Coli bacteria attach themselves to the intestinal wall of the piglets. They secrete their toxins into the bloodstream of the animal, causing the piglets to fall ill.
The various coli bacteria attach themselves in different ways. In technical language, this is referred to as “fimbriae type”. Coli bacteria of fimbriae type 18 (F18) are one of the main causes of oedema disease or deduction.
In the 1990s, the Swiss University for Science and Technology Zurich discovered a natural mutation in the pig genome. In the case of homozygous animals (CF18 = A/A), the intestinal wall is slightly different to that of susceptible pigs. As a result, E. coli F18 bacteria can no longer attach themselves to the intestinal wall of resistant piglets.
With DNA typing, direct checks can be carried out in the genes of the piglet to ascertain whether it is resistant to E. coli F18 bacteria. In the nucleus breeding farms, the results of these genotypings are included in subsequent selection decisions and breeding measures are taken specifically to counter the susceptible allele.
All active AI boars in the Swiss Large White line have long been homozygous resistant; this is now also true of the entire sow population.
A systematic early genotyping of piglets also takes place in the Landrace breed. As a result, most boars and about 50% of the gilts are now homozygous resistant.
Moreover, breeding and selection in the sirelines has also focused systematically on homozygous E. coli F18 resistance for several years; and recently on E. coli F4 resistance. Today, only homozygous E. coli F18 resistant PREMO® boars (A/A) and increasingly homozygous E. coli F4 resistant boars are purchased for AI use. Some homozygous resistant boars also feature in the SUISAG Duroc and SUISAG Piétrain breeds.
Selection based on E. coli F4 resistance commenced in the PREMO®, Duroc and Piétrain breeds in 2018.