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Dec 10, 2019

Ruminant Microbiota Insight: Part 3 – The key to performance

Dec 10, 2019

Ruminants depend on microbial fermentation within the rumen to acquire energy from plant material. The different fractions from plant cell walls are not entirely physically accessible and achieve various degrees of digestibility in the rumen.

To improve animal productivity, a portion of the forage diet is often substituted with readily fermentable carbohydrates. However, the supplementation of diets with readily fermentable carbohydrates is known to depress rumen fiber degradation. Additionally, the major fiber-degrading bacterial species — Fibrobacter succinogenes, Ruminococcus albus, and R. flavefaciens as well as rumen fibrolytic fungi — are particularly vulnerable to a rumen pH at 5.8 or lower.

How rumen pH affects the fibrolytic microflora
How rumen pH affects the fibrolytic microflora

The challenge for ruminant nutritionists is to provide a balanced nutrient intake, maximize digestion and, ultimately, improve the efficiency of this process to convert to feedstuffs into milk, meat or wool.

Indicators and risk parameters of poor fiber degradation include:

  • Decreased animal performance. Low milk production, milk fat and a reduced-fat to protein ratio may be due to impaired rumen fermentation in lactating dairy cattle.
  • Liquid manure and presence of undigested grain. Undigested processed grains in the feces because of poor rumen efficiency may be due to an increased passage rate due to an imbalanced or low diet digestibility.
  • Lower body condition.
  • Heat stress (high temperature and/or humidity) also increases the risks of acidosis and low fiber degradation.


For more information on rumen fermentation, visit: