Biochemistry of Silage Production

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Advanced Animal Nutrition (LPGS 514)
Biochemistry of Silage Production
Presenter Tekleab Serekebrhan Mekele University
August 2006
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1. Introduction
Silage

• Silage It is a biochemical process product of
  both the plant and microbial activities and
  their effect on the plant material by achieving
  anaerobic condition.
• Moist feed made by the transformation of plant
  materials to a preserved fodder through anaerobic
  condition
• It has been used since 18th century in Sweden

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Introduction Conti.

• Advantage
• Intensification of forage production
• Less risk associated with weather conditions
• reduced loss of leaves and other small plant
  parts of high quality in the field
• Disadvantage
• requires high capital investment
• no off farm market opportunity

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Introduction Conti.
Objective

• - To show who the biochemistry of silage
  production takes place.

Method

• - referring books, Literatures, internet,
  personal experience

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Discussion

• The biochemistry of Silage production involves
  any activities or reactions which takes place and
  results alteration in the chemical and physical
  status of the ensiled plant material
• The two main components in the biochemical
  process of silage production
• 1.The plant species and stages of harvest
• 2.The chemical change or reactions resulting from
  the activities of plant enzyme and microbes
• (Core of paper)

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Discussion Cont.

• Plant enzymes
• These acts on plant tissue just after cutting and
  during the earlier stage in silo undergoes
• Respiration (oxidative degradation of organic
  compound to yield energy) glycolysis, oxidation
  (TCA)
• sugar oxygen ? carbon dioxide water heat
• Proteolysis Once the material ensiled degrade
  protein to peptides and amino acids and decline
  as the pH falls.

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Discussion cont.

• Microorganisms
• fresh herbage - Aerobic fungi and bacteria
• --- as anaerobic condition develop in the silo
  they are replaced by anaerobic bacteria, able to
  grow in the absence of oxygen (Mc Donald et al,
  1995)
• Fermentation

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Discussion cont. Fermentation Processes

• Silage fermentation is a biological process
  whereby bacteria are responsible to convert WSC
  to organic acids including LA, AA, ethanol,
  mannitol and CO2.

• Phases are classified based on
• the microbes involved in the process
• 4 phases 2undisirable
• absence or presence of oxygen in the chemical
  process.
• 2 phases

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based on the type of microbe involved
the Process

• Phase 1-Respiration
• C6H12O6 6 O2 ------gt 6 CO2 6 H2O 3.8
  Mcal/kg sugar
• oxygen is reduced and NADH2 is oxidized
• Phase 2 Early fermentation (enterobacteria)
• water soluble ---? into acetate, ethanol,
  hydrogen and CO2.
• Deaminate amino acids which result in decrease
  palatability.
• Phase 3 Lactic acid fermentation
  (homofermentatives LAB pyruvate (Glycolysis)
  ?LA
• organic compound is reduced and NADH2 is oxidized
  
• free sugars ? lactic acid lowering pH
• Phase 4 Stabilization phase (LAB)
• low pH created in phase 3 stops plant enzymatic
  activity and further microbial metabolism
  degradation

chemical pathway of lactic acid (diagram)
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the Process
respiration
fermentation
Deterioration
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the processUndesirable phases
Two other undesirable phases can also take place
and cause important loss of dry matter and forage
quality in a silo

• 1. Butyric acid fermentation by clostridia (BAB)
• ( if phase 3 (LAF) is fail to achieve low pH in
  phase 4)
• 2) Aerobic deterioration caused by molds and
  yeast- just after O2 exposure

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Other factors

• Plant maturity and moisture content
• optimum 50-65 moisture before it is put in silo
• If low moisture - restricted fermentations,
  thereby producing less stable silages that have
  lower lactic acid concentrations and are less
  acidic
• If high moisture - effluent
• - clostridial fermentations
• Proper maturity ? adequate fermentable sugars for
  silage bacteria and maximum nutritional value for
  livestock

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Other factors cont.

• Nature of the plant
• Legumes they have high protein content.
• Problems
• low content of sugars,
• high buffering capacity (resist pH changes)
• high moisture content.
• Recommended type
• Carbohydrate rich crops that contain more than
  two part of carbohydrate to one part of protein.

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Other factors cont.

• Silage additives
• Promote high levels of lactic acid production and
  create a low pH (3.8-4.2).
• (1) inoculants ensure adequate quantities of
  lactic acid-producing bacteria (mostly bacteria)
• (2) enzymes (release additional sugar fiber
  deg.)
• (3) substrate sources primarily sugars, such as
  molasses, glucose, sucrose and dextrose
• 4) inhibitors inhibiting the fermentation
  process and growth of all microbes in the silo
  (formic acid)

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Fermentation guide smell and texture (Physical
Assessment)

• Good Yellow or brown-green ,Sweet acid
  smell, Firm texture  
• Overheated Dark, brown-black Burnt caramel-
  tobacco smell, Dry, disintegrated texture  
• Butyric Olive green, Evil putrid smell ,Soft and
  slimy
• Moldy Dark brown with white mould, Musty smell
  Dry, easily broken texture
• Putrid/rotted Green/ black, Putrid smell, Wet,
  slimy  

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Conclusion

• Chemical changes are the result of plant enzymes
  activity (respiration and proteolysis) and action
  of microbes depending on the absence or presence
  of oxygen.
• The quality of silage is more dependant on the
  quality of plant material they used
• Factors necessary for good fermentation of
  silage
• anaerobic conditions (no O2 air)
• proper moisture
• sufficient plant water-soluble carbohydrates or
  sugars
• proper bacteria

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Tip
Dairy cattle feed on silage, www.oznet.ksu.edu/pr_
silage A Trouble-\ Shooter For Common Silage
Problems
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Thank you