ANN 111: Principles of Animal Nutrition and Feed Technology (2+1)

CHANGES DURING STORAGE

Dark brown colour observed in over heated hay stored at higher moisture level during stacking is due to oxidative degradation of sugars combining with amino acids or proteins. Plant respiration ceases at about 40oC, but thermophillic bacteria continue to be active until 72oC and therefore oxidative degradation continues in hay containing thermophilic bacteria. The heat tends to accumulate in hay stored in bulk and eventually combustion may occur.

Thermophillic bacteria continue oxidation in hay with higher moisture content. Heat generated by oxidation leads to combustion.

Losses in nutritive value of hay are due to:

• Losses due to late cutting.
• Losses of leaves by shattering.
• Losses due fermentation.
• Losses due to leaching.

Biochemical changes during and storage of hay: Carbohydrate: Plant continues to respire even after harvest and during respiration, the sugars are oxidised to CO2 and H2O leading to increase in concentration of cell wall constituents like cellulose and lignin. Organic acids concentration decreases during wilting. Nitrogenous constituents:  Plant enzymes proteolyse the protein resulting in formation of free amino acids. Cynogenic glycosides in forages lose their toxicity during drying due to denaturation of enzymes. Vitamins: During Sun drying oxidation occurs leading to reduction in the carotene concentration and that is why sun drying should be stopped when greenery starts fading. But sun drying enhances the vitamin D content in the hay due to irradiation of ergosterol present in green plant.

Sugars   (O)  CO2 + H2O Protein         Amino acids Reduction in carotene Vitamin D higher