Transcript Harvest & post-harvest Physiology and Preservation

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)
< bacteria and fungi are still around >
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)
 About 1~4% of DM is lost as nonstructural carbohydrate, up to 16% during
extended warm, humid condition
 < bacteria and fungi still around, using energy,
generating heat >
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)
 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