These are the processes by which the particle size of cereals, oil cakes and roughages including green fodders and crop residues is reduced employing various types of power driven or manually operated machines. Hammer mill or attrition mill is used for grinding while a sharp edged gandasa or an indigenously developed chaff cutter, known as toka, fitted with two blades are used for chopping. Chaff cutter can be operated manually or with the help of electric motor. In case of manual operation, minimum two persons are required, one to rotate the vertical wheel attached to blades and the other to drive the fodder to be chopped to the machine. Fodder, kept in trough is propelled horizontally through feed rollers into the blades, which move by the rotation of wheel. The fodders can be chopped uniformly into fine (0.5 cm) or coarse (1-2 cm) particles. In case of power operated toka one person is sufficient to handle it. Power consumption inchopping depends upon physical characteristics of materials such as moisture, thickness and level of fibre and its strength. Normally, power consumption is more in case of crop residues such as paddy straw and jower kadbi than for green fodders. Sharpness of the blades and proper lubrication of machine should be maintained for the optimal efficiency of toka machine.
Chopping of roughages size has the following advantages:• Facilitates feeding and avoids wastage• Facilitates mixing with other ingredients of ration and checks selective feeding• Facilitates handling due to increased bulk density• Improves digestion due to exposure of relatively larger surface area of roughages for microbial digestion
Chopping improves voluntary dry matter intake, but does not affect the nutrient digestibility, which is generally attributed partly to the increased bulk density and partly due to less time required to reduce the particle size of the ingested material size suitable for digestion by rumen microbes. However, enhanced feed intake without selection of most nutritious part and reduced wastage of fodders/ straws following their chopping makes it economical. Sugarcane tops (CP 5-6% and TDN 50-55% DM basis), an important source of roughage in sugarcane producing areas, is utilized for animal feeding after its chopping and mixing with other roughages and feeds in the form of sani as it dilutes the effect of coarse surface of leaves, which restricts its intake.