Feed additives lift rumen health

With dairy cows yielding more milk and consuming more feed to provide the nutrients to produce more, cows have to cope with higher levels of acids in the rumen.  The replacement of grain with good quality roughage can alleviate the buildup of these acids, however, at a certain point of replacing roughage with grain, energy intake becomes limited and will start to influence production.

Sub-acute ruminal acidosis needs to be considered in many of our high producing herds due to the conditions described above. Ruminal acidosis effects fibre digestion and ruminal function.  It reduces fertility, can lead to laminitis and increased somatic cell counts, and affects herd health and productivity. 

Rumen pH fluctuates throughout the day from a normal pH of 6 down to an acidic range of about 5.5. Where the rumen pH remains at the acidic levels for prolonged periods of time, sub-clinical acidosis sets in. This is due to the reduced growth and activity of fibre digesting microbes and the proliferation of lactic acid producing microbes. Lactic acid production in the rumen is undesirable because it is not as well absorbed as the other acids, which leads to its build up.

Feed additives can help greatly in the prevention of ruminal acidosis and help to maintain a healthy rumen. Buffers are regularly fed, such as sodium bicarbonate and magnesium oxide. Most buffers on the market have a mode of action that alkalises the acids in the rumen and the better ones buffer excess acid over an extended period of time which matches acid production and the rumen outflow rates.

Another school of thought is tackling rumen health and feed efficiency at the heart of rumen function. 

Feeding specific rumen yeast cultures helps maintain a healthy rumen environment and improved fibre degradation. These live yeast cultures stabilise the rumen pH by reducing the number of lactic acid producing bacteria and increases the number of lactic acid utilising bacteria in the rumen. 

Bach et al, in research published in 2007, showed LevucellSC, a rumen specific live yeast, improves the stability of the rumen pH which also led to the cows eating more regularly. Improved fibre degradation is due to indirect and direct effects in the rumen even when acidosis is not an issue. Oxygen uptake by yeasts is also an important impact due to the fact that for the optimal fermentation of fiber, anaerobic conditions are required. 

Ondarza et al, in 2010 published a multiple study analysis of LevucellSC showing how the live yeast improved milk production and increased feed efficiency significantly over the control groups, due to the effects on rumen health and improved fibre degradation.

Over the last two decades feeding yeast cultures have gained considerable scientific interest. Effects of a yeast preparation are strain dependant, so not all preparations are equivalent in efficiency. Strain guaranteed products with guaranteed concentration and consistent efficacy are important criteria when selecting the right yeast culture. 

• Paul Drew is a nutritionist with Vitec Nutrition. References are available from the author.