Week 4

Roughages

High moisture forages – Silage

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• High-moisture forage
• 60% to greater than 70% moisture
• Controlled fermentation of high-moisture forages
• Harvested at stages of forage growth and fed as necessary
• Given appropriate management
• Palatable
• High nutritional value
• Primarily fed to beef and dairy cattle
• Figures 9.11 and 9.12 – Consuming rations containing silage





• Fed to sheep and horses
• Favorable production results
• Maximize DMI, ensile at minimum moisture required for ensiling
• Ensiled
• Grass and legume forages
• Corn and sorghum grain crops
• Various crop surpluses and residues
• Effective method to maximize yield of digestible nutrients per unit of land
• Ensiling
• Process
• High-moisture forages harvested
• Loaded into structure
• Anaerobic fermentation preserves nutrients
• Factors
• Physical and chemical properties of forage
• Establishment and maintenance of anaerobic environment
• Composition and activity of population of microorganisms
• Approximately 2-3 weeks
• Phase one
• Aerobic
• Immediately after harvest
• Plant enzymes and aerobic microorganisms
• Convert organic materials to carbon dioxide, water, and heat
• Nonstructural CHO and proteins
• Extended duration
• Excessive nutrient loss and heating
• Completed with establishment of anaerobic conditions
• Less than six hours
• Phase two
• Initial anaerobic fermentation
• Acetic acid producing microorganisms
• Nonstructural CHO to acetic acid
• Acetic acid
• Energy source
• Reduce pH to app. 5.0
• One to three days
• Phase three
• Lactic acid producing microorganisms
• Nonstructural CHO to lactic acid
• Lactic acid
• Most desirable acid
• Strong acid
• Energy source
• Palatable
• Completed when pH is 4.0-4.5
• Inhibiting microbial growth
• Preserving nutrients in forage
• Indicators
• pH
• Grass: 4.5
• Corn silage: 4.0
• Composition of acids
• Lactic acid predominate
• 4-8% of DM
• Phase four
• Feed-out
• Period in which unloaded from structure and fed
• Exposed to oxygen
• Oxygen initiates secondary aerobic degradation and yeast and fungi growth
• Minimize duration of time from exposure to oxygen to animal consumption
• Harvesting
• Figure 9.13 – Corn silage being cut, chopped, and transferred to forage wagon in field



• Stage of maturity
• To maximize yield of digestible nutrients per unit of land
• Table 7-20 on page 147 of text – Harvest maturity for various forages
• Moisture content
• Efficiency of microbial fermentation, establishment of anaerobic conditions, and minimizes seepage
• Varies by silo and forage
• Table 7-21 on page 148 – Methods to estimate moisture content of forage
• Table 7-20 on page 147 – Acceptable range of moisture at ensiling for various forages
• Figure 9.14 – Associated losses at various moisture levels with various ensiling structures



• Classifications
• Direct-cut; 70% or greater moisture
• Corn and other grain crops
• Wilted; 60-70% moisture
• Grasses and legumes
• Figure 9.15 – Wilted forage collected, chopped, and transferred to wagon in field



• Low-moisture; 40-60% moisture
• Grasses and legumes
• Nonstructural CHO content
• Efficiency of ensiling process
• Primary substrate for acid production
• Optimal maturity promotes adequate levels
• Chopping
• Promotes establishment of anaerobic conditions
• In general, optimal is 1/4” to 1/2”
• Type of forage, ensiling structure, and rate of inclusion in ration
• Table 7-20 on page 147 – Recommended length of cut or chop for various forages
• Loading and packing
• Loading
• Establish and maintain anaerobic conditions
• Unloading
• Rapidly, continuously, consistently
• Packing
• Establish and maintain anaerobic conditions
• Consistently and sealed rapidly
• Method dependent on ensiling structure
• Ensiling structure
• Vertical, conventional silos (tower silos)
• Figure 9.16 - Vertical, conventional silo (right)



• Vertical, oxygen-limiting silos
• Figure 9.16 – Vertical, oxygen-limiting silo (left)



• Oxygen-limiting store high-moisture grains and low-moisture forages
• Horizontal, bunker silos
• Figure 9.17 – Horizontal, bunker silo



• Bag silos
• Figure 9.18 -  Silage being bagged



• Requirements
• Establishment and maintenance of anaerobic environment
• Efficient loading, packing, and unloading
• Sizing
• Factors
• Loading, packing, and unloading of silage
• Quantity of forage fed per day
• Duration of time forage fed
• Vertical
• Minimize feed losses
• Loading and unloading efficient
• High investment in facility and equipment
• Horizontal
• Low capital investment in facilities and equipment
• Loading and unloading labor-intensive
• Potential for high feed losses
• Bags
• Low capital investment
• Minimal feed losses
• Loading and unloading labor-intensive
• Losses
• Minimize to maximize yield of digestible nutrients
• Average losses are 15-25% of DM
• Associated with harvesting and handling minimal
• Primary losses associated with fermentation, storage, and feed-out
• Table 7-22 on page 149 – Summary of harvesting methods for alfalfa with associated losses
• Additives
• Improve the ensiling process and nutritional value of ensiled forage
• Not required
• Not substitute for management
• Classified
• Nutrients
• NPN and other protein sources
• Feeds low in CP and high in energy
• Increase CP
• Fermentable CHO sources
• Grains and molasses
• Feeds low in energy and high in CP
• Efficiency of ensiling process
• Chemical preservatives
• Organic acids
• Reduce degradation of CP and CHO
• Especially, direct-cut
• Inhibit select microorganism
• Biological agents
• Lactic acid producing microorganisms
• Establishment of and fermentation by lactic acid producers
• Microbial enzymes
• Increase quantity of nutrients available for fermentation
• Evaluation of nutritional value
• Sensory
• Visual, tactile, and olfactory senses
• Bright, crisp color, firm texture, clean acidic odor, and absent from antinutritional factors and contaminants
• Analytical
• Standard forage analyses
• pH
• Composition of acids
• Nitrogen component
• Corn silage
• In U.S., most popular ensiled forage
• Figure 9.19 – Field of corn silage



• Figure 9.20 – Corn silage being harvested



• Favorable characteristics associated with crop production, nutritional value, and feeding value
• Crop production
• High yield of digestible nutrients per unit of land
• Nutritional value
• Structural CHO and nonstructural CHO (e.g. energy)
• High to moderate in DE
• TDN
• 65-75% of DM
• Low to moderate in CP
• 8-9%
• Average NDF
• 51%
• Average ADF
• 28%
• Feeding value
• Palatable
• Supplement with protein, mineral, vitamin, and potentially, energy to maximize nutritional value
• Factors
• Hybrid selection
• Fertilization
• Maturity at harvest
• Yield and digestibility of nutrients and ensiling characteristics
• Identified by location of milk line
• Milk line
• Line in kernel separating liquid and solid portions of kernel
• Figure 9.21 – Various milk lines



• Figure 7.16 on page 155 of text – Kernel milk line (e.g. maturity) and expected DM yields
• As plant matures, outside to inside
• Table 7-33 – Plant composition and energy yields of whole plant corn harvested at three different maturities
• Optimal stage to maximize energy value of silage, moisture content for ensiling, and maximize animal consumption is one-half to two-thirds down kernel
• Moisture level 65-70%
• Harvest, storage, and feeding management
• Chop size
• Table 7-20 on page 147 – Optimal chop size for corn silage
• Processing
• Improve nutritional value
• Disrupt physical structures and reduce physical size of particles of plant
• Additional ensiled forages
  • Sorghum, grasses, legumes, small grains, and crop residues and surpluses
  • Nutritional value and various silage production specifics will differ, basic principles of silage production also apply
• Ensiling also means to manage specific forage issues
  • Ensiling will reduce nitrate, prussic acid, and various other compounds, and reduce opportunity for bloat