Corn Silage Inoculants Review

March 26, 2018 | Author: Mevlut Gunal | Category: Fermentation, Lactic Acid, Cellular Respiration, Food & Wine, Food And Drink


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Corn Silage InoculantsReview Gbola Adesogan Department of Animal Sciences IFAS, University of Florida Outline  Silage fermentation process  Chemical additives – Organic acid additives – Ammonia (urea)  Inoculants – Definition – Roles – Types – Effectiveness  Take home messages Chemical changes during fermentation 1. Anaerobic bacteria ferment sugars to volatile acids • e.g. lactic, acetic & butyric acids 2. Acids pickle the forage and inhibit undesirable microbes 3. Protein is partially degraded into ammonia 4. These processes can cause DM losses (effluent / seepage) Sugars Chemical changes during fermentation  Pickling / fermentation of the forage Days 21 CP Lactate Ammonia Acetic acid Butyric acid 20 15 10 5 Scale (%) 1 pH CROP SILAGE Fermentation pathways Product Nutrient Losses Substrate (Microbe) Fermentation 2 x Lactic acid (Low pH) Low  Glucose (L. plantarum) Homo- fermentative 1 x Lactic & acetic acids, ethanol & CO 2 (Moderate pH) Moderate  Glucose (L. buchneri) Hetero- fermentative V. high Ethanol, CO 2  Glucose, lactic acid (Yeasts & molds) Aerobic spoilage Butyric acid + CO 2 (High pH) High  Lactic acid (Clostridia) Secondary fermentation 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 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 Inoculants  Definition Additives containing bacteria selected to grow quickly and dominate the bacterial population in the silage  Types 1. 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%) 2. Newer inoculants (heterofermentative) – Aerobic stability enhancers – e.g. L. buchneri Effectiveness of inoculants 0 20 40 60 (Muck & Kung, 1997) n = 221 233 148 34 39 82 35 Effectiveness of inoculants in different silages Fermentation 60% Intake 28% Gain 53% Milk production 47% (Muck, 2002) Effectiveness of inoculants in different silages % t r i a l s w i t h l o w e r p H 0 20 40 60 Alfalfa Grass Corn Sm. Grain (Muck and Kung, 1997) Epiphytic bacteria on Standing Crops 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 C o r n P . R y e g r a s s R y e g r a s s H . R y e g r a s s A l f a l f a Homoferm. Heteroferm. Entero (Andrieu & Gouet, 1990) 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) Forage factors affecting inoculant action  Forage epiphytic microbial population  Forage sugar content  Forage buffering capacity  Forage maturity stage  Forage hybrid / variety 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  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) Inoculants are most effective for corn silage for: 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 1. “No problemo re-bagging. Would very much recommend it”. 1. “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”. 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 Effect of inoculants on aerobic stability of corn silage (Ranjit & Kung, 2000) Inoculant Application rate (cfu/g) Acronym Control 0 Control Lactobacillus buchneri 100,000 LB Mod Lactobacillus buchneri 1,000,000 LB High Lactobacillus plantarum 1 1,000,000 LP 1 Lactobacillus plantarum 2 1,000,000 LP 2 Storage-mate NA Store-mate Effect of inoculants on composition 0 2.5 5 7.5 10 Acetate Lactate WSC (sugars) % D M C o n t r o l L B x M o d L B x H i g h L P - 1 L P - 2 S t o r e - m a t e Yeasts (log 10 cfu) Effect of inoculants on aerobic stability A e r o b i c s t a b i l i t y ( h o u r s ) 27 36 >900 32.8 33 38 C o n t r o l L B x M o d L B x H i g h L P - 1 L P - 2 S t o r e - m a t e (Ranjit & Kung, 2000) 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 Silage Additive Regulators Countries with pre-market screening of additives  UK UKASTA   Canada Ag. Canada   USA None  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. “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” Recent quote: Beware, inoculants are useful but they are neither: A substitute for bad management magic potions Take Home Messages  Harvest promptly – (35%DM or 1/3-2/3 milk line) Sharp knives, chop length Unprocessed (1/4 –3/8 inch) Processed (3/4 inch) Take Home Messages  Fill bunker promptly  Pack, pack and pack again  Seal immediately & properly + tires Take Home Messages  Manage the silo face – Feedout quickly (6 inches/day) – The narrower the bunker, the better – Minimal disturbance – Heat loss = production volatilized Questions Effect of delayed sealing on fermentation (Uriate et al., 2001) Day Control Additive-treated Control Immediate seal Delayed (48h) seal 0h seal Delayed (48h) seal pH at opening 3.7 3.7 3.5 3.6 pH 4 days later 3.6 8.0 3.7 8.2 Lactic acid at opening (% DM) 4.5 4.9 4.1 4.5 Lactic acid 4 days later 4.4 0.3 3.9 1.5 Effect of delayed sealing on stability & yeasts (Uriate et al., 2001) Day Control Additive-treated Control Immediate seal Delayed (48h) seal 0h seal Delayed (48h) seal Lactate utilizing Yeasts at opening 4.9 5.7 5.0 5.5 Lactate utilizing Yeasts 4 days later 8.2 9.4 9.0 8.7 Aerobic stability (hours) 113 65 137 89 Ensiling losses- Source % Net Energy lost Respiration 1-2 Wilting 2-5 Heterofermentative bacteria 4 Secondary Fermentation 0-5 Effluent 5-7 Aerobic spoilage in the silo 0-10 Aerobic spoilage at feedout 0-15 (McDonalds et al., 1991) 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 Effect of temperature on corn silage pH 37 O C 28 O C Target pH (Weinberg et al., 2001) Effect of temperature on corn silage pH Inoc, 24 O C Control 24 O C Inoc, 41 O C (Weinberg et al., 2001)  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. Temperature matters! Fermentation vs. stability  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
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