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Forage Fermentation: How to Make Good Silage

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Dr. Limin Kung of the University of Delaware presented this information for DAIReXNET on February 17, 2014. The recorded webinar can be found at http://www.extension.org/pages/15830/archived-dairy-cattle-webinars#.UwPQJc4gvZc.

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Forage Fermentation: How to Make Good Silage

  1. 1. Forage Fermentation: How to Make Good Silage Limin Kung, Jr. Dairy Nutrition & Silage Fermentation Lab
  2. 2. Definition of a high quality silage/forage Nutrient recovery  High nutritive concentration    (CP, starch, etc.) High digestibility by rumen microbes
  3. 3. Harvest Quality and Silo Management Have Profound Effects on Silage Quality at Feeding Poor quality forage from field-> Poor harvest and silo management -> = Poor quality silage at feeding Poor quality forage at harvest -> Excellent harvest and silo management -> = Poor quality silage at feeding High quality forage at harvest -> Poor harvest and silo management -> = Poor quality silage at feeding High quality forage at harvest -> Excellent harvest and silo management -> = Excellent quality silage at feeding Kung, 2001
  4. 4. Value of Potential Forage Loss in the Silo –$35/t for Corn Silage Tons of Silage/yr ----- DM Losses----- <10% 15% 20% 1,000 3,500 5,250 7,000 2,000 7,000 10,500 14,000 3,000 10,500 15,750 21,000 Good Poor Management Expect losses in milk production and/or greater concentrate costs when feeding poorer silage L. Kung, Jr., University of Delaware
  5. 5. Challenges with Alfalfa Silage       High buffering capacity -> slow fermentation Difficult to wilt quickly Easily goes clostridial when DM is low (<30%) Substrate for fermentation can be limiting during cloudy weather, heavy rains, prolonged wilts Difficult to pack when dry Easily heat damaged at higher DM (>50%) L. Kung, Jr., University of Delaware
  6. 6. Help with Alfalfa Silage  Minimize wilting time (wide swath?)  Maximize dry down hours during daylight  Wilt to at least 35% DM  Avoid excessive DM (not more than 50% DM)  Avoid being rained on  Avoid mowing and harvest under cloudy conditions L. Kung, Jr., University of Delaware
  7. 7. Consequences of Extreme DM on Alfalfa and Grass Silages Too Wet (<30%) Too Dry (>45-50%) -Clostridia -Tough to pack protein degradation -Poor stability DM/energy loss -Heat damage CP low digestibility leading to low butyric acid/amines digestibility -Seepage L. Kung, Jr., University of Delaware
  8. 8. Consequences of Harvesting Corn for Silage at Extreme DMs Too Early Optimum Too Late (<28-30% DM) (>40% DM) Low [starch] Low starch digestion Low [energy] 32-36% DM Low acid production Excess [acid] Tough to pack High acetic acid Poor aerobic stability Seepage L. Kung, Jr., University of Delaware
  9. 9. Optimum Harvest Time for Corn Silage ~32 to 36% whole plant DM Good starch content and digestibility Good fiber digestion Good packing in the silo L. Kung, Jr., University of Delaware
  10. 10. Effect of Corn Silage Maturity on Starch Digestion in the Total Tract adopted from Shaver, 2002 100 100 % Starch 95 Digestion 90 90 Unprocessed 80 80 48 .8 46 45 .6 45 44 43 42 .8 40 .6 39 .4 38 37 .2 35 40 Whole Plant Corn DM% 34 .6 33 .4 32 31 .2 30 36 65 .8 70 70 black layer .4 ½ milk line .2 75 30 St arch dig. % 85 Dry Mat t er % *Based on data of Bal et al., 2000; Dhiman et al., 2000; Rojas-Bourrillon et al.1987
  11. 11. Set Chop Length at Harvest!! Item C. Silage* Processed** Top 3-8% 5-15% Middle 45-65 >50 Lower 20-30 <30 Pan <5 <5 *Heinrichs, PSU **Hutjens, UI
  12. 12. Processing for Corn Silage Cracks the kernel open to expose starch -> + digestion Reduces TMR sorting Improves silage packing L. Kung, Jr., University of Delaware
  13. 13. Fecal Starch and Digestibility Goal is to have less than 3-4% fecal starch 1%-unit decrease in fecal starch ~ 1 pound more milk Range in starch: 2.3 – 22.4% (Ferguson, 2006)
  14. 14. Corn Silage Processing Score % of starch passing through a coarse screen (>4.75 mm) Processing Rank Greater than 70% Optimum 70% to 50% Average Less than 50% Inadequately processed Mertens, 2003
  15. 15. 4.75 mm is 1/5 of an inch
  16. 16. Thumb Rules for Assessing the Degree of Processing 4.75 mm    > 95% of kernels cracked (70% equal to or smaller than 1/3 to ¼ kernel size) Nicking and crushing are not enough Cob should be broken to >8 pieces diameter hole These pieces would Not pass through a 4.75 mm hole…. Thus, they are not processed enough! L. Kung, Jr., University of Delaware
  17. 17. Separate Kernels from Forage in a Bucket of Water to Assess Kernel Processing Kung, 2001
  18. 18. Post Processor? L. Kung, Jr., University of Delaware
  19. 19. The Goals of Making Silage Front-end Back-end Rapid preservation for maximum recovery of nutrients Continued preservation of nutrients and excellent “shelf life”
  20. 20. Microbes at work in silage – silage making is like a war – good bugs must win!  “Good bugs”  Lactic acid bacteria heterofermentative  homofermentative   “Bad bugs” Yeasts  Molds  Clostridia  Enterobacteria  Kung, 2001
  21. 21. Conditions Front end fermentation No Air sugars Back end storage No Air Stable, high quality lactic acid acetic acid pH > 45 C 35 C Days of Ensiling Kung, 2001
  22. 22. However…  A good front end fermentation does not automatically lead to stability during storage and feed out (backend)  A high concentration of lactic acid and/or low pH alone does not automatically equate to a stabile if silage is exposed to air
  23. 23. Ideal Fermentation but Poor Storage Conditions Front end fermentation Back end storage No air Exposure to Air sugars lactic acid acetic acid pH >120 F Days of Ensiling Kung, 2001 105 F
  24. 24. The “Domino Effect” From Air on Aerobic Spoilage – Bad Bugs Silage is exposed to air Yeasts ‘wake up’ and degrade lactic acid Numbers of yeasts increase Highly degradable nutrients are destroyed Heat is produced pH increases Molds/bacteria ‘wake up’ causing further spoilage More heating Massive spoilage L. Kung, Jr., University of Delaware
  25. 25. The Negative Relationship Between Number of Yeasts and Aerobic Stability 200 Hours Of 160 Stability Before 120 Spoilage o o o o 80 o o o o o o 40 0 1000 Kung, University of Delaware o o o 10000 100000 Yeast, cfu/g o o 1000000
  26. 26. Changes in DMI When Heifers are Fed Aerobically Spoiling Feed Der Bedrosian et al., 2012 a b 107,151 yeast/g
  27. 27. Undesirable Clostridial Fermentation Front end fermentation Back end storage Poor quality forage High NH3 and butyric acid Forage too wet Low sugars Clostridia pH sugars acetic acid lactic acid >120 F 105 F Days of Ensiling butyric acid
  28. 28. Silo Filling •Fill quickly •Pack tightly •14-16 lb DM/ft3 CS (225-260 kg DM/m3) •15-17 lb DM/ft3 AS (240-270 kg DM/m3) •6-8 inch (15-20 cm) layers •Heavy tractors
  29. 29. Plastic on the Sidewalls Greenfield, 2003
  30. 30. Cover With Plastic and Tires Immediately     White plastic better than black 6 is better than 4 mil Small bunks – consider 2 layers? (thin layer on bottom is best) More weight on seams/edges L. Kung, Jr., University of Delaware
  31. 31. Oxygen Barrier Plastics Kung and McDonell, 2005
  32. 32. No Chia-Pet Covers!!! Kung, 2007
  33. 33. Check the teeth on your baggers Sharp teeth = -faster and tighter bagging -cleaner cuts on forage (less juicing) L. Kung, Jr., University of Delaware
  34. 34. Keep Plastic Down at the Feeding Face Kung, 2006 Kung, 2006
  35. 35. Face Management - Remove a minimum ??? inch/d - Remove more in hot weather and for drier/poorly packed silages - Keep face clean, minimize face damage - Knock down only enough silage to feed
  36. 36. “The Management Disconnect” This farm was so happy that they were using a face shaver! Face Shavers  (+) Most useful when density is low and/or feed rate is slow  May save 3% in DM  Savings in animal performance?  (-) Longer feeding time L. Kung, Jr., University of Delaware
  37. 37. Microbial Inoculants Can Improve Silage Fermentation and Aerobic Stability  Help at the Front – Homolactic acid bacteria     Help at the Back – Lactobacillus buchneri     Faster fermentation Reduce clostridia Improved DM/energy recovery Improved aerobic stability Fresher feed Less spoiling Dual purpose – Combination of the above
  38. 38. Approaches For Using Silage Inoculants – Tools For Maintaining Good Fermentations 1. Preventing a clostridial fermentation - wet alfalfa and grasses - quick attainment of a low pH - conventional homolactic acid bacteria 2. Improving aerobic stability - HMC and corn silages - L. buchneri products 3. Making a good fermentation better - improvements in DM recovery Modified from Muck 2008
  39. 39. General Inoculant Recommendations  By crop     Alfalfa and grasss -> Ho* (>40% DM -> LbC**) Corn silage -> Ho or LbC (if aerobic challenges) HMC -> LbC By DM   < 30% DM -> Ho (avoid LB) > 40% DM -> LbC *Ho = homolactic acid bacteria based additive **LbC = L. buchneri + homolactic acid bacteria
  40. 40. Managing Your Inoculants  Calibrate applicators frequently  Optimize distribution  Liquid applied is better in drier (>40% DM) forages  Do not mix inoculants with hot water  Keep water temp in tanks < 95-100 F
  41. 41. Numbers of Viable Bacteria Were Lower in Tanks with High Water Temperatures r2 = 0.39 P < 0.01 16 Windle and Kung, University of Delaware, 2013 27 38 49
  42. 42. Summary      Forage quality and silo management have profound effects on net farm income Harvest forage crops at optimum maturity Follow best management practices for processing and storage Use tools available to measure standards Use inoculants best suited for your needs
  43. 43. THANK YOU!!!! LKSILAGE@UDEL.EDU http://ag.udel.edu/anfs/faculty/Kung.html

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