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Article| Volume 74, ISSUE 10, P3630-3644, October 1991

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Balancing Carbohydrates and Proteins for Optimum Rumen Microbial Yield1

  • W.H. Hoover
    Affiliations
    Division of Animal and Veterinary Sciences, West Virginia University, Morgantown 26506
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  • Author Footnotes
    2 Department of Animal Science, Food and Nutrition, Southern Illinois University, Carbondale.
    S.R. Stokes
    Footnotes
    2 Department of Animal Science, Food and Nutrition, Southern Illinois University, Carbondale.
    Affiliations
    Division of Animal and Veterinary Sciences, West Virginia University, Morgantown 26506
    Search for articles by this author
  • Author Footnotes
    1 Published with the approval of the director of the West Virginia Agriculture and Forestry Experiment Station as Scientific Article Number 2242.
    2 Department of Animal Science, Food and Nutrition, Southern Illinois University, Carbondale.
Open ArchiveDOI:https://doi.org/10.3168/jds.S0022-0302(91)78553-6
Balancing Carbohydrates and Proteins for Optimum Rumen Microbial Yield1
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      Abstract

      Establishing conditions under which rumen fermentation will be optimized requires an understanding of the nutrient requirements of the mixed microbial population. The major nutrients required by rumen microbes are carbohydrates and proteins, but the most suitable sources and quantities needed to support maximum growth have not been determined. Digestion of proteins results in the production of peptides, which can accumulate in the rumen. Peptides are further hydrolyzed to amino acids, some of which are deaminated, producing ammonia. Although peptides, amino acids, and ammonia all may individually serve as sources of N for various microbes, the total population achieves the highest growth rate on mixtures of all three sources. In a somewhat analogous manner, carbohydrates are digested by exoenzymes to oligosaccharides that are available for crossfeeding by the mixed microbial population. Based on data from both in vitro and in vivo studies, there is general agreement that rate of digestion of carbohydrates is the major factor controlling the energy available for microbial growth; in addition, rate of digestion of total carbohydrate is directly related to proportion of starches, pectins, and sugars. Proteins affect both total fermentation and production of microbial DM per unit of carbohydrate fermented. It appears that the quantity of ruminally available protein needed to optimize microbial growth may, under some conditions, be as high as 14 to 15% of diet DM.

      Key words

      Abbreviations key:

      CC (continuous culture), DIP (degradable intake protein), NSC (non-structural carbohydrates), YATP (efficiency of microbial DM production)

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      Article info

      Publication history

      Accepted: January 14, 1991
      Received: August 31, 1990

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      DOI: https://doi.org/10.3168/jds.S0022-0302(91)78553-6

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      © 1991 American Dairy Science Association. Published by Elsevier Inc.

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