Harvest & post-harvest Physiology and Preservation

1. Harvest & post-harvest Physiology and Preservation

2. 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

3. 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 >

4. 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 non-structural carbohydrate, up to 16% during extended warm, humid condition • < bacteria and fungi still around, using energy, generating heat >

5. 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

6. 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

7. Post-Harvest Physiology • Drying process • Factors which influence drying and the quality of forage during drying • Metabolic • Mechanical • Weathering

8. 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

9. Preservation and Storage • Hay and Silage storage system • Important processes in curing or fermentation • Preservative and additives