E. coliresistance: The end of post-cycle therapy diarrhea?!
Post-weaning diarrhea and edema disease are swine diseases that can cause significant economic losses. Both diseases are triggered by infections with pathogenic E. coli bacteria. Crucial to life-threatening disease progression are so-called adhesion factors (fimbriae). These cell appendages bind to receptors in the small intestinal mucosa; only after binding to the receptors does the rapid division of the E. coli bacteria begin, leading to lasting damage to the mucosa. Not every animal develops these crucial receptors; their presence is genetically determined.
Project ZAC: Breeding for E. coliresistance
One approach to reducing diseases caused by E. coli bacteria of a specific fimbrial type (F18) is the breeding of homozygous (A/A) pigs. This genetic variant does not produce receptors for pathogenic E. coli bacteria; fimbriae of these bacteria cannot attach to the intestinal wall, and the pigs are therefore resistant. The aim of the ZAC project (2022–2024) was to evaluate the effectiveness of breeding for resistance with regard to the occurrence of post-weaning diarrhea. As a first step, the genetic status of all sows in the experimental herd of the Institute for Organic Agriculture was determined, and homozygous sows were bred with homozygous boars to obtain homozygous offspring. In the next step, a total of 804 piglets were examined for their susceptibility to post-weaning diarrhea after a six-week suckling period. For this purpose, the fecal score was collected and documented over four consecutive days. A scale from 0 to 2 was used for the examination: formed feces = 0; Stools mushy = 1; stools liquid = 2 (see graphic).
Grade 0 Grade 1 Grade 2
Results
Statistical analysis revealed no significant differences in the incidence of post-weaning diarrhea between homozygous and heterozygous piglets. The incidence of diarrhea decreased significantly over time (day 2, day 3, day 4), which can be attributed to the treatment of affected piglets. In contrast to homozygous piglets, the frequency of fecal score 2 decreased with increasing lactation time. This was reflected in the less frequent assignment of score 2 as lactation length increased. Furthermore, a seasonal effect became apparent during data analysis. The proportion of fecal score 2 in the observations was highest in the first quarter and lowest in the third quarter, with values in between for the second and fourth quarters. This effect will be examined more closely in follow-up studies.
Conclusion
Post-weaning diarrhea is a multifactorial problem. While breeding or keeping resistant animals can offer a chance of relief on farms with infection problems based on this specific pathogen (E. coli F18), eliminating one pathogen does not provide a 100% solution in the fight against post-weaning diarrhea.
