Corn silage (also known as maize silage) is a forage feed made from whole corn (maize) plants harvested at the optimal maturity stage and preserved through ensiling. The ensiling process preserves forage through controlled fermentation, making silage a fermented feed. It is widely used as a basic forage in dairy and beef cattle nutrition due to its high starch content, digestible fiber, and excellent palatability.
Proper silage management increases nutritional value, digestibility, and long-term storage quality, which in turn will positively impact health and productivity. However, poorly managed silage can lead to nutrient losses, mold growth, and mycotoxin contamination, negatively affecting herd health. In the next paragraphs, we explore key practices for optimizing corn/maize silage.
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Importance of high-quality corn/maize silage
Corn silage is a primary source of energy for dairy cows, providing a combination of digestible fiber and fermentable carbohydrates, primarily starch, which serves as essential precursors for microbial fermentation and volatile fatty acid (VFA) production in the rumen.
Research has shown that well-preserved corn silage can increase milk yield by 5-10% compared to lower-quality silage (Kung & Muck, 2017). These results are related to the fact that good quality silage promotes enhanced rumen health and microbial efficiency (Kung & Muck, 2017) and can lead to reduced incidences of metabolic disorders such as acidosis and ketosis (Singh et al., 2021)
On the other hand, poor-quality silage can have detrimental effects on health, leading to a range of metabolic, digestive, and immune-related disorders. One of the most significant issues is mycotoxin contamination, which results from mold growth in improperly stored or fermented silage. Also, aerobic spoilage caused by excessive oxygen exposure allows yeast and mold growth, leading to heating of silage, nutrient degradation, and reduced palatability (Borreani et al., 2018).
Proper silage management is essential to maintain a healthy, high-performing dairy herd.
Tips for optimizing corn/maize silage
Harvest Timing and Maturity Stage
Starting at the very beginning, optimal harvest time is essential. The ideal time to harvest corn silage is 28-38% dry matter (DM). There is a simple test that can be used in the field called the 'milk line test'. The milk line is where the solid and liquid part of the grain meet. Looking at one grain, when the line is about halfway down, the crop is ready to harvest.
Harvesting too early results in excess moisture, leading to poor or uncontrolled fermentation, while late harvesting (>40% DM) causes fiber lignification, reducing digestibility (Bolsen, 2018).
Silage and grain Processing
The whole plant (stalk, leaves, cobs, and grains) is chopped into small particles (8-15 mm). The chopped maize is compressed and packed tightly in silos, bunkers, or silage bags to remove oxygen. This creates an anaerobic (oxygen-free) environment that is essential for proper fermentation. Properly processed grains break the pericarp, allowing better microbial access during ruminal fermentation. Good silage processing should imply a >90% grain breakdown in processed silage.
Silage packing and ensiling
Proper packing and ensiling create the anaerobic conditions essential for controlled beneficial lactic acid bacteria (LAB) which convert plant sugars into lactic acid, lowering the pH to ~3.8-4.5. The low pH preserves the silage, inhibiting spoilage organisms like molds and yeasts. Preventing oxygen infiltration is crucial to ensure a controlled anaerobic fermentation process for conserving the forage. Using thin layers of forage and packing it with heavy equipment is a good practice. Also sealing the silo timely with oxygen barrier material to minimize aerobic spoilage (Borreani et al., 2018).
Use of silage inoculants
The use of silage inoculants improves fermentation efficiency by accelerating lactic acid production, reducing dry matter losses, and enhancing aerobic stability. These can be used but they are not a must.
Types of Inoculants:
- Homofermentative LAB (Lactobacillus plantarum, Pediococcus spp.) – Improves lactic acid fermentation.
- Heterofermentative LAB (Lactobacillus buchneri) – Reduces spoilage by inhibiting yeasts and molds.
Mycotoxins and mold contamination
Mycotoxin contamination in silage, especially by Fusarium spp., poses serious health risks, including immunosuppression and reduced feed intake. To avoid this, prevention strategies should be put in place: harvest at the correct moisture level (28-38% DM), store silage under anaerobic conditions to limit mold growth, use mycotoxin binders in TMR when necessary or preventively.
Silage feeding and aerobic stability
After 30-60 days of fermentation (depending on the size of the silo), the silage is ready for feeding. It should be removed from the silo or bunker in thin layers to prevent aerobic degradation. Once silage is exposed to air, yeast and mold growth can rapidly degrade feed quality.
Take Home Messages
Benefits of Maize Silage in Dairy Production
- High energy feed: Supports high milk yield and weight gain in cattle.
- Good digestibility: Provides fermentable carbohydrates for rumen microbes.
- Cost-effective: Reduces dependence on expensive grains or concentrate feed
- Long-term storage: Proper ensiling preserves nutrients for months.
- Flexible feeding: Can be fed alone or blended in TMR with hay, grains, and protein supplements.
Challenges of Maize Silage
- Risk of mycotoxins: Poor storage conditions can promote mold growth and Fusarium toxin contamination.
- Fermentation losses: If oxygen enters the silo or if fermentation is not properly controlled, spoilage bacteria can degrade nutrients.
To maximize its nutritional and economic benefits, corn silage must be harvested, stored, and managed properly to prevent spoilage and mycotoxin contamination.
References
Borreani, G., Tabacco, E., Schmidt, R. J., Holmes, B. J., & Muck, R. E. (2018). Silage review: Factors affecting dry matter and quality losses in silages. Journal of Dairy Science, 101(5), 3952-3979. https://www.sciencedirect.com/science/article/pii/S0022030218303205
Bolsen, K. K. (2018). Silage review: Safety considerations during silage making and feeding. Journal of Dairy Science, 101(5), 3981-3994. https://www.sciencedirect.com/science/article/pii/S0022030218303308
Kung Jr., L., & Muck, R. E. (2017). Silage harvesting and storage. Large Dairy Herd Management. https://www.researchgate.net/publication/324223688_Silage_Harvest_and_Storage
Singh, J., Nimbalkar, V., & Verma, H. K. (2021). Dairy farming innovations for productivity enhancement. IntechOpen. https://www.intechopen.com/chapters/79567
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