Pelletising for Africa

In Africa the most common large-scale commercial farms are broiler chicken and egg producers, and this category of food producer is also the largest user of pelletising machines.

Pelletising improves chicken production through better feed conversion and growth rates. One research project has indicated that chickens spent 14.3% of their time in a 12 hour day feeding on loose feeds, versus only 4.7% with pelletised feeds. Research from various sources has shown an improvement in feed conversion of 12%.
Beyond chicken farms, there are generally relatively few large-scale commercial farms in Africa, and therefore most pelletising machines are bought on a co-operative basis as add-ons for grain mills.
There are virtually no human food products which are pelletised, although pelletisation is a good way to preserve food.
Mario van Niekerk, CEO of ABC Africa Group, a South African supplier of pelletisers, says in Africa pelletisers are mostly used for production of feeds, but also for transporting bulk products, such as bran, more efficiently. He believes that there is potential for extruded fibre pellet products for human consumption as fibre can form part of any foodstuff. In aquaculture pressed sinking pellets for bottom feeders are pelleted, while f loating pellets are extruded.
But pelletising of animal feeds of all kinds should be immediately more popular because of the efficiencies that it offers to farmers and feed producers of all kinds, and superior feed conversion ratios.
Francesco van Wyk, engineer for Drotsky, a leading manufacturer of small hammer mills in South Africa, says that a trend towards processing of feed into pellets is strong in South Africa.
In South Africa, he says, commercial farmers generally no longer want to buy feed from feed companies – they are increasingly producing their own feed, the most efficient form of which is pellets.
Currently, however, he says, the overwhelming majority of Drotsky’s sales in the rest of Africa are of simple hammer mills, because this is the first step in producing human and animal feeds. The second step is a mixer, and finally a pelletiser.
Van Wyk says that while the case for installing a pelletiser is strong, considerable capital is needed because a pelletiser must be part of a complete feed production line.
The most basic feed production line offered by Drotsky, which is labour-intensive, consists of a small hammer mill, a small auger, a mixer and a pelletiser. Such a line processing 250kg/hour would cost about $13,000 (ex factory). A more mechanised line producing 1t/hour, which would include a steam unit to condition the pellets, and a cooling unit for post-production, would cost about $100,000.
In South Africa, he says, farmers are increasingly using pelletisation to save on their ever-rising feed bills. Chicken farmers, feedlot owners and other farmers in the rest of Africa will undoubtedly eventually do the same, he says.
Johan Eksteen, MD of Agricon, which has been supplying pelletisers since 1993, says the savings are not only based on the elimination of the middleman (whose prices are often about $100/ton on pelletised products, compared to the raw materials), but also because the farmer has control over his/her formulations. In this way the farmer can add value to poorer quality feeds, reducing cost without compromising overall quality. The only disadvantage of pelletising is that it raises the cost of the feed due to infrastructure and labour costs.
Van Niekerk says pellets for own use seldom have steam injected. Harder pellets required for transport and handling are normally steam-injected. Steam injection also increases capacity – on poultry feed, for instance, from 40-45kg per kW of power to 80kg per kW. Van Niekerk says that while most pelletising units require electricity supply (normally 3-phase), his company can supply units powered by diesel.

Weighing up feed/ration costs
Depending on the facility, the milling costs about $5-$14/ton, and pelleting about $9-$12/ton, according to Eksteen. He says on a medium-sized farming operation the wastage of loose feeds can be 200kg/day or more (depending on feed volumes). With a ration cost of $250/ton, wastage of $50/ton could occur. Over 365 days, wastage would therefore cost the farmer $18,250.
With lower feed conversion rates, a further loss would be made over the year.
So, although the economics of feed processing is little-considered, it can actually be the most influential factor affecting feed costs.
Eksteen recommends that farmers and nutritionists feed animals on the basis of available energy and protein, or amino acid concentrate, coupled with optimal vitamin and mineral supplements.
“The modern farmer should determine the exact biological values of feeds on the basis of the needs of different species,” he states. “Farmers should not try and research these formulations themselves because formulations are offered free as a service by many feed distributors. Although many of these feed distributors produce their own pellet products, they are also keen to sell vital ingredients (for instance, protein concentrates and molasses) to other pelletisers.
“The days are gone where animals’ bellies were just filled with no specific purpose. Farmers need to get value for their money in animal production. Due to the production cost squeeze, feed is the greatest cost factor in animal production. Even in the case of sheep farming, where more roughage is fed, feed costs can still account for up to 55% of total sheep production cost. For poultry, the corresponding feed costs figure will be about 70% of total production costs.”
Eksteen says because pelletising costs about $9/ton on an Agricon machine, the premium placed on commercially-bought pellets over loose feed – perhaps $100 – is excessive.

Buying and usage advice
But Eksteen warns that not all pelletisers are the same. He says it is very important to control the feed rate of a pelletiser – otherwise the machine will constantly over- or underperform, resulting in blockages or poor production capacity. The machine works under huge pressure, with considerable vibration, so its body must be durable, strong and well made.
It takes feeds 20 seconds to go through the machine; air-dry feeds (about 10-12% moisture) need a little more moisture (13-15%) to activate the pellet binding process. Binding happens under extreme pressure as the pellets are pressed through the holes at temperatures of 60-90°C.
The heat is caused by pressure and friction produced by the machine. Poorly designed machines will not reach sufficiently high temperatures, resulting in the need for binding agents like molasses.
The pellets are then cooled by various mechanical and non-mechanical methods to a final moisture level of 12-13%.
Several misconceptions prevail about pelletising because of the historical use of pelletisers. The greatest evil, Eksteen says, is the inclusion of a high percentage of molasses to bind the pellets. “The heat will caramelise the sugars, resulting in the holes becoming sticky and clogged. Water should therefore be the only activator.
Also, the pelletising machine’s compression ratio must be adjusted for different types of feed.”
Eksteen adds that many people struggle with pelletising because they do not realise that the same die ring cannot be used for different feeds as they may differ materially in their adhesive and cohesive properties.
Once this is taken into account, though, animal feeds are fairly standard he says. “But keep in mind that you need to stick to the basic principles of nutrition, meaning good quality proteins and starches.”
Pelletisation causes gelatinisation of starches which makes the feed more digestible. The greatest advantage of pelleting is in grains. The advantage is that it increases the enzymatic digestibility of starches. It is important that gelatinisation is not only on the outside of the pellet, but throughout the pill. Shiny pellet appearances are an indication of poor gelatinisation because of incorrect pressure ratios.
Acceptable pellets are fairly long and hard, with a dull surface colour and little dust in between. The pellets should also not fall apart with handling.
Agricon, Johan Eksteen: Tel +27 71 877 3324;
Drotsky: Tel +27 11 864- 1601;
ABC Africa Group: Tel +27 12 803 0036;
Agrifeed Systems: Tel +27 83 260 7067;
Joesten International: Tel +27 11 915 3269;
Rumax/BJP Supplies: Tel +27 23 342 6070;

The benefits of pelletising
•    Improved animal performance, with higher energy intake while animals spend less energy on grazing.
•    Pelleted feed promotes animal growth due to better feed conversion rates – in other words, better utilisation of the nutrient value of the feed.
•    The heat generated in the pelletising process results in less energy needed for breakdown of protein and starches in the rumen of ruminants, thereby increasing amino acid availability and animal performance.
•    Pelleting reduces wastage by up to 30% versus selective eating in the case of loose feeds.
•    There is no dropping out or separation of certain ingredients – pelletised feeds are bound as uniform-quality feed so no selection of tastier raw materials can be done by the animal.
•    Pelletising eliminates dust and thereby increases the taste and palatability of the feed. Also, unlike with loose feed, there is no wind loss.
•    Destruction of pathogens during processing results in healthier feeds. Pellets are especially formulated for easy storage and will not easily spoil, as is the case with loose feeds. Not even temperature differences will affect the taste, appearance and structure of pellets.
•    Rations are less bulky, reducing storage space, transportation and handling requirements.