With its solid reputation for providing a reliable source of livestock fodder throughout the year, grass silage is the cornerstone of many rations, but how successful it is for animal health and performance at the feeding stage is dictated by many variables. 

To get it right, there are several key points farmers need to consider in that journey from field to feeding out.  

There are multiple reasons why some grass crops do not produce good silage, including harvesting in wet conditions which complicates the acidification process. Get it wrong at the fermentation stage and there can be clostridial fermentations, protein degradation, large dry matter (DM) losses and the production of biogenic amines. 

These factors all put animal health and farm productivity at risk. 

With all these challenges in mind it is clear why the skill of making silage is often a delicate balance between many factors. It’s not just about preserving fodder; it’s about ensuring the biological processes work to maintain the nutritional value and cleanliness of the silage. 

It all begins in the field, explains Lientjie, Colahan, Technical support manager for Lallemand Animal Nutrition UK, she describes wet silage as a “haven for undesirable microorganisms’’. If uncontrolled, these bad bacteria can result in significant DM and nutrient losses, excessive spoilage, even adverse health effects for livestock.  

“We often overlook the importance of the initial stages,’’ adds Lientjie  “Clean forage is the first step towards quality silage.” 


There are simple and cost-effective steps that every farmer can take to ensure they produce clean and superior quality silage.

1 – Manure management

Manure and slurry contain valuable fertilising nutrients for growing grass, but they can harbor pathogens such as E. coli and Clostridia.  

To minimize the risk of contamination, a 28–32-day interval is recommended between when manure or slurry is applied, and grass is harvested.

2 – Timing of harvesting

Harvesting grass at the wrong point of its growth cycle or when conditions are wet can increase populations of harmful bacteria in the silage, compromising its quality. 

It is therefore essential to ensure that the correct maturity levels and moisture content are achieved. 

3 – Cutting height

Setting the mower at a low height risks soil contamination and this will have a detrimental impact on fermentation in the clamp. 

When conditions are wetter than ideal, raise the mower height to reduce that danger of contamination and the consequential risk of introducing Clostridia into the feed.

4 – Ensiling 

Good management practices at the ensiling stage really pay off. The goal is to promote lactic acid bacteria (LAB) growth.  

Proper preparation (including cleaning to remove residual spoilage microbes), packing, and sealing are all necessary to create an environment where LAB can thrive.  

5 – The role of an inoculant such as MAGNIVA

MAGNIVA plays a pivotal role in ensuring the dominance of LAB during fermentation, quickly lowering pH levels to inhibit bad bacteria.  

Selecting the right inoculant is a science in itself, says Lientjie.  “It’s about making sure the correct inoculant is used for the conditions encountered.” 

“In the case of wetter silage for example, especially those that are below 30% DM, a higher concentration homofermentative bacteria inoculant, such as MAGNIVA Classic or Classic +, is recommended.’’   

To compensate for potentially low sugar levels, inoculants that contain enzymes are also advised. 

Recommendations for ensiling: 

  • Cleanliness: keep silage structures and equipment free of mud and soil to prevent contamination 
  • Packing density: correct packing removes air, a process that is especially critical for wetter silage.
  • Sealing: a plastic oxygen barrier is vital to prevent air ingress and the growth of molds and yeast.


Key Messages 

Wetter grass silage must be carefully managed to ensure it produces the best quality feed and to minimize losses.   

Poor quality grass silage with high spoilage levels can lead to rumen disruption and significant production losses.  

By following expert recommendations and utilizing quality inoculants, farmers can produce clean, nutritious silage that supports animal welfare and maximizes farm profitability.