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Animal Breeding, Genetics, & Genomics

Commercialized genetic markers for the swine industry

Genetic markers, significantly associated with growth, leanness and meat quality, have now been made available to all pork producers in the US.  The Iowa State University Research Foundation has recently signed a licensing agreement with GeneSeek Inc. of Lincoln, Nebraska and DNA Landmarks, Canada.  The agreement licenses the use of DNA markers in 5 genes which have been previously well tested and commercially validated by a large pig breeding company.  Royalty fees per test were set  low to encourage widespread use of the markers. It is expected that over 70% of the pigs produced in the US come from breeding stock in which one or more of these genetic markers were used. The gene markers are:MC4R. The producer and breeder can decide if they wish to choose the “fast” growth or the “lean/efficient growth” form of the gene. 

Effects are 3 days less to market weight for animals homozygous for the growth allele compared to those homozygous for the lean allele.  Pigs homozygous for the lean allele have 8% less backfat and eat significantly less feed.  Breeders can choose which characteristic, growth or leanness, is best for their program. These results have been well validated and are effective in all breeds tested to date except Hampshire.

  • PRKAG3.  Producers and breeders can select for animals having the high pH and better meat color form of the gene.  Animals having this beneficial genotype have a pH of nearly 0.1 higher in their loin and ham samples than those animals that are homozygous for the non beneficial allele. Effects are seen in all major breeds.
  • CAST. This gene  affects tenderness and meat quality.  Producers can test and select those animals that are likely to produce more tender meat and improved meat quality.
  • HMGA1. This gene  is highly associated with backfat and lean growth. Producers can test and select animals which are likely to be leaner and produce offspring that are leaner.
  •  ESR.  The ESR gene is related to reproduction and is recommended for Large White and Yorkshire breeds to improve litter size.

These production genes are best used in combination.  Use of all four, MC4R, PRKAG3, CAST and HMGA1, would be beneficial for overall line development to improve growth, leanness and meat quality.  A combination of MC4R (growth allele) and HMGA1 could be used for growth and backfat improvement only, or MC4R (lean allele) and HMGA1 could be used together for significant leanness in breeding stock.  Finally, PRKAG3 and CAST could be used in combination to improve meat quality.  Breeders and producers should work to develop the best multi-gene combination for their lines.

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