Harvest & post-harvest Physiology and Preservation

Forage Harvest Losses  Fresh Forage  Living, Breathing, Making & Using Energy  Taking up and Losing Water  70 ~ 90% Water (10 ~ 30 % DM)  Bacteria and Fungus Contamination

Forage Harvest Losses – start in the field  What happens after cutting  Plants continue to ‘live’  Using stored energy  Losing water through pores and epidermis  Miner amounts of proteins are converted to Non-protein N (0.5% / hour)

Forage Harvest Losses – start in the field  At about 50 ~ 60 % moisture  Pores close at about 70 %, water loss rate slows down  Some part still ‘alive’ using sugars (until about 30~40% moisture) (until about 30~40% moisture)  About 1~4% of DM is lost as non- structural carbohydrate, up to 16% during extended warm, humid condition  

Forage Harvest Losses – start in the field  Below 40% moisture(26~40%)  Plant is dead (no longer respiring)  Soluble sugars can leach from all damaged and dead cells  Bacteria, fungi, yeasts etc using sugars, generating heat

Forage Harvest Losses – start in the field  Below 25% moisture  Most bacteria are ‘inactive’  Fungi & yeasts are still active, using sugars, generating heat  Below 10% moisture  Bacteria, fungi, yeasts are inactive  Hay is stable until moisture content increases

Post-Harvest Physiology  Drying process  Factors which influence drying and the quality of forage during drying  Metabolic  Mechanical  Weathering

Post-Harvest Physiology  Drying rate  Methods for increasing drying rate  Adequate periods without rainfall (probability of rain-free period) (probability of rain-free period)  Mechanical Conditioning : crush, bend  Chemical conditioning : potassium carbonate, Organic Acids  Raking, Tedding

Preservation and Storage  Hay and Silage storage system  Important processes in curing or fermentation  Preservative and additives