RESUMO
The most common pork quality problems are pale, soft, and exudative (PSE) and acid pork (AP). PSE is associated with the expression of recessive halothane (Hal) allele Haln. Recessive Hal pigs (Halnn) have defective Ca2+ release channels (CRC) or Ryanodine Receptors (RYR1) within the sarcoplasmic reticulum that allow uncontrolled release of Ca2+ in response to stress. Abnormal lactic acid metabolism caused by stress prior to slaughter leads to the sudden drop in postmortem muscle pH producing the PSE pork. Conversely, AP is caused by the dominant RN- allele of the Rendement Napole gene. RN- pigs have high glycolytic potential that causes the lower ultimate pHu due to excessive lactic acid production postmortem. Poor water holding capacity of muscle cells in PSE and AP causes excessive drip loss leading to low cooking and processing yields. The conventional methods to evaluate Hal and RN genotypes are less effective compared to the more accurate gene marker tests. Selection against the Haln and RN- alleles by genomic selection can potentially reduce the frequencies of the defective genes with high accuracy in less time. As more quantitative trait loci (QTL) are identified, pig breeders are able to select traits more effectively to increase efficiency of pig production and enhance pork quality.