For some time now, more and more have turned away worldwide, particularly in Germany, from the hitherto customary fine grinding of pig and poultry feed. For a time, fine grinding was seen as key to achieve high feed conversion rates and good pellet quality with low fines. But today, it is recognised more and more that the vulnerability of our livestock is growing with the genetic progress and that finely ground feed can cause major health problems and reductions in performance. Recent research on pigs has proven that too many fine particles in the feed necessarily cause stomach ulcers, so that the majority of the animals for slaughter is already severely damaged (Nielsen 1998; Kamphues 2007; Große Liesner 2008). In addition, Kamphues et al. (2007) underline the importance of coarse grinding for the suppression of salmonella in pigs. Betscher et al. (2010) refer to the pH-grading of coarse feed structures in the stomach of pigs and poultry, which is not only immunologically important, but also a prerequisite for a high activity of the protein digestive enzyme pepsin.
Today’s high-performance broilers respond to very fine feed structures with changed development of the gastro-intestinal tract: Glandular stomach and pancreas are enlarged and the gizzard is underdeveloped, resulting in health problems and in a reduced performance. Especially under extreme climatic conditions at higher altitudes, which promote the development of abdominal dropsy (ascites), the coarsely ground structure is of particular importance for a good health and high performance of the animals (Taylor and Jones 2004). Various studies have shown that higher contents of coarsely crushed cereals exercise a healthy effect on broilers and that feed conversion and weight gain were not reduced by coarse feed components, but in fact increased (Trevidy 2005). In the latest feeding tests, both structurally ground and expanded broiler feed showed a better protein utilization and a higher lysine effectiveness than finely ground or not expanded feed (Wecke et al. 2011).
The KAHL Crown Expander - a Way out of the Feed Structure Dilemma