QUALITIES OF FEED PELLET.

Feed pelleting can be defined as conversion of finely ground mash feed into dense, free flowing pellets or capsules, in a process that involves steam injection (moisture and heat) and mechanical pressure. There are several advantages for feeding broilers pelleted rather than mash feed. The main advantage is the improved bird performance (improved feed intake, weight gain and feed conversion). Birds fed pelleted diets spend less time and need lower maintenance energy requirements during eating and digestion in comparison to those fed mash feed. The other benefits of feeding pelleted diets include increase feed density, decrease feed dustiness, wastage and selection, better mechanical handling of feed on the feed lines, and destruction of feed-borne pathogens. Therefore, the full genetic potentials of modern broiler strains cannot be achieved without pelleted feed. In order to achieve these multi-benefits, the pellet durability should be of a standard quality (not contain too much fines), otherwise, the bird’s performance will be adversely affected. High quality pellets can be defined as pellets that can withstand repeated handling as can occur during bagging, transportation, storage, and moving on feed lines without excessive breakage or generation of fine particles. Pellet quality is usually expressed as the pellet durability index (PDI), and measured by using a tumbling can device, in which the pellet sample to be tested is first sieved to remove fines, then tumbled in the tumbling can device for a defined period of time. The tumbled sample is then sieved to remove fines, and the amount of intact pellets is determined. Factors affecting pellet quality Several factors have an effect on the quality of the pellets. First of all the feed formulation (raw materials and additives used). Some feed ingredients have a good impact on pellet quality, while others could adversely affect the quality. Unfortunately, corn-soy diets are not the ideal diets to achieve the desired pellet quality. Dietary inclusion of wheat grain or wheat by products (wheat midds, wheat gluten) can increase pellet durability, because of the high protein (gluten) and hemi-cellulose content of wheat in comparison to corn or corn co-products. Similarly inclusion of oat as a partial substitute of corn can increase pellet quality. We can rank feed grains according to their positive impacts on pellet quality from best to worst as followings:oat,wheat,barley,corn and sorghum. It was previously known that starch and its gelatinisation is the most important factor for achieving the desired pellet quality. However, recent reports indicated that the positive impact of protein on pellet quality is much more important than that of starch. Dietary inclusion of oil has an adverse effect on pellet quality. This is attributed to the coating effect of oil to the feed particles which prevent their penetration by the steam, also oil reduces the friction generated between die and feed particles with subsequent decrease in the starch gelatinisation rate. Inclusion of binding agents (e.g. water (simplest binder), lignin sulphonate, hemicelluloses extract, gelatin, etc.) and/or surfactants can increase pellet quality. Pellet quality can be influenced by several factors, including the ingredients, diet formulation and processing. A good rule of thumb is the pellet quality factor (PQF), that each feed ingredient has. The PQF has a score from 0 to 10, where 0 predicts poor pellet quality and 10 good pellet quality. From experience we know that starch and its gelatinisation is the most important factor for achieving the desired pellet quality. However, recent reports indicated that the positive impact of protein on pellet quality is much more important than that of starch.