Factors Affecting the Quality Silage After Harvest. Fermentation. Aerobic stability. Aerobic Stability of Silages?

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1 Distribution of Species (%) Distribution of species (%) 9/2/215 Making Milk with Forage: Preserving the Quality of Silage Through Improved Aerobic Stability Limin Kung, Jr. Dairy Nutrition & Silage Fermentation Lab Factors Affecting the Quality Silage After Harvest Type of fermentation What is Aerobic Stability? Definition of aerobic stability: The amount of time a silage remains stable (and does not spoil) after it is exposed to air under defined conditions. Aerobic stability Why Should We Care About the Aerobic Stability of Silages? Silage can undergo a perfect fermentation but if followed by exposure to air, can result in poor quality feed Aerobic spoilage may account for more than 5% of total DM losses in a silo Why Should We Care About the Aerobic Stability of Silages? Spoilage can occur during storage and feedout Spoiled silage can result in Production of undesirable end products Depress nutrient intake and production Reduce farm income Example of an Ideal Fermentation but Poor Aerobic Stability Fermentation No air sugars ph lactic acid acetic acid Days of Ensiling Storage or Feed out Exposure to Air >5C Kung, 2 Misconception Molds are responsible for aerobic instability - This is NOT true! The Sequence of Aerobic Spoilage in Silages 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 2 Highly variable by Massive spoilage feed and farm Whole Plant Maize silage Samples identification Several predominant species C. rugosa K. exigua C. humilis R. mucilaginosa P. membranifaciens P. deserticola P. manshurica K. unispora K. barnettii S. bulderi P. fermentans C. ethanolica S. cerevisiae I. orientalis There are many types of yeasts in silages (Santos et al., 211) High Moisture Maize Sample identification S. dairenensis P. sporocuriosa S. paradoxus R. mucilaginosa S. cariocus P. membranifaciens N. castellii P. manshurica K. unispora S. bulderi P. fermentans S. cerevisiae I. orientalis P. anomala 1

2 9/2/215 All Types of Yeasts in Silages are Undesirable Fermenters Glucose -> ethanol + CO2 Saccharomyces sp. Large DM losses Lactate Utilizers Lactic acid -> CO2 + H2 Candida sp. Hansenula sp. Pichia sp. Aerobically spoils silages low intakes, low nutritive value Lactate Utilizing Yeasts Primarily Initiate Aerobic Spoilage Initiating Spoilage Microbe: Lactating utilizing yeasts Lactic acid -> carbon dioxide and water Spoilage Microbe Sometimes Found in Maize: Acetobacteria Lactic acid -> acetic acid -> carbon dioxide and water Yeasts in Silage are Like Vampire Bats They suck your blood (profits) while you are asleep! = Relationship Between Numbers of Yeasts in Corn Silage and Aerobic Stability 25 Hrs of Stability* Yeasts, log cfu/g 6 8 Number of hours before the silage mass increases 2C above baseline after exposure to air Aerobically Spoiling Silage Often Reaches Temps as High as 5-6 C. Aerobically Spoiled Silage Stored for Months Feeding Spoiled Silages Depresses Intakes and Reduces Digestion in Steers -Spoiled Silage, % of DM- Item DMI, kg/d NDF dig., % Aerobically Spoiling Silage Whitlock and Bolsen, 21 KSU 2

3 Yeasts, log (cfu/ml) Dry Matter Intake, kg/d NDF-D (% of NDF) 9/2/215 Effect of Feeding a Spoiling TMR to Heifers Control vs Spoiling TMR fed to heifers Fed during the winter Spoiling TMR ranged from 35 to 5 C at feeding Nutrient Analysis of TMR Item Fresh TMR Spoiling P-Value TMR DM, % CP, % Soluble protein, % CP ADF, % NDF, % In vitro 3 h NDF-D, % NDF Starch, % Starch-D, % Starch Fermentation Analysis and Numbers of Yeasts in TMRs Fed to Heifers Item Fresh Spoiling P-Value TMR TMR ph <.1 WSC, % <.1 Lactic acid, % <.1 Acetic acid, %.97.6 <.1 Ethanol, % <.1 Yeasts, log 1 cfu/g <.1 17,151 yeasts/g 66,69,35 yeasts/g Numbers of Yeasts in Rumen Fluid 8 7 Different from Fresh TMR, P <.1 (7.39) Dry Matter Intake of Heifers Fed Fresh vs. Aerobically Spoiling TMR 12 11,5 In Vitro 12-hr Digestibility of NDF (% of NDF) from a TMR Incubated with a Spoilage Yeast 5, 3.9 a 2.1 ab 2,.7 b 39, 6 5 (5.62) Fresh TMR Spoiled TMR Treatment 11 1,5 1 9,5 Unspoiled TMR Different from Fresh TMR, P <.1 Spoiled TMR 36, 33, 3, 27, 33.9 c Control Log Low. Medium Log 6. Log High 8. Colony forming units of yeasts/ml of rumen fluid Santos et al., 211 How do initial populations of yeasts affect time to spoilage? Spoilage Occurs Here Starting hi Starting low 12 h 6 h Time to Spoilage How Do We Minimize Spoilage Yeasts in Silages? Management first! Pack quickly Pack tightly Seal quickly Plastic and weighs Facers Additives second... Antifungal compounds There is NO SILVER BULLET Delayed Filling Increases Yeasts and Molds on Corn Forage 1,, 8 1,, 7 1,, 6 1, 5 1, Hirsch and Kung, 1999 yeast molds Hours of Delay Before Filling 3

4 9/2/215 Effect of Packing Density on Yeasts in Lucerne Silage (with homolactic inoculant) Loose pack = 15 kg DM cubic meter Tight pack = 23 kg DM cubic meter 8 Oxygen Barrier Plastic Can Reduce Aerobic Losses During Storage Use of Oxygen Barrier Plastic (HOB film) Reduces DM Losses and Mold Counts in Silage 6 U-T IN-T U-L IN-L Inoculated loose Untreated loose Single Layer PE Double Layer PE OB Film DM loss,% Untreated tight Surface mold growth, cm Inoculated tight Days of Ensiling Lynch and Kung, 21 Single layer =.92 mil plastic Double layer =.92 mil plastic (9.8 mil) OB film = Single layer 1.77 mil oxygen barrier plastic Wilkinson and Rimini (22) 21 BORREANI AND TABACCO Manage the Feeding Face to Minimize Aerobic Spoilahe Keep Air From Penetrating into the Silage Mass -Remove sufficient silage each day to prevent spoilage -Remove more in hot weather and for drier and poorly packed silages -Keep face clean, minimize face damage -Knock down only enough silage to feed Kung, 26 Kung, 26 Kung, 25 Improving the Aerobic Stability of Silages with Additives Microbial inoculants Homolactic acid inoculants not usually recommended if only trying decrease aerobic spoilage Heterolactic acid inoculant containing L. buchneri for improving aerobic stability Chemical additives Potassium sorbate, sodium benzoate Improving Aerobic Stability with Lactobacillus buchneri Naturally occurring bacterium that converts small amounts of lactic acid to acetic acid Acetic acid is highly antifungal - controls yeasts DM loss from heterolactic fermentation is small relative to increased savings of DM loss from aerobic spoilage Effects of L. buchneri + P. pentosaceus on the Aerobic Stability of Maize Silage 5 Replicated Studies from Different Locations Treatment Aerobic Stability, h Control L. buchneri L. buchneri P. pentosaceus Schmidt et al., 26

5 9/2/215 L. buchneri 788 Field Study on Farms in Midwest Spoilage Yeasts in Corn Silages Untreated or Treated with L. buchneri 788 From Dairy Farms in the US Aerobic Stability of Maize Silages Untreated or Treated with L. buchneri 788 From Dairy Farms in the US Corn silage samples Collected from dairy farms 15 farms using no inoculant 16 farms using an inoculant containing either L. buchneri (LB) 788 alone or LB and P. pentosaceus (LBC) b a a,b P <.5 Mari et al., 29 a,b P <.5 Mari et al., 29 Effect of Lasil Fresh on Aerobic Stability ( hours) of Maize and Sorghum Silages (Italy) Item Control LB LP (Lasil Fresh*) (homolactic) Maize Sorghum *Contains L. buchneri 788 Tabacco et al., 27 Effect of Lasil Fresh on Aerobic Stability (hours) of Maize Silages from 37 Farms (Denmark) LB LP Item Control (Lasil Fresh*) (homolactic) January April August *Contains L. buchneri 788 Kristensen et al., 27 Silages That Are Most Prone to Aerobic Spoilage High moisture maize Maize and barley silage Silages with high DM (>%DM) Silage fed during warm weather (summer, etc.) Silages fed out slowly Silage that will be moved between silos Silage fed from intermediate feeding piles L. Kung, Univ. of Delaware Summary In order to maintain forage quality, silages should ferment well and be aerobically stable Yeasts that metabolize lactic acid under aerobic conditions are the primary initiators of spoilage Basic silo management and various additives have the potential to minimize aerobic spoilage of silages 5