-1724.

Dove, H., and A. D. Moore. 1995. Using a least-squares optimization procedure to estimate botanical composition based on the alkanes of plant cuticular wax. Aust. J. Agric. Res. 46:1535-1544.

Dove, H., and R. W. Mayes. 1996. Plant wax components: A new approach to estimating intake and diet composition in herbivores. J. Nutr. 126:13-26.

Dove, H., and R. W. Mayes. 2006. Protocol for the analysis of n-alkanes and other plant-wax compunds and for their use as markers for quantifying the nutrient supply of large mammalian herbivores. Nature Protocols. 1:1680-1697.

Dove, H., M. Freer, and J. Z. Foot. 2000. The nutrition of grazing ewes during pregnancy and lactation: A comparison of alkane-based and chromium/in vitro-based estimates of herbage intake. Aust. J. Agric. Res. 51:765-777.

Dove, H., R. W. Mayes, and M. Freer. 1996. Effects of species, plant part, and plant age on the n-alkane concentrations in the cuticular wax of pasture plants. Aust. J. Agric. Res. 47:1333-1347.

Elwert, C., and H. Dove. 2005. Estimation of roughage intake in sheep using a known daily intake of a labeled supplement. Anim. Sci. 81:47-56.

Ferreira, L. M. M., M. Olivan, M. A. M Rodrigues, K. Osoro, H. Dove, and A. Dias-Da-Silva. 2004. Estimation of feed intake by cattle using controlled-release capsules containing n-alkanes or chromium sesquioxide. J. Agric. Sci. 142:225-234.

Lee, G. J. 2004. Comparison of physical separation and alkane concentrations to estimate the species composition of herbage samples from a pastoral environment. Anim. Prod. Aust. 25:116-119.

Lee, G. J., and C. M. MacGregor. 2004. Comparison of a microhistological analysis of faeces and alkane concentrations of faeces to estimate the botanical composition of the diet of grazing sheep. Anim. Prod. Aust. 25:108-111.

Mayes, R. W., and H. Dove. 2000. Measurement of dietary nutrient intake in free-ranging mammalian herbivores. Nutr. Res. Rev. 13:107-138.

Oliveira, D. E., S. R. Medeiros, L. O. Tedeschi, L. J. Magalhaes-Aroeira, S. C. da Silva. 2007. Estimating forage intake of lactating dual-purpose cows using chromium oxide and n-alkanes as external markers. Sci. Agric. 64:103-110.

Philips, D. L. 2012. Converting isotope valules to diet composition: the use of mixing models. J. Mammal. 93:342-352.

Tanner, A. E., S. R. Blevins, E. Green, R. W. Mayes, and R. M. Lewis. 2010. Characterization of plant cuticular wax markers in native grazing pastures of southwest Virginia. J. Anim. Sci. 88(E-suppl. 2):56 (Abstr.).


Land Grant Participating States/Institutions


Non Land Grant Participating States/Institutions

California Polytechnic State University, San Luis Obispo, USDA-ARS/MT
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