Slide 1: Wild Yeasts and Aerobic Stability of Silages and TMR
Wild Yeasts and Aerobic Stability of Silages and TMR Limin Kung, Jr. (lksilage@udel.edu) Professor Emeritus Department of Animal & Food Sciences University of Delaware, Newark 1 Presentation Topics • Metabolism of wild yeasts in silages • Undesirable characteristics of wild yeasts • Effects of yeast
Slide 2: Metabolism of Wild Yeasts in Silage
100 C. rugos a K. exigua C. humilis 80 R. mucilaginos a There is a wide diversity of P. Distribu7on of Species (%) membranifaciens 60 P. des erticola Corn silage P. mans hurica yeasts in silages K. unispor a 40 K. barnettii S. bulderi 20 P. f er mentans C. et hanolica (Santos et al., 2011) S. cerevi
Slide 3: Ideal Fermentation and Good Storage Conditions
Ideal Fermenta,on and Good Storage Condi,ons FermentaHon phase Storage and Feed Out Phases No Air No Air sugars Stable, high quality lactic acid acetic acid pH Days of Ensiling Temperature 5 Ideal Fermentation, Air During Storage or Feed Out Fermentation phase Storage and Feed Out Phases No air Expo
Slide 4: Molds Are Not Responsible for Aerobic Instability
The “Domino Effect” of Air and Wild Yeast on Spoilage in Silages Silage is exposed to air Yeasts ‘wake up’ and degrade lacHc acid Numbers of yeasts increase Highly degradable nutrients are destroyed Heat is produced pH increases Molds/bacteria ‘wake up’ causing further spoilage More heaHng Massive sp
Slide 5: Dry Matter Losses From Good and Poor Silo Management
Dry Matter Losses From Good and Poor Silo Management Losses From Good Management Poor Management Respiration 0-4% 5-15% Fermentation 4-6% 10-20% Seepage 0-1% 5-10% Aerobic instability 5-7% 10-20% during storage/feeding Total 10-15% 20-30% 9 Value of Forage DM Lost From Poor Fermentations and Aerobic
Slide 6: The Negative Relationship Between Number of Yeasts and Aerobic Stability
The Nega(ve Rela(onship Between Number of Yeasts and Aerobic Stability 11 TheoreDcal Growth of Yeasts if Doubling Time = 1-2 h Ø1.6 million cfu/g 100 00000 100 0000 100 000 # of Yeasts 100 00 100 0 100 10 1 0 2 4 6 8 10 12 14 Hours of Growth 12
Slide 7: How Do Initial Populations of Yeasts Affect Time to Spoilage?
How do Initial Populations of Yeasts Affect Time to Spoilage? Spoilage Occurs Here StarHng hi StarHng low 12 h 60 h Time to Spoilage 13 Changes in Yeasts, pH and Temperature of Aerobically Spoiling High Moisture Corn 1 - Yeasts increase 10 2 - Temp increases 50 3 – pH increases 9 45 Yeasts (log cfu/
Slide 8: Distribution of Yeast Counts in Corn Silage
Distribution of Yeast Counts in Corn Silage CVAS Data 35% N=736 30% Ave. = 15,241,867 Percent of samples 25% St. Dev. = 20% Normal Range 72,937,854 15% Undesirable Range 10% 5% 0% 00 0 0 0 0 0 0 0 0 0 0 00 00 00 ,0 , 00 ,0 ,0 00 ,0 ,0 0 0 ,0 <1 10 0 0 0, 00 00 0, 0, 00 10 50 00 ,0 ,0 00 00 ,0 1, 10
Slide 9: Mixing as Little as 10% of Spoiling Silage Can Destabilize a TMR
Silages Are Mixed into TMR- Aerobic Instability of TMR on Farms in the Northeast USA During the Summer ---------TMR aerobic stability------- Total TMR <12 h 12-24 h >24 h number Year 1 8 4 0 12 Year 2 8 5 5 18 Mortes and Kung, 2005 17 Mixing as Little as 10% of Spoiling Silage Can Destabilize a TMR
Slide 10: Why Should We Be Concerned With Aerobically Spoiling Silages?
Why Should We Be Concerned With Aerobically Spoiling Silages? 19 Potential Negative Effects of Yeasts in Silages and TMR • Heating silage in the silo and feed bunk • Reduced intakes • Acidosis like conditions • Milk production and fat depressions 20
Slide 11: The Effect of Feeding a Spoiling TMR to Heifers
Correlation Between Change in Corn Silage Temperature From Aerobic Spoilage and DMI in Goats R = -0.85 P < 0.0001 Gerlach et al. 2013 21 The Effect of Feeding a Spoiling TMR to Heifers • Treatments: – Fresh TMR – Spoiling TMR: Fresh TMR was placed in bins (with holes) in a heated room for ~2 d prior
Slide 12: Experiment Using Fresh and Spoiling Corn Silage Used to Make a TMR
Experiment Using Fresh and Spoiling Corn Silage Used to Make a TMR Item DM, % pH Yeasts, Molds, Aerobic cfu/g cfu/g Stability, hours Fresh corn silage 46 3.85 3.63 3.87 138 Spoiling corn 40 6.57 7.95 7.99 0 silage Steele et al., 2018 University of Delaware 23 Technically, these Nutrient Analysis of
Slide 13: Fermentation Analysis and Numbers of Yeasts in TMRs Fed to Heifers
Fermentation Analysis and Numbers of Yeasts in TMRs Fed to Heifers Item Fresh Spoiling P-Value TMR TMR pH 4.16 5.17 <0.01 WSC, % 2.46 1.85 <0.01 Lactic acid, % 4.17 2.59 <0.01 Acetic acid, % 0.97 0.64 <0.01 Ethanol, % 5.82 6.07 <0.01 Yeasts, log10 cfu/g 5.03 7.82 <0.01 2013 Windle and Kung 107,151 y
Slide 14: Dry Matter Intake of Heifers Fed Fresh vs. Spoiling TMR
Survival of Silage Yeasts in Ruminal Fluid 9.000 8.000 7.000 Yeast Count log cfu/g 6.000 5.000 4.000 3.000 0 12 24 Time (Hours) Merrill and Kung, 2010 27 Dry Matter Intake of Heifers Fed Fresh vs. Aerobically Spoiling TMR 2013 Windle and Kung 12 Dry Matter Intake, kg/d 11.5 11 •Different from Fresh
Slide 15: What Causes the Negative Effect of Feeding Spoiled Silages and TMR?
What Causes the Negative Effect of Feeding Spoiled Silages and TMR? • Production of toxic end products: e.g. mycosis • Alterations in nutritive value: – fatty acid content of yeast cell walls – alterations in biohydrogenation of fatty acids • Organoleptic effects: – Taste – Smell – Hot feel 29 Theor
Slide 16: Is There a Direct Rumen Effect of Wild Yeasts?
Is There a Direct Rumen Effect of Wild Yeasts? Spoilage Yeasts Decrease In Vitro 12-hr Digestibility of NDF from a TMR 45.0 43.9a 42.1ab 42.0 40.7b Note: It is unknown NDF-D (% of NDF) if this happens in 39.0 the cow 36.0 33.9c 33.0 30.0 27.0 Control Log 4.4 Low Log 6.4 Medium LogHigh 8.4 Colony for
Slide 17: Additives to Control Wild Yeasts
Excellent Silo Management is Needed to Maintain High Quality Silage 33 Additives to Control Wild Yeasts • Silage inoculants – L buchneri, L diolivorans, L. hilgardii – Producing moderate levels of acetic acid • Add organic acids – At ensiling – As a TMR saver 34
Slide 18: Pathway of Lactic Acid Degradation by L. buchneri
Pathway of Lactic Acid Degradation by L. buchneri (Oude Elferink et al., 2001) Lactic acid lactaldehyde 1,2-propanediol pyruvic acid CO2 acetyl CoA acetaldehyde ethanol acetic acid à inhibits yeasts à improves aerobic stability 35 Effect of Adding a TMR-Saver Product on the Aerobic Stability of TMR
Slide 19: Improving the Aerobic Stability of Corn Silage Does Not Always Improve TMR
Improving the Aerobic Stability of Corn Silage Does Not Always Result in Improved Stability of the TMR Ø CTRL and Additive treated corn silage from Farm 1 Ø Used ingredients from Farms 1 to 4 to make TMR Corn Silage Stability TMR Stability 25 0 10 0 228a 205a 90 ** 20 0 80 Aerobic stability, h Aerob
Slide 20: pH Affects the Activity of Antifungal Acids
Mixing as Little as 10% of Spoiling Silage Can Destabilize a TMR Steele et al., 2018 University of Delaware 125 F 108 F 86 F 39 pH Affects the Activity of Antifungal Acids pka = pH of acid at half dissociation [A-]=[HA] H+ on H+ off unionized ionized Undissociated Dissociated HA A- R-COOH R-COO pH s
Slide 21: Summary
How Organic Acids Inhibit Wild Yeasts - Effect of pH Gradient on Accumulation of Dissociated Organic Acid Anions (XCOO-) 1) Anion is toxic Out (acidic) Cell membrane In (alkaline) 2) H+ lowers cells pH affects - Anion not permeable enzymes XCOO - H+ --DpH-- XCOO !⃣ H+ #⃣ 3) Cell uses ATP XCOOH to ge
Slide 22: Questions?
Questions? When Are Additives Used to Minimize Wild Yeasts Most Useful? • Silages with high starch, • High DM silages HMC, corn silage, cereal • Silage that will be moved grain silages • Summer feed • Poor bunk life, heating TMR issues • Prolonged storage • Challenged silage removal • Intermediate f