Knowledge of particular materials properties lets machine operator predict the effect of density, pressure and warmth on the formula so that operator could determine the best conditions of machine work to pellet feed.
Feed and constituent's properties are determined by following factors:
The quality of pelleted feed changes when the characteristics of raw materials changes, due to this and constant pellets quality, properties and quality of raw materials should be controlled.
In case of big differences look for additional methods of compensation.
Protein and weight
The efficiency of machine and determined formula pellets quality can predominantly be predicted on protein content and weight.
Ingredients with high protein content become plastic (warmth effected) and in consequence high quality of pellets is achieved.
High density ingredients or feeds make possible to achieve high efficiency. When an ingredient or feed contain lots of natural protein and have high density we can expect high efficiency and high quality of pellets; but when there is low protein content and high density we can expect high efficiency but worse quality. Pelleted maize is an example.
Ingredients or feed with high protein content and low density results good pellets quality, but lower efficiency.
For example: crushed ears of maize with wheat grains, cotton seed shells, wheat gluten meal.
Weight of raw materials is an important factor determining the efficiency of pelleting press.
Light material, with high fibre content results the less production (efficiency)
Milling / Crushing / Grinding
Small particles
Fine milling to small particles we achieve higher density and following benefits:
- better quality
- increase of production efficiency
- increase of volume density
- higher HP efficiency
- longer matrix life
Particularly important is that steam penetrates small particles, makes them softer and more plastic but is not able to go into large ones.
Besides large particles can cause cracks in pellets. It is recommended to use the sieves with mesh diameter smaller then 3 mm in hammer mills.
By means of finely milling the efficiency of pelleting press increases and less power is used to pelleting. It's worth to mention that milling, reducing wipe properties of material, results increase of matrixes life.
Fiber
Fiber decreases productive efficiency of pelleting press, because it's difficult to compress fiber into pellet. However at the same time, thanks to natural bindings appeared in fiber high quality pellets is obtained.
Fat
"Fat content" means both natural and supplemented fat concentration. Both natural and supplemented fat contribute to increase of productive efficiency.
However excessive fat concentration (usually not more then 2%) can show negative effect on pellet's quality. Supplemented fat can be derived from animal and vegetable.
Pelletometry may be thick, thin, medium.
Finely milled raw materials have larger area of steam humidity absorption. It results better “lubricatation” of material and higher production efficiency, because of greater number of small particles being exposed on steam activity.
Density may be increased by finely and midly milled materials mixing. Negligent material crushing causes cracks in pellets.
Starch
It's difficult to product strong pellets from starch rich ingredients.
Starch glue property become active in high temperature and high humidity. Gelatinized material functions as lepiszcza and helps to achieve expected quality of pellets.
Important: if for any reason natural starch contained in feed is gelatinized we should expect worse quality of pellets.
Example is cereal grain drying in high temperatures, which causes pre-gelatinisation.
Moisture (humidity)
Sometimes it's necessary to add some moisture before pelleting process for good quality of product. Many of actually used ingredients are very dry and besides added moisture we should add steam, especially when earlier moisture was absorbed before mixture get into conditioner.
Binders
When expected quality of pellets can't be achieved nor by steam conditioning or using proper matrix we can use bonds.
Two of usually used are: bentonit, lignin sulfate. Using of lignin sulfate is expensive so should be the last solution.
Organic and inorganic acids used by feed industry.
Acids are usually used in feed industry as antibacterial, anti-mould or acidifying factors.
Phosphoric acid: inorganic, liquid in natural, no sour smell, corrosive
Acetic acid: organic, liquid in natural, sour smell, corrosive
Formic acid: organic, liquid in natural, sour smell, corrosive
Propionic acid: organic, liquid in natural, sour smell, corrosive
Lactic acid: organic, liquid in natural, nice smell, corrosive
Citric acid: organic, crystalic or powdered in natural, nonintensive smell, less corrosive
Technical notice:
Usually organic and inorganic acids are not used by feed industry as pure forms because they are corrosive. To eliminate the problem there are available liquid or solid-dry forms properly buffered (buffered saline) to weaken corrosive property.
Mentioned recombined forms are more expensive then pure acids.
There are acid additives less expensive but more corrosive.
It's recommended to use products from checked, trustworthy firms who offer good quality, non-corrosive acid additives.
Feed additives are mixed with mixture to increase the quality, disease prevention or feed conservation; short list as following:
Anthelmintic
Medicine used to prevention from parasite infections.
Antibiotics
A kind of medicine synthesized by alive organisms (mould, fungi, bacteria, plants) having antiseptically properties, like: penicillin, streptomycin etc.
Antioxidants
Added to feed for reduction of oxidation and fat go off.
Carotene
Pro-vitamin A, usually provided with chlorophyll, but synthetic form can also be supplemented to feed.
Regulators
Substances added to soluble for adapt to pH changes. Used in ruminants nutrition for optimal pH : 6,2-6,5, which lets to digest feed and synthesize microbial protein: rumen microbial: bicarbonate, bentotin, magnesium monoxide.
Choline
Water soluble vitamin associated with fat metabolism and transport. Common poultry and hogs feed additive. Most ruminants synthesize enough of choline but choline can be supplemented in cows at the first stadium of lactation diet.
Coccidiostatics (anticoccidian)
Medicine used in coccidiosis treatment. Coccidia is intestinal protozoa occuring in cattle and poultry intestines.resulting in diarrhoea and big wastage.