HARVESTED FORAGES Silage pp. 253-260

ENSILING What is ensiling? Storing a forage or grain crop at a relatively high moisture concentration in anerobic conditions to have it undergo fermentation to lactic acid. Lactic acid will preserve silage as long as the silage isn’t exposed to oxygen

WHY ENSILE?

ENSILING Goals Avoid Decrease pH of ensiled crop to <4 Increase lactic acid concentration of ensiled crop to >4% of DM Requires anerobic conditions Avoid Molding and heating of crop Occurs if forage is exposed to oxygen Forage DM% > 60% Butyric acid production, protein degradation, and seepage from silage Forage DM% < 30% Dependent of forage species

APPROPRIATE MATURITY AND DM PERCENTAGE FOR ENSILING Desired for ensiling Crop Maturity DM% Whole plant corn 50% milk line stage on grain 30-40% Grain or forage sorghum Medium dough stage of grain Small grains Late boot stage 35-45% Grasses Boot stage 40-50% Requires wilting Legumes Late bud stage 40-50% Requires wilting

THE ENSILING PROCESS

THE ENSILING PROCESS Aerobic phase Organisms Nutrient Metabolism Plant enzymes Aerobic bacteria and yeasts Nutrient Metabolism Sugars oxidized to CO2 Changes in forage O2 is consumed and CO2 produced Temperature increases to 115oF Sugars decreased Length of change Desire < 24 hours Extended by: Too dry Long chop length Slow filling Poor packing No cover In extended, results in: Excessive heating Increased ADIN

Heterofermentative phase Organisms Heterofermentative lactic acid bacteria Nutrient Metabolism Sugars fermented to acetic acid, lactic acid, and CO2 Changes in forage Increased concentration of acetic acid and lactic acid pH decreased to 5.0 Sugars decreased Length of change Desire < 1 week Extended by: Forage being too wet If pH never drops to 5 Causes Forage too wet Inadequate sugars Results Clostridium bacteria growth Butyric acid production Protein degradation to NH3 and other forms of NPN

Homofermentative phase Organisms Homofermentative lactic acid bacteria Nutrient Metabolism Sugars fermented to lactic acid Changes in forage Increased concentration of lactic acid 6 to 8% of DM pH decreased to 3.8 to 4.2 Sugars decreased Length of change Desire < 2 weeks

Storage phase If not exposed to oxygen If exposed to oxygen Forage well-preserved with little change in composition If exposed to oxygen Growth of aerobic bacteria and mold Results in heating, nutrient loss, and decreased palatability Growth of listeria bacteria Results in listeriosis Encephalitis Metritis and abortion

Feedout phase Exposes silage to oxygen Growth of aerobic bacteria and molds Results: Heating Loss of lactic acid Nutrient loss Losses minimized by adequate feedout rate Match diameter of tower silos or width of bunker silos to herd size Season Silo type Winter Summer Inches removed/day Tower 2 4 Bunker 6

SILO TYPES Tower Bunker or trench Silo bags 30 to 50% DM Easy to pack Good for hay crop or corn silage Minimal exposed surface Expensive Bunker or trench 30 to 40% DM Difficult to pack Not desirable for hay crop silage Requires polyethylene cover Considerable surface area at feeding Less expensive than towers Silo bags Versatile Bags subject to punctures and tears Relatively low capital investment

Big bale silage Limitations 40 to 60% DM Advantages Inexpensive Allows small amounts of forage ensiled Transportable No specialized equipment beyond wrapper Limitations Some large balers can not bale high moisture forage Long forage more difficult to ensile than chopped forage Bales are heavy Plastic wrap subject to puncture and tears Disposal of plastic

DM LOSSES FROM DIFFERENT SILO TYPES Concrete tower Bunker Bag Round bale DM losses, % Respiration 4 Harvesting 2 Storage 9 15 7 18 Feedout Total 17 25 30

PROPERTIES OF HIGH QUALITY SILAGE Silage pH 3.6 – 4.2 Lactic acid 4-8% of DM Acetic acid <2% Butyric acid <0.1% Nitrogen fractions Ammonia nitrogen <5% of total N ADIN <12% of total N Microbial assay Total aerobic bacteria <100,000 cfu/gm silage Molds

MAKING HIGH QUALITY SILAGE Harvest at appropriate maturity and moisture Set chop length Fill silo as rapidly as possible Pack, pack and pack some more Cover silos immediately 6-mil plastic Weight on bunker silos Feedout Adequate rate Maintain clean face Crop Length of chop Hay crop ¼” Unprocessed corn silage 3/8 to ½” Processed corn silage (Kernel processor) ¾”

SILAGE ADDITIVES Water Bacterial inoculants Enzymes Added if forage moisture is inadequate Requires 5 gallons/ton to change DM by 1% Bacterial inoculants Lactobacilli Add a minimum of 100,000 cfu/gm fresh forage Useful to: Improve lactic acid production if forage is harvested at excessive moisture concentration Prevent aerobic damage at feedout or in feed bunk Enzymes Cellulases, hemicellulases, amylases, pectinases Increase sugars to improve lactic acid production No consistent improvement

NPN sources Acids Sugar sources Used with corn, sorghum, and cereal silages Types Anhydrous ammonia at 5 to 10 lb/ton fresh forage Urea at 10 to 20 lb/ton fresh forage Advantages Increases crude protein content Increases aerobic stability at feedout Acids Propionic or formic acid Application: 10 to 20 lb/ton fresh forage Applied to forage that is either too wet or too dry Formic acid causes a rapid decrease in pH if too wet Propionic acid inhibits mold growth in too dry Sugar sources Molasses, whey, or grain Added to crops with low concentration of soluble sugars Grasses and legumes Increases lactic acid concentration Loss of energy from the source

NUTRITIONAL VALUE OF HIGH QUALITY SILAGE Lower feed consumption than fresh crop or hay Lower NDF, but comparable ADF to fresh crop or hay Comparable net energy concentration to fresh crop or hay Comparable crude protein concentration to fresh crop, but greater than hay Greater proportion of crude protein will be degradable in the rumen than fresh crop or hay Higher carotene content than hay