Results
Heart Fatty Acid Binding Protein
Intramuscular fat percentage (IMF) has been found to be positively associated with sensory attributes of pork (Fernandez et al., 1999; Touraille et al., 1989). Hovenier et al. (1992) reported that backfat reduction is not completely related with reductions in IMF. Therefore, it may be possible to treat the two traits separately in a breeding scheme with the proper selection tools.
Heart Fatty Acid Binding Protein-1 (HFABP) is a member of the fatty acid binding protein family (FABP), which is involved in fatty acid transport from the cell membrane to the intracellular sites of fatty acid utilization (Veerkamp and Maatman, 1995). Given this physiological role, HFABP has been considered to be an interesting candidate gene for IMF and backfat (BF) in pigs. Gerbens et al. (1997) mapped HFABP to pig chromosome 6. The QTL studies have also identified IMF and BF loci in this region of chromosome 6 (Ovilo et al. 2000b; de Koning et al., 1999), further implicating HFABP as a strong candidate gene for IMF and backfat in the pig.
Gerbens et al. (1997) reported three polymorphic sites in the porcine HFABP gene (HaeIII, MspI, and HinfI) and conducted an association study to determine the genotype effects on traits in pigs (Gerbens et al., 1999). This study reported IMF and BF differences between HFABP genotype groups and thus hypothesized that HFABP, or a closely linked marker, controlled IMF differences in pigs. Two of these markers were also informative in a Norwegian pig population (E. Grindflek, personal communication), and Ovilo et al. (2000a) also reported differences in genotype groups for the HFABP HaeIII PCR-RFLP.
Results from our population show that the HaeIII HFABP PCR-RFLP (originally reported by Gerbens et al., 1997) is polymorphic in Berkshire, Duroc, Landrace and Hampshire populations. The frequency of allele 1 was 0.63. Total population analysis reveals effects of HFABP on ultimate loin pH (P<0.05) and quality index (P<0.01) (Table 1), and intramuscular fat percentage and pork flavor also showed interesting trends. The results of the individual breed analysis (not shown) revealed differences between HFABP genotypes and loin muscle area, loin glycogen concentration, intramuscular fat, Instron tenderness, and quality index for Berkshire. The Berkshire analysis results are similar to those of Gerbens et al. (1999), which found an advantage of the HaeIII HFABP 12-heterozygote for intramuscular fat percentage and backfat. Loin glycogen concentration was also significantly different (P<0.05) in Duroc; last rib backfat, flavor score, and water holding capacity for Hampshire; and last rib backfat, and intramuscular fat for Landrace. HFABP remains an interesting candidate gene for meat quality traits of importance within specific breeds of swine.