An Introduction to Silage: Principles and Best Practices
Silage is forage preserved through acidification via fermentation in the absence of oxygen. Any green crop with adequate water-soluble carbohydrates (WSCs) and proper moisture content can be ensiled. Common crops include corn, cereals, alfalfa, faba beans, perennial grasses, and even some weeds like kochia. In Manitoba, the most popular silage crops are corn, cereal grains, and alfalfa.
 
 
The Ensiling Process
  1. Harvest: Cut and chop the crop at the correct stage and moisture level.
  2. Storage: Place in a silo, pack tightly, and seal quickly to exclude air.
  3. Fermentation:
    • Initial aerobic phase consumes oxygen, producing heat and nutrient loss.
    • Anaerobic fermentation follows, producing lactic acid and lowering pH.
    • Stabilization occurs within 3–4 weeks, making silage ready for feeding.
 
Advantages of Silage
  • Can be harvested in almost any weather.
  • Lower dry matter losses compared to hay.
  • Allows use of diverse crops and salvages damaged crops.
  • Provides large quantities of uniform feed.
  • Mechanized handling from field to feed trough.
Disadvantages
  • Requires more labor and time than hay.
  • Odor may be objectionable near populated areas.
  • High capital cost for storage and equipment.
  • Limited market potential; transport is costly and inefficient.
 
Types of Silos
  • Round bale silage
  • Horizontal (bunker) silos
  • Vertical silos (concrete stave, oxygen-limiting)
 
Factors for High-Quality Silage
  • Rapid Filling and Sealing: Prevents spoilage and nutrient loss.
  • Moisture:
    • Ideal: ~65% for most silos; 50–60% for round bale silage.
    • Too wet: Poor fermentation, seepage, freezing risk.
    • Too dry: Poor packing, increased spoilage, leaf loss.
  • Harvest Stage:
    • Cereals: Early dough stage
    • Corn: Hard dough stage
    • Legumes:
      • Alfalfa - Early to full bloom
      • Peas, Beans, Lentils and Fababeans – when pods begin to wrinkle
  • Particle Size: Chop to ¼–½ inch for better packing and fermentation.
  • WSC Content: Higher sugars improve fermentation; cereals > legumes.
  • Buffering Capacity: Legumes resist pH drop, requiring careful management.
 
Key Takeaways
  • Harvest at correct stage and moisture.
  • Fill, pack, and seal silos quickly.
  • Use proper chop length and consider inoculants for challenging crops.
  • Monitor fermentation and feed quality before use.