The possibility of positive selection for both F18(+) Escherichia coli and stress resistant pigs opens new perspectives for pig breeding

F18(+) Escherichia coli infections causing post-weaning diarrhoea and/or oedema disease are a major cause of economic losses in pig industry. To date, no preventive strategy can protect pigs from F18(+) E. coli infections. One of the most attractive approaches to eliminate F18(+) E. coli infections is the selection for pigs that are resistant to F18(+) E. coli infections. However, this strategy was not believed to be favourable because of reports of genetic association with the stress-susceptibility gene in the Swiss Landrace. To investigate this potential association more thoroughly, 131 randomly selected Belgian hybrid pigs were genotyped for both the F18(+) E. coli resistance alleles (FUT1(A)) and the stress-susceptibility alleles (RYR1(T)) and their association was investigated by determining the linkage disequilibrium. This linkage disequilibrium (LD = -0.0149) is close to zero and does not differ significantly from 0 (likelihood ratio test chi(2)(1)=1.123, P = 0.29), demonstrating no association between the FUT1(A) and RYR1(T) alleles. Furthermore, only a small fraction (4.6%) of the Belgian pigs was found to be resistant to F18(+) E. coli infections. Our results suggest that selection for F18(+) E. coli resistant pigs might be an attractive approach to prevent pigs from F18(+) E. coli infections, unlike to what has previously been postulated. (C) 2007 Elsevier B.V. All rights reserved.