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

CHEMICAL CHANGES

Plant & microbial enzymes: 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. Plant enzymes proteolyse the protein resulting in formation of free amino acids that could be lost due to leaching.	Sugars (O) CO2 + H2O Protein to Amino acids
Oxidation: During 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.	Reduction in carotene. Vitamin D high.
Leaching: Leaching causes loss of soluble minerals, sugars and nitrogenous constituents in addition to facilitating mould growth.	Loss of minerals, sugar & Nitrogen. Mould growth.
Microbial action: Microbes flourish during drying for prolonged period under bad weather leading to moldy hay that are unpalatable & harmful to farm animals & man. Such hay may cause allergic diseases affecting man known as hay fever or farmer's lung.	Drying for prolonged period lead to hay fever.
Plant Species: Legume hays are rich in protein & minerals than grass hay. Non-legume hay has more carbohydrate but less palatable.	Legumes are rich in protein & minerals.
Stage of growth/cutting: The nutritive value of hay depends on the stage of growth of the crop at the time of cutting. Harvesting matured crop results in hay with lower digestibility, lower net energy value and lower palatability but with larger yield. Harvesting immature crop results in hay with higher digestibility, higher net energy value and higher palatability but with lower yield. Hence crop should be harvested when they are about to mature to compromise yield and quality. Two third flowering stage is the optimum period for harvesting to make good quality hay.	Harvest at 2/3rd flowering to make good quality hay.
Mechanical damage: Since leaves lose moisture more quickly than the stems, they become brittle and easily crushed by handling. Handling hay during early morning minimise loss of leaves. Flattening of herbage facilitates uniform drying and thereby reduces shattering.	Handling hay during early morning minimize loss of leaves.