Research has shown that technologies for pelleting feed differ in their effect on dietary performance. In Europe, practicing swine nutritionists designed a range of nursery pig diets based on specific processing technology with the goal to optimize conditions for digestion in the stomach and small intestine and for fermentation in the lower gut.

Most manufactured rations for baby pigs are processed through a conventional steam-conditioned, compression pelleting process. These typically high-protein, high-fat products may be in the form of small diameter pellets or crumbles. Conventional compression pelleting technology usually applies even to hygienic nursery feeds in which the mash may be pasteurized during steam conditioning under pressure in an expander or through a longer retention time at atmospheric pressure. Some creep' products are manufactured in the same way, designed for the feeding piglets in the farrowing crate during the last several days of nursing. During the first few such feedings, the pelleted product may even be moistened by hand, making it more aromatic and softer in order to increase intake.

These creative adjustments of conventional pelleted feeds for young pigs have illustrated the critical need to provide a smooth transition from sow's milk to dry feed in order to reduce ‘weaning lag' and optimize the pig's growth potential. Increasingly, however, feed manufacturers are looking closely at the form of the feed for pre-starter and starter feeds, including the processing technology used to produce such products. Their attention to the feed form accounts for the increasing use of ‘pellet-cooker' feed processing, which contrasts significantly with conventional steam-conditioned pelleting for the manufacture of feeds for young pigs (see box).

European approach

The use of pellet-cooker technology for pig starter feeds got its start in western Europe, where there is intense competition among commercial swine nutrition products. Leading the way was the Cehave Landbouwbelang Group (www.cehave.nl), a leading cooperative organization in the agri-food business based in the Netherlands. Cehave has about 11,000 members, including many pig producers, and operates feed plants in the Netherlands, Belgium, and Poland.

The Cehave plants produce a wide range of feed products, totaling more than 2.5 million tons of feed per year. The co-op's Cehave International division (www.vitamex.com) also focuses on complete feeds, concentrates, and premixes. The organization's Nutricontrol division is comprised of feed and food safety and quality control laboratories serving Cehave and other feed and food makers under contract. Likewise, Cehave's CCL division focuses on feed and food research, including feed studies for pigs, poultry, and beef cattle at the division's Laverdonk research farm in the Netherlands.

At CCL Research (www.ccl.nl), a multi-disciplinary team, led by research director Ruud Tijssens, began in 1998 to design diets around the pellet-cooker process. The Dutch feed scientists did not simply take a formula from the pellet line and start making it on the new equipment. For their pig starter product, they sought particular characteristics that would derive from the product's processing.

Stomach condition

Particularly, the pellet-cooker's very short-term, high-temperature processing was supposed to improve conditions in the stomach, favoring enzyme activity and digestion, and reducing risk of stomach disease. Stomach condition scores of pigs fed diets processed by pellet-cooker or conventional pelleting equipment bore out this approach (see figure).

Other desired effects were healthier fermentation in the lower intestinal tract, which could be influenced by the degree of starch modification in the grain component. Also, there could be improved feed intake, which could result from a number of factors, including greater attraction and palatability of a ‘cooked' product. The quick cooking effect also offered greater potential to use a variety of wet co-product ingredients, including bulk yeast and molasses products.

Ultimately, the CCL researchers found the pellet-cooker-designed product offered faster growth in young pigs, roughly a 25-gram advantage through the starter phase, as well as better feed conversion (up to 6% better feed-to-gain). The pellet-cooker-fed pigs also had nearly 1% less mortality and the researchers remarked on more uniform growth among groups of pigs as well as healthier appearance of the pigs, particularly their color.

An important characteristic of the pellet-cooker pig feeds tested at CCL was their lower bulk density in the range of 520 g/l versus 650 g/l for conventionally pelleted feeds. The Dutch scientists suggested that this characteristic promoted faster feed hydration in the pig stomach, up to six times faster than for the denser pelleted feed. As a result, the pigs consumed less water, resulting in more solid manure. The pig housing units at Laverdonk were drier, manure was easier to remove, and pig houses were quicker to clean. So, the Dutch researchers reasoned, although the typical feed delivery truck may not be able to haul as much product by weight as for a conventional pelleted feed, the pellet-cooker-processed feed was more efficient in feeding and there was less waste to clean up. As a result, efficiencies were higher overall.

Cost consideration

In the last half of 2003, Cehave introduced the Air Line range of pig feed products, which were manufactured by pellet-cooker. These innovative products were the result of extensive process-formulation research involving some 15,000 pigs over several years.

The cost considerations related to this range of products, as explained by Cehave, were particularly interesting. For example:

  • For nursery feeds, pellet-cooker products were priced $9.00 per ton more than standard pelleted nursery feeds;
  • For the next stage of starter feeds, pellet-cooker products were priced $4.20 per ton more;
  • Despite these higher feed costs, the pig feed customers' profits were $3.40 per pig more for those fed the pellet-cooker products compared to a standard pelleted feed.

Today, swine starter feeds can benefit from 'rethinking,' going beyond consideration only of ingredients in developing innovative products. For example, although the pellet-cooking process itself may be more energy intensive than conventional steam-conditioned pelleting, there are overriding energy-related efficiencies. The pellet-cooker product offers greater feed efficiency, which means less to feed as well as less manure to handle. In this time of higher energy costs, such process-related savings can translate to overall savings to pig feed customers over conventional pellets.