SILAGE MAKING Assoc. Prof. Dr. István HULLÁR (2010.)

to make forage storable; inhibition of nutrient loss caused by FORAGE PRESERVATION AIM: to make forage storable;  inhibition of nutrient loss caused by   action of plant enzymes microbes.

METHODS OF PRESERVATION 1. Haymaking: preservation is based on drying; 2. Silage Making: preservation is based on an acidification.

SILAGE MAKING Why? Preservation of forage high in moisture without drying; How to do that? Based on an acidification due to lactic acid fermentation under anaerobic conditions.

TERMS Silage: forage of high moisture content conserved by anaerobic fermentation (DM: 30-35%); Haylage: low-moisture silage (wilted forage) - (DM: 40-50%); Ensilage: silage making (process); Silo: the place for herbal fermentation.

METHOD OF SILAGE MAKING 1. Harvesting, chopping 2. Filling of the silo 3. Pressing to exclude air (oxygen). 4. Covering to - achieve and maintain anaerobic conditions, - exclude aerobic microbes, - develop lactic acid bacteria.

PRICIPLES OF PRESERVATION Microbial fermentation of soluble carbohydrates  Production of organic acids (1.5% Lactic acid, 0.5% Acetic acid, less than 0.1% Butiric acid) Acids produced reduce the pH up to 4.2 (corn silage) Acidity inhibits further fermentation Silage is ready.

PHASES OF FERMENTATION 1st phase - plant respiratory enzyme activity as long as conditions are aerobic, - production of CO2 decreases the pH, - destruction of plant tissues, - loss of cell integrity and turgor.

PHASES OF FERMENTATION 2nd phase (phase of fermentation: 10-20 days) - aerob micro organisms are replaced by anaerobs, - number of lactic acid bacteria is increasing, - mobilization of soluble carbohydrates, - production of lactic acid, - decrement of the pH; 3rd phase (phase of standstill) - pH is standard, - no more microbial activity.

Some fermentation pathways in ensilage Lactic acid bacteria  production of lactic acid 1. Homofermentative 1 mol glucose  2 mol lactic acid (Lactobacillus plantarum, L. casei, Pediococcus cerevisiae, etc.) 2. Heterofermentative 1 mol glucose  1 mol lactic acid + ethanol + CO2 (L. brevis, L. buchneri, etc.).

Some fermentation pathways in ensilage Coli-Aerogenes-Group (optimum pH: 7.0) - fakultative anaerobes, - fermentation of carbohydrates  acetic acid + CO2  - less palatable, - waste of carbohydrates.

Some fermentation pathways in ensilage Clostridia (pH opt. 7.0-7.5)  Butiric acid; Substrates: - Carbohydrates  Butiric acid  waste of carbohydrates, - Lactic acid  Butiric acid  worse dissociation (higher pH); - Amino acids  NH3 (buffer)  higher pH + toxic amines (Lys → Cadaverine; Arg → Putresscine; Tyr → Tyramine).

Some fermentation pathways in ensilage Yeasts (pH opt. 5.0); Substrates: - Lactic acid, - sugars; Products: alcohol + CO2 + H2O.

Some fermentation pathways in ensilage Moulds Substrates: - carbohydrates, - proteins; Consequences: - waste of nutrients, - lower feed intake.

Factors influencing the fermentation 1. DM content of green forages - Corn silage: 30-35% - Haylage: 40-50% (wilted forage) 2. Amount of easily fermentable carbohydrates - corn silage: 290 g/kg (easily fermentable), - grass silage: 120 g/kg (moderately fermentable), - alfalfa silage: 65 g/kg (difficultly fermentable); 3. Crude fibre → elastic (pressing is difficult); 4. Temperature (27-38oC).

Factors influencing the fermentation 5. Buffering capacity (Bc) Amount of Lactic acid (g) required to reduce pH of 1 kg DM to 4.0; - BcCorn silage: 40 g/kg DM; - BcAlfalfa: 90 g/kg DM; Factors increasing the Buffering capacity a) high level of CP  NH3, b) alkali metals (Ca, Mg).

Losses in Silage Making a) Oxidation losses Action of plant and microbial enzymes on substrates; b) Fermentation losses: harmful microbes; c) Effluent losses (seepage): - initial moisture content of the crop; - rain (uncovered silo).

TYPES of SILOS 3. Plastic Bag Silos. 1. Horizontal Silos. 2. Tower (upright) Silos. 3. Plastic Bag Silos.

SILAGE ADDITIVES Molasses, Dried sugar beet pulp, Cereal grains. 1. FERMENTABLE CARBOHYDRATES Molasses, Dried sugar beet pulp, Cereal grains.

SILAGE ADDITIVES 2. PRESERVATIVES Mineral acids (hydrochloric, sulfuric, and phosphoric acids or the mixture of them),  setting up the required pH; Organic acids: formic acid, propionic acid, Disadvantages of their use: - can disturb the mineral metabolism of the host, - danger in their use (corrosive, difficult to handle).

SILAGE ADDITIVES Bacteria cultures (lactic acid producers) 3. BIOLOGICAL ADDITIVES Bacteria cultures (lactic acid producers) (e.g. Lactobacillus acidophilus, Streptococcus faecium).

EVALUATION OF SILAGE QUALITY 1. Subjective methods (visual appearance) (colour, smell, taste, texture) - colour: green vs. brown (darker colour indicates heat damage), - smell: aromatic (butyric acid is stinking), - taste: sweet vs. acidic (acetic acid causes acidic taste, reduces the feed intake), - texture: firm, preservation of particle’s structure.

EVALUATION OF SILAGE QUALITY 2. Objective methods - chemical compositions (DM, CP, EE, CF, NFE, NDF, ADF, ADL), - acidity (pH), - organic acid composition (1.5% lactic acid, 0.5% acetic acid, less than 0.1% butyric acid).

NUTRITIVE VALUE OF CORN SILAGE DM (%) 30-35 CP (%, on DM basis) 10 NEl (MJ/kg, on DM basis) 6-7 CF (%, on DM basis) 20.

Quantities of Silage Fed to Animal Species Corn silage kg/animal/day Cattle 25-30 Sheep 5 Horse 10-15 Sow 5-6.