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ARS Home » Pacific West Area » Logan, Utah » Forage and Range Research » Research » Research Project #416563

Research Project: Develop and Evaluate Grass and Legume Mixtures for Improved Livestock Performance

Location: Forage and Range Research

2011 Annual Report

1a. Objectives (from AD-416)
The objectives of this cooperative research project are: 1) Evaluate the relative livestock performance when grazing mixtures of pasture grasses and legumes; and 2) Evaluate the productivity of grass and legume mixtures; and 3) Breed pasture grasses and legumes with enhanced compatibility for use in grazing.

1b. Approach (from AD-416)
This research is an expansion and continuation of the research goals and objectives originally started under SCA #58-5428-4-373 entitled "Develop and evaluate plants for improved livestock performance." The new research will determine livestock performance and pasture productivity of grass-legume mixtures in comparison to commercially fertilized grass monocultures. Standard check cultivars and germplasm from ongoing ARS breeding programs will be established in large and small scale research plots. Large scale plots will be used to compare/determine animal performance, carrying capacity, and nutritional content of grass monocultures versus grass and legume mixtures. Results will be based upon livestock weight gain, forage dry matter production, and in-vitro forage quality analyses. Small plots, using multiple species of grasses and legumes in varying composition ratios, will be established to determine optimum grass-legume mixtures and plant densities that maximize pasture productivity in comparison to commercial fertilizer. Livestock grazing on these plots will ensure realistic pressures common to pastures. The role that endophyte infection of grasses has on grass-legume mixture compatibility may be evaluated. Livestock and plant data will be utilized in plant improvement programs to breed for improved compatibility among pasture grasses and legumes.

3. Progress Report
The objective of this project was to determine the livestock performance and pasture productivity of grass-legume mixtures in comparison to fertilized and unfertilized grass monocultures. The project has three components including evaluating livestock performance, determining pasture productivity, and developing grasses and legumes with enhanced compatibility. During FY-2011: The work outlined in the Statement of Work (SOW) was initiated. It was discovered that legumes had died out of previously established pastures. These tall fescue-legume (alfalfa and birdsfoot trefoil) pastures were re-established in 2011. However, existing pastures were utilized to collect a second year’s data on livestock intake and gains, fatty acid profiles, ruminal pH and ammonia, and forage production and quality comparing tall fescue with and without N-fertilizer and feedlot treatments. Preliminary results were presented at the Annual Meeting of Western Section, American Society of Animal Science in June 2011, and at the Joint Annual Meeting of ADSA-ASAS in July 2011, and indicated that applying N fertilizer to tall fescue did not influence growth performance or carcass characteristics. Additional research initiated during FY2011 included installation of lysimeters during the re-establishment of the tall fescue-legume pastures, which were used to determine the initial nitrogen in the leachate. These pastures will be grazed next year. Small plots of binary mixtures of five grasses (orchardgrass, tall fescue, meadow brome, timothy, and perennial ryegrass) and three legumes (alfalfa, birdsfoot trefoil, and cicer milkvetch) were established and data collection was begun. Ratios in the mixtures included 0, 25, 50, and 75% legume composition. Samples from these plots were used to initiate development of an NIRS equation that can determine composition of legume in mixture plots. In breeding work, two studies were initiated to determine phenotypic and genetic compatibility of tall fescue and orchardgrass with alfalfa. In addition, alfalfa breeding lines were evaluated to determine the physiological and genetic controls of salt tolerance by quantifying the amount of salt-related elements accumulated in shoots and leaves when irrigated with saline water. Monitoring Methods: The ADODR monitored this research via email, phone calls, personal meetings with the cooperator, and site visits to the field.

4. Accomplishments