The effect of adipocyte and heart fatty acid-binding protein genes on intramuscular fat and backfat content in Meishan crossbred pigs

Effects of genetic variation in porcine adipocyte and heart fatty acid-bind ing protein genes, A-FABP and H-FABP, respectively, on intramuscular fat (I MF) content and backfat thickness (BFT) were examined in F-2 crossbreds Of Meishan and Western pigs. The involvement of each FABP gene in IMF accretio n was studied to confirm previous results for Duroc Digs. The F-2 crossbred pigs were genotyped for various markers including microsatellite sequences situated within both FABP genes. Linkage analysis assigned the A-FABP and H-FABP genes to marker intervals S0001-S0217 (20 cM) on SSC4 and Sw316-S000 3 (16.6 cM) on SSC6, respectively, refining previous chromosomal assignment s. Next, the role of both chromosome regions/genes on genetic variation in IMF content and BFT was studied by 1) screening SSC4 and SSC6 for QTL affec ting both traits by performing a line-cross analysis and 2) estimation of t he effect of individual A-FABP and H-FABP alleles on both traits. In the fi rst analysis, suggestive and chromosome-wise significant evidence for a QTL affecting IMF was detected on SSC6. The H-FABP gene is a candidate gene fo r this effect because it resides within the large region containing this pu tative QTL. The second analysis showed a considerable but nonsignificant ef fect of H-FABP microsatellite alleles on IMF content. Suggestive evidence f or a QTL affecting BFT was found on SSC6, but H-FABP was excluded as a cand idate gene. In conclusion, present and previous results support involvement of H-FABP gene polymorphisms in IMF accretion independently from BFT in pi gs. Therefore, implementation of these polymorphisms in marker-assisted sel ection to control IMF content independently from BFT may be considered. In contrast to previous findings for Duroc pigs, no evidence was found for an effect of the A-FABP gene on IMF or BFT in this population.