Pelleting can be generally defined as an extrusion type thermoplastic molding operation in which the finely reduced particles of the feed ration are formed into a compact, easily handled, pellet. It is thermoplastic in nature because the proteins and sugars of most feed ingredients become plastic when heated and diluted with moisture. The molding portion of the operation occurs when this heated, moistened feed is forced into a die, where it is molded into shape and held together for a short time. It then exits as an extruded product. Pressure for both molding and extrusion comes from pellet mill rolls which force the feed through the holes.
There are many financial advantages to a pelleted feed product. These advantages are:
1. The combination of moisture, heat and pressure acting on natural starches in feed ingredients produces a degree of geletinization. This enhances the binding qualities of the starch-containing ingredients resulting in better pellet quality. This improved feed conversion advantage is particularly evident in the Poultry Industry.
2. Pelleted feed prevents selective feeding on favored ingredients in a formulation. Since all ingredients have been molded together, the animal must eat a balanced formulation, minimizing waste and improving feed conversion.
3. Pelleting prevents segregation of ingredients in handling or transit. With medicated feeds and concentrates, this avoids disproportionate concentrations of micro-ingredients and resultant ill effects.
4. Pelleting has been shown to reduce molds in feed, again increasing feed conversion.
5. Pelleting increases bulk density, particularly on alfalfa, beet pulp, gluten feeds and other such fibrous products. On alfalfa pelleting, for instance, one can increase the bulk density by a ratio of approximately 2 to 1. Densification is, of course, dependent upon the characteristics of the product being pelleted. In bagasse, a by-product of the sugar extraction process, we see densification from 8 pounds per cubic foot to 32 pounds per cubic foot. The advantages in storage and shipping are self-evident: higher pay loads and reduced bin requirements.
