Fiber Length for Corn Silage Neil Broadwater Regional Extension Education Livestock

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Fiber Length for Corn SilageNeil
BroadwaterRegional Extension Education --
Livestock
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The Feed Pyramid

• Dairy Rations begin with high quality forages
• Pyramid by Rick Lundquist, 1995

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Role of Fiber for the Dairy Cow

• Fiber length affects forage quality, compaction
  for proper fermentation and roughage value for
  proper rumen function.
• Incorrect fiber length can lead to cows going off
  feed, low fat test, decline in milk production,
  DAs, laminitis, and liver abscesses.
• Effective fiber -- needed to form a fiber mat
  that is responsible for the stimulation of cud
  chewing, salivation and rumen motility.
• She needs to spend 35-40 of her time chewing her
  cud to produce adequate amounts of sodium
  bicarbonate and stimulate rumen digestion.
• Cows will consume 11 to 13 meals per day, about
  20 min in length.
• Thats why feeding or pushing feed up to the cows
  several times/day is an important practice.

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Particle Size Affects Rumination

• If too fine
• chewing ?, saliva ?, buffering capacity ?, pH ?
• If adequate
• chewing ?, saliva ?, buffering capacity ?, pH ?

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Assessing Fiber Adequacies in Ration

• Excess fiber
• Low milk production, cow not peaking
• DMI lower than expected
• High milk fat
• Energy content of ration is generally inverse of
  fiber content. High fiber means low energy
• Fiber deficiencies
• Acidosis, off-feed, fluctuating DMI
• Low milk fat
• Cows not chewing cud
• Therefore, there is a tradeoff on particle size

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Particle Size Guidelines

• Feed Top Middle Bottom
• ---------------------- as
  is----------------
• TMR 7 10 45 55 40 - 50
• Haylage 15 - 20 40 - 50 30 40
• Corn Silage
• Processed
• Unprocessed

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Moisture Content

• Plant moisture, rather than kernel milkline,
  should determine when to start chopping
• Due to variation in hybrids and their drydown
  characteristics and differences in growing
  conditions from farm to farm
• Therefore, start checking for moisture when
  kernels are dented and milkline is visible
• Actual whole-plant moisture is the trigger for
  when to start chopping
• Harvesting corn at the right moisture and
  particle size is crucial

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Moisture Content for Harvest Corn Silage

• Bunkers around 33 dry matter
• Piles around 33 dry matter
• Stave Silos about 36 dry matter
• Bags 30-40 dry matter
• If the silage is too dry, it becomes difficult to
  pack

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Kernel Processing Advantages

• May be more digestible in the rumen
• Tears or shears the corn stalk
• Reduces the size of the corn cob and alleviates
  sorting
• Breaks corn kernel allowing more starch to be
  available to the animal
• Better starch digestibility could increase milk
  production slightly

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Kernel Processing Is it beneficial?

• For corn silage that would have mature or hard
  kernels
• If there is enough acres of corn silage to spread
  out the processing cost
• Probably unnecessary if corn silage harvested at
  ideal moisture and ¼ TLC

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TMR Accuracy

• Calibrate Scale at least monthly
• Know feed moisture, watch for snow
• Watch for feed build-up in mixer
• Do not overfill
• Check for uneven distribution at bunk
• Take four samples from bunk. Have each analyzed.
  Particle variation should be

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Corn Silage Harvester Problems

• Problem Possible Causes
• Poor or ragged cut stalks Dull knives, worn
  stationary knife,
• Excessive cob lengths excessive
  stationary-to-cutterhead- knife clearance
• Ragged stubble Improper knife register on row
  crop unit knives not centered on row
• Lack of fan or Hole in spout liner excessive
  blade
• Spout blow to band clearance
• Excessive power Dull knives dull or misaligned
  
• requirement stationary knife

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Cutting Height

• Decision is a balance of getting maximum yield
  vs. higher quality corn silage
• Raising cut height to 18 reduces DM yield about
  15
• Milk/ton increases because more fibrous and less
  digestible portion is left in field
• Milk/acre reduced about 3
• Varies yearly depending on yield and crop quality
• More erosion control from more residue in field?
• Increased quality probably doesnt offset yield
  loss

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TMR Mixer

• Routinely check condition of the TMR Mixer
• Condition of auger flightings
• Condition of knives
• Condition of paddles
• Wear on sides of TMR
• Scales for accuracy

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Management Issues

• Mixing errors can occur from
• batch size too small
• batch size greater than the mixing capacity of
  the mixer
• trying to mix too much hay in the batch
• improper sequencing of ingredients into the mixer
• under mixing or mixing for too short a period of
  time
• over mixing or mixing for too long a period of
  time
• Dr. Randy Schaver, U of WI Dairy Nutritionist

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Management Issues

• Check for particle size on a regular basis --
  forages vary.
• With auger mixers, about 5 minutes of mixing
  should be adequate. Mixing for 15 to 30 minutes
  will result in a TMR that is too fine for the
  cow.
• Analyze particle size often from the TMR.
  Check for uneven distribution at the bunk.
• If the ration on paper appears to meet the
  minimum fiber needs but you are having problems
  with cows going off feed, low fat test, decline
  in production, or DAs, laminitis, and liver
  abscesses, then take a close look at the ration
  physical form consumed by the cow.

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Higher Corn Silage Rations?

• Can go up to 60-65 of total forage dry matter.
• If soybean meal is a good price, more corn silage
  in the diet means less feed cost per day.
• Processed corn silage chopped at ¾ theoretical
  length of cut promotes cud chewing and proper
  rumen function.
• A processed chop length of 3/8 may reduce the
  formation of a fiber mat in the rumen, resulting
  in less effective fiber. This increases risk
  of fresh cow disorders.
• Work with your nutritionist to be sure all other
  ingredients are correct so the ration is properly
  balanced.

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Conclusion

• Any adjustments in harvest cut length, changes
  in ration mixing procedures or other management
  factors must be done with the goal in mind that
  .
• Its what the cow is actually consuming that
  is important for any decision regarding fiber
  length.