The consumers` eating experience is a primary factor influencing their purchasing decision. Pork eating quality is mostly linked with the overall acceptance, juiciness and tenderness, with tenderness being considered the most important feature of consumer satisfaction. Therefore, improving pork tenderness is important for the pork industry so as to better satisfy consumer preference for a consistent and pleasurable eating experience.

Tenderness evaluation usually is the result of scoring done by trained or consumer panelists.

However, this kind of evaluation is expensive, difficult to organize, and time consuming, regardless of whether the panelists are trained professionals or consumers.

Consequently, instrumentation methods that can accurately reflect the meat tenderness ratings generated by panels have been developed. Warner-Bratzler shear force (WBS) is the most widely used estimator of tenderness. It can used with raw meat and is suitable for commercial application.

A recent report showed that the WBS has significant and favorable correlations with the panelist tenderness evaluation variables, such as softness (-0.18), initial tenderness (-0.23), chewiness (-0.27), and rate of breakdown (-0.26) (Choe et al., 2016).

There are many factors influencing pork shear force, and of course genetics is one of the most important determinants that explains about 30% - 40% (heritability) of the variation in shear force (Ciobanu et al., 2011 and Miar et al., 2014).

Tenderness is also positively correlated with many other meat quality traits, such as marbling score and intramuscular fat (0.32) (DeVol et al., 1988). The focus on selection for lean yield (mainly reduced backfat) in the past decades has resulted in a reduction in marbling, however, the correlation between marbling and backfat is less than one so there is opportunity to select for more marbling, and its associated improvement in tenderness while also reducing backfat.

Consumers demand pork with minimal visual fat even though it results in a less favorable eating experience. Genetic improvement can play a significant role in improving marbling and tenderness while reducing backfat. However, it is difficult to satisfy this consumer requirement using only traditional breeding methods due to the high cost of shear force measurement and the limited amount of pork quality data available post-mortem.

Including genomic information into the genetic improvement program may provide a good solution to achieve this end. To date, about 191 regions of the genome (or QTL) have been detected for pork shear force (PigQTLdb, release 30, August 29, 2016). Recently high-density SNP chips (60K, 80K, 650K and even whole sequence wide SNPs) and improved genomic methods have been increasingly used to identify more precise markers for pork tenderness (Nonneman et al., 2013; Zhang et al., 2016).

Genesus Inc. has conducted a carcass and pork quality program since 1998. A recent Genesus genomic study on pork quality identified four important SNP markers on chromosomes 2 and 17 which significantly affect pork peak shear force. Animals with the favorable genotypes have significantly improved tenderness (decreased shear force).

As shown in the figure below, for the marker on chromosome 2, pork shear force for animals with BB (favorable) genotype was about 8 units lower than that from animals with AA (unfavorable) genotype. So pigs with the favorable genotype (BB) are anticipated to improve consumer pork tenderness.

Most recently Genesus Inc. can utilize SNP chips to assist in the improvement of pork quality. We also tested the feasibility of using genomic markers to improve the genomic evaluation for tenderness and other important meat quality traits. Incorporation of these results along with continual improvement of the genomic technologies will enhance the Genesus genetic improvement program for pork quality, and consequently enhance the ultimate goal of increasing profitability for Genesus customers.

Reference list:

Choe, J. et al., 2016. Estimation of Sensory Pork Loin Tenderness Using Warner-Bratzler Shear Force and Texture Profile Analysis Measurements. Asian Australas. J. Anim. Sci., 29(7): 1029-1036

Ciobanu, D.C. et al., 2011. Genetics of Meat Quality and Carcass Traits. Genetics of the Pig, 2nd Edition: 355–389.
De Vol, D.L. et al., 1988. Variation in composition and palatability traits and relationships between muscle characteristics and palatability in a random sample of pork carcasses. J. Anim. Sci. 66 (2): 385-395.

Miar, Y. et al., 2014. Genetic and phenotypic parameters for carcass and meat quality traits in commercial crossbred pigs. J Anim Sci 92: 2869 - 2884.

Nonneman, D.J. et al., 2013. Genome-wide association of meat quality traits and tenderness in swine. J Anim Sci 91: 4043–4050.

Zhang, C. et al., 2016. Genome Wide Association Studies (GWAS) Identify QTL on SSC2 and SSC17 Affecting Loin Peak Shear Force in Crossbred Commercial Pigs. PLoS ONE 11(2): e0145082.