Corn Silage Inoculants Review

1. Corn Silage Inoculants Review Gbola Adesogan Department of Animal Sciences IFAS, University of Florida

2. Outline • Silage fermentation process • Chemical additives • Organic acid additives • Ammonia (urea) • Inoculants • Definition • Roles • Types • Effectiveness • Take home messages

3. Chemical changes during fermentation • Anaerobic bacteria ferment sugars to volatile acids • e.g. lactic, acetic & butyric acids • Acids pickle the forage and inhibit undesirable microbes • Protein is partially degraded into ammonia • These processes can cause DM losses (effluent / seepage)

4. Chemical changes during fermentation Sugars CP Lactate pH Ammonia Acetic acid Butyric acid Scale (%) • Pickling / fermentation of the forage 20 15 10 5 1 21 Days CROP SILAGE

5. Fermentation pathways Homo-fermentative Glucose(L. plantarum)  2 x Lactic acid (Low pH) Low Hetero-fermentative Glucose (L. buchneri)  1 x Lactic & acetic acids, ethanol & CO2 (Moderate pH) Moderate Secondary fermentation Lactic acid (Clostridia)  Butyric acid + CO2 (High pH) High Aerobic spoilage Glucose, lactic acid (Yeasts & molds)  Ethanol, CO2 V. high Fermentation Substrate (Microbe) Product Nutrient Losses

6. Organic acids • Role • Rapidly reduce pH; hence inhibit undesirable microbes • Antifungal – hence enhance aerobic stability • Types • Pure acids e.g. formic, propionic, acetic & benzoic acids. • Effective but caustic & hazardous • Buffered organic acids – Ca & Na salts of pure acids • Less caustic & safer to handle

7. Ammonia (urea) • Role • Alkaline and antifungal in nature • Improves aerobic stability • Contributes CP • Concerns • Narrow harvest window • If < 60% moisture – volatilization • If >70% moisture – N loss in effluent • May hinder fermentation & increase DM losses • V. caustic, protective clothing required • Ammonia poisoning

8. Inoculants • DefinitionAdditives containing bacteria selected to grow quickly and dominate the bacterial population in the silage • Types • Traditional (homofermentative) inoculants • e.g. Lactobacillus plantarum •  lactic acid &  pH, acetic & butyric acids •  losses of DM (1-3%), sugar and protein • May increase fiber digestion & animal performance (3-5%) • Newer inoculants (heterofermentative) • Aerobic stability enhancers • e.g. L. buchneri

9. Effectiveness of inoculants n = 221 233 148 60 34 82 39 40 35 % Positive trials 20 0 pH Ammonia DM loss Lactic/Acetic Bunk Life DM digestibility Fiber digestibility (Muck & Kung, 1997)

10. Effectiveness of inoculants in different silages (Muck, 2002)

11. Effectiveness of inoculants in different silages 60 40 % trials with lower pH 20 0 Alfalfa Grass Corn Sm. Grain (Muck and Kung, 1997)

12. Epiphytic bacteria on Standing Crops (Andrieu & Gouet, 1990)

13. Contrasting views on inoculants • “Results from over 200 laboratory-scale silo studies, indicated bacterial inoculants were beneficial in over 90% of the trials. A good-quality, effective inoculant should be applied to every load of forage ensiled!” (Bolsen, 1997) • Reviewed corn silage inoculants articles for 5 years “We don’t see enough benefits to recommend inoculants for corn silage”(Muck, 2001)

14. Forage factors affecting inoculant action • Forage epiphytic microbial population • Forage sugar content • Forage buffering capacity • Forage maturity stage • Forage hybrid / variety

15. Inoculant factors affecting inoculant action • Bacteria strain and composition • Bacteria viability • Inoculant application rate • > 100,000 live bacteria (cfu)/g or > 90 billion bacteria / ton • Inoculant form • Liquid inoculants act faster & more evenly distributed • Must use within 24h & inactivated by chlorinated water • All inoculants are not created equal

16. Inoculants are most effective for corn silage for: • Fermentation enhancement when epiphytic bacteria are compromised - • Immediately after frost • Dry crop • Immature crop Use traditional homofermentative inoculants • Aerobic stability enhancement • Homofermentative inoculants reduce acetate and propionate, hence are less effective Use L. buchneri (heterofermentative)

17. QUESTION:Does anyone know if I can re-bag corn silage? We need more pavement and the bag is in the way. Would it work better to put it in a bunker silo? ANSWERS • “No problemo re-bagging. Would very much recommend it”. • “We rebagged some corn silage two years ago and were left with a horrible pile of garbage.  The excellent corn silage had become inedible. Right now we're using it as part of our compost program”.   

18. Bunk /Aerobic spoilage • More prevalent in corn & small grain silages • Can cause < 50% of losses in silage DM • Spoilage of the top 1m = $500 to $2500 (Bolsen, 1997) • Causes • Air entry into good silage • Air pockets in poor silage • Untidy silo faces • Slow feedout • Effects • Reduce intake • Reduce nutritive value • Produce mycotoxins

19. Effect of inoculants on aerobic stability of corn silage (Ranjit & Kung, 2000)

20. Effect of inoculants on composition Acetate Yeasts (log10cfu) Lactate WSC (sugars) LP-2 LP -1 Store- mate Control LB x Mod LB x High 10 7.5 5 % DM 2.5 0

21. Effect of inoculants on aerobic stability >900 Aerobic stability (hours) 38 36 33 32.8 27 LP-2 LP -1 Store- mate Control LB x Mod LB x High (Ranjit & Kung, 2000)

22. L. Buchneri Summary • Benefits • Enhanced aerobic stability • No adverse effects on intake (observed so far) • Limitations • More nutrient losses than homofermentative inoculants • Future work • Combining front (homofermentative) & back end (heterofermentative) inoculants

23. Silage Additive Regulators Countries with pre-market screening of additives • UK UKASTA  • Canada Ag. Canada  • USA None 

24. Take Home Messages • Only use inoculants with • Independent research-attested track record • >90 billion live bacteria / ton • L. plantarum for fermentation enhancement • L. buchneri for bunk life enhancement • Don’t choose by cost (35 cents to $1 per ton) • Use only corn silage inoculants for corn silage • Apply at chopper, not into wagon or at bunker • Store in a cool, dry place • Once diluted, use within 24 h.

25. Recent quote: “Silage producers have long recognized the positive effects of using an inoculant to insure the proper transformation of forage into a palatable and digestible feedstuff” • Beware, inoculants are useful but they are neither: • A substitute for bad management • magic potions

26. Take Home Messages • Sharp knives, chop length • Unprocessed (1/4 –3/8 inch) • Processed (3/4 inch) • Harvest promptly – (35%DM or 1/3-2/3 milk line)

27. Take Home Messages • Fill bunker promptly • Pack, pack and pack again • Seal immediately & properly + tires

28. Take Home Messages • Manage the silo face • Feedout quickly (6 inches/day) • The narrower the bunker, the better • Minimal disturbance • Heat loss = production volatilized

29. Questions

30. Effect of delayed sealing on fermentation (Uriate et al., 2001)

31. Effect of delayed sealing on stability & yeasts (Uriate et al., 2001)

32. Ensiling losses- (McDonalds et al., 1991)

33. How does buchneri work • Uses heterolactic fermentation – • More acetate produced • Acetate is an anti-fungal agent • Inhibits-spoilage causing yeasts & moulds • Disadvantages of heterolactic fermentation • Depressed lactate production & higher nutrient losses • Depression in intake if excess acetate is produced

34. Effect of temperature on corn silage pH 37OC Target pH 28OC (Weinberg et al., 2001)

35. Effect of temperature on corn silage pH Inoc, 41OC Inoc, 24OC Control 24OC (Weinberg et al., 2001)

36. Temperature matters! • Inoculated silages may spoil more than respective control silages at high temperatures which inhibit the growth of inoculant bacteria. • Special care should be taken during silage making and unloading in warm climates • Florida corn silage producers must do better than average.

37. Traditional view Conventional inoculants (homofermentative) enhance fermentation but often reduce bunk life Cause = Reduced acetic & propionic acid Emerging view L. buchneri (heterofermentative) inoculants can improve bunk life Fermentation vs. stability