Association of genetic variants for FABP3 gene with back fat thickness and intramuscular fat content in pig

The swine fatty acid binding protein gene (FABP3) has been screened with 4 primer sets for 270 purebred Yorkshire pigs from National Institute of Animal Science. The selection of primers was based on the swine cDNA sequence (AJ416019), and primer sets (FABP3-2 and FABP3-3) amplified target segments in real time PCR to analyze expression levels at growth stages, producing 235 and 224 bp of fragments, respectively. Relative expression of the swine FABP3 gene for back and intramuscular fat was continuously increased from day 0 to 150, and decreased at day 210, showing the highest expression levels at day 150 compared with day 0. The results may be caused by requirements of high physiological activities with more gene expressions for growth around day 150. Nucleotide variations were observed at nucleotide positions 80 (A/G), 167 (A/G), 260 (A/G), 295 (A/G), 394 (T/C), and 440 (A/G), showing substitutions of amino acids at positions 80 (S to G), 167 (T to A), and 260 (S to G). FABP3 genotypes at positioned nt167 have been associated with carcass back fat thickness (BFT), and dominance genetic effects were observed for BFT with nt167 and intramuscular fat (IMF) contents with nt80. Our results concluded that the FABP3 polymorphisms can be used as genetic markers in breeding programs for IMF content as well as carcass BFT.