Analysis of Association Between the MUC4 g.8227C>G Polymorphism and Production Traits in Italian Heavy Pigs Using a Selective Genotyping Approach

Abstract

In pigs, susceptibility to enterotoxigenic Escherichia coli (ETEC) K88 strains (locus F4bcR) is determined by a dominant allele, with the recessive allele determining resistance. The susceptible allele also appeared to be associated with higher growth rate even with discordant results. A single nucleotide polymorphism (SNP) in exon 7 of the mucin 4 (MUC4) gene (DQ848681:g.8227C>G), shown to be in close linkage disequilibrium with the F4bcR locus, has been used as marker to identify susceptible pigs, substituting invasive villous adhesion tests. We herein analyzed this SNP in Italian local breeds and applied a selective genotyping approach in Italian Large White, Italian Landrace, and Italian Duroc comparing allele frequency distribution in groups of pigs with extreme estimated breeding values (EBV) for average daily gain (ADG) and backfat thickness (BFT) to evaluate if this marker is associated with these traits. Allele G (associated with susceptibility to ETEC) was associated with higher ADG and BFT in Italian Large White (P = 6.66E-04 and P = 0.012, respectively) and higher ADG in Italian Landrace (P = 7.23E-12). This polymorphism was poorly informative in Italian Duroc. Antagonistic associations of the MUC4 g.8227C>G alleles on susceptibility to ETEC and growth performances evidence the complexity of applying marker assisted selection in pig breeding.

Keywords:

• Growth rate
• Italian heavy pigs
• MUC4
• Selective genotyping
• SNP

Acknowledgments

We thank ANAS for providing samples and data and Dr. Emilio Scotti (University of Bologna) for technical assistance. This work was funded by Italian Ministry of Agriculture (MiPAAF INNOVAGEN project) and by University of Bologna (FAGenomicH project).

Notes

^a ILW = Italian Large White; IL = Italian Landrace; ID = Italian Duroc; ADG = average daily gain; BFT = backfat thickness.

^b Extreme divergent tails selected according to the lower (negative) or higher (positive) EBVs.

^c IL/ADG negative tail: 73 females and 27 castrated males; IL/ADG positive tail: 68 females and 32 castrated males; ID/ADG negative tail: 67 females and 33 castrated males; ID/ADG positive tail: 67 females and 33 castrated males.

^a Two generation unrelated pigs of the selective genotyping study using backfat thickness estimated breeding value.

^b Two generation unrelated pigs of the selective genotyping study using average daily gain estimated breeding value.

^a ILW = Italian Large White; IL = Italian Landrace; ID = Italian Duroc; ADG = average daily gain; BFT = backfat thickness.

^b Extreme divergent tails selected according to the lower (negative) or higher (positive) EBVs.

^c After DNA quality control of extracted genomic DNA, a few animals of the selective genotyping panels (Table 1) were excluded from genotyping or genotyping failed.

^d Chi square or two tailed Fisher's exact tests (where appropriate) of significance of allele frequency differences between the two extreme tails of the genotyped pigs. Tests refer to the comparisons between the negative and positive tails adjacent to the P value.

^e Considering all selected pigs for the two tails.

^f Considering only two-generation unrelated pigs for the two tails.

L. Fontanesi and F. Bertolini contributed equally to this work.

Additional information

Notes on contributors

Luca Fontanesi

L. Fontanesi contributed equally to this work.

Francesca Bertolini

F. Bertolini contributed equally to this work.