MLBA 10: August / September 2009

 

 

 

 

Rendement Napole (RN) gene is a swine gene found to cause low ultimate pH and water holding capacity (WHC) in pork. The gene is also commonly called the "acid meat gene" or "Hampshire effect" due to the low ul­timate meat pH it causes and because it has primarily been observed in purebred or crossbred Hampshire populations. The negative effects of the RN gene on pork quality result in economic losses in the pork industry; but pork producers can reduce the impact of the gene by adopting RN gene-free poli­cies for their herds.

 

A research study in 1985 identified the relationship be­tween the RN gene and low pH pork. Unlike the porcine stress syndrome (PSS) or Halothane gene, which has incom­plete recessive effects on stress incidence and meat quality, the RN gene appears completely dominant. This dominance implies that a copy of the RN gene inherited from only one parent can cause poor meat quality.

 

In genetic terms, inheritance of the RN gene is at a single locus and there are two alleles: one dominant mutant allele (RN–) and one recessive normal allele (rn+). The dominant RN– allele causes low ultimate pH of all muscles, especially the loin and ham muscles.

 

Each parent provides one allele to his or her progeny, or offspring. Therefore, there are three possible genotypes: ho­mozygous normal (rn+/rn+), heterozygous or carrier (RN–/ rn+) and homozygous mutant (RN–/RN–).

 

For example, if a homozygous mutant boar is mated to a homozygous normal sow, 100 percent of their offspring will be RN gene carriers. The mating of an RN gene carrier boar with a homozygous normal sow will result in 50 percent of the piglets being carriers.

 

The only way to avoid the effects of the RN gene is to breed a homozygous normal sow to a homozygous normal boar. Table 1 lists possible mating combinations and resulting genotypes.