Frequency of the Rendement Napole RN- allele in a population of American Hampshire pigs

A total of 204 purebred Hampshire pigs were obtained from 23 breeders. These animals were the progeny of 41 sires and 123 dams. A sample of purebred Yorkshire (n = 24) pigs were also used in the study. Animals were classified by glycolytic potential determined on a live-animal longissimus muscle biopsy sample. Hampshire pigs (n = 176) with glycolytic potential greater than 185 μmol/g (x = 238.8 μmol/g; SD = 29.54) were classified as heterozygous or homozygous for the dominant RN - allele (RN - rn + or RN - RN - , respectively), whereas cohorts (n = 28) with glycolytic potential less than 185 μmol/g (x = 141.3 μmol/g; SD = 24.48) were considered as homozygous normal (rn + rn + ). All Yorkshire pigs (n = 24) had a mean glycolytic potential level of 146.1 μmol/g (SD = 20.18) and were considered as homozygous normal (rn + rn + ). The Hardy-Weinberg equilibrium yielded frequencies of.630 and.370 for the dominant RN - allele and normal rn + alleles in the Hampshire population, respectively, and genotypic frequencies of.397 (RN-RN-),.466 (RN - rn + ), and.137 (rn + rn + ). Hampshires with glycolytic potential ≥ 185 μmol/g had significantly lower longissimus muscle ultimate pH, intramuscular fat, subjective marbling scores, and percentage of protein (P <.001) and had greater longissimus muscle percentage of moisture (P <.001), drip loss (P <.01), and cooking loss (P <.001) than rn + rn + Hampshires and Yorkshires. These data suggest the RN - allele exists at a high frequency within the American Hampshire breed. Higher glycolytic potential levels, which accompany the allele, may cause decreased meat quality.