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Crop Science Abstract - SYMPOSIA

Advancement in Assessment and the Reassessment of the Nutritive Value of Forages


This article in CS

  1. Vol. 51 No. 2, p. 390-402
    Received: June 9, 2010

    * Corresponding author(s): Joe.Burns@ars.usda.gov
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  1. J. C. Burns *
  1. USDA-ARS and Dep. Crop Science and Dep. Animal Science, North Carolina State Univ., Raleigh, NC 27695


Forages, primary producers of carbon compounds, provide energy and nutrients when consumed by herbivores, resulting in “value-added” animal products as meat, milk, and fiber and, in some cases, recreation. How a forage supports value-added products of interest has been a concern since the mid 1800s. The characteristic of a forage that composes its nutritive value (NVAL) and its consumption and conversion by the animal determines the quality of the nutrient entity and provides an estimate of its forage quality. The first system to address forage NVAL emerged in the mid 1880s and was termed the Weende proximate analysis. Forages were separated into crude protein (CP), crude fiber (CF), ether extract (EE), nitrogen-free extract (NFE), ash, and water. The concept of nutrient entity followed in the 1950s. By the mid 1960s, the neutral detergent fiber (NDF) system partially replaced proximate analysis and the two, along with innovations in solubility, serve as methodologies for estimating NVAL. An assessment of NVAL from the microbial view point was introduced in the early 1960s by the two-stage in vitro dry matter disappearance (IVDMD) method, followed in the 1970s by continuous cultures. Innovation in spectral technology introduced near infrared spectrophotometry in the mid 1980s providing a rapid analysis of the NVAL fractions. A reassessment of the approach to estimating forage quality, based on the microflora's view of “particle value,” using near infrared spectral scans of the “as fed” forage has been proposed.

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