Associations of DNA markers with meat quality traits in pigs with emphasis on drip loss.

Phenotypic information on 1155 market pigs for several pig meat quality traits, was collected. Genotypes on 12 DNA markers, including RYR1 and PRKAG3 I199V, were also obtained on all pigs to investigate the relationship between genetic markers and meat quality. The RYR1 gene had the highest impact on meat quality, however, several other markers showed significant effects on one or more traits. Animals heterozygous at the RYR1 locus were significantly inferior in almost all meat quality traits, except ultimate pH value, initial conductivity and redness of the meat. Drip loss from case-ready meat (measured from 1 to 7 days post-mortem) was 43% higher for heterozygotes than animals of the stress resistant genotype. The homozygous genotype II at position I199V of the PRKAG3 locus also resulted in less drip loss than genotypes IV and VV, regardless of the method and time of measurement. Furthermore, the favourable genotype related to higher ultimate pH and darker meat. Both loci significantly affected the intercept, linear and quadratic terms of fitted drip loss development curves. The favourable genotypes showed a lower drip loss after one day of measurement and a slower increase and a more linear development over time. Whilst the RYR1 and PRKAG3 markers influenced numerous meat quality traits, some of the other markers were also found to have significant effects on one or two meat quality traits. Markers at MC4R and HMGA1 loci significantly affected drip loss, whereas LDHA, CAST (Hpy188I) and ATP2A1 influenced pH value. In addition, the marker ATP2A1 was associated with variation in intramuscular fat content in M. longissimus dorsi. GLUT4 affected temperature 45min post-mortem and several markers (MC4R, LDHA, GLUT4, HMGA1, CAST (Hpy188I and PvuII)) influenced one or two of the different colour measurements. The markers at MC4R, CKM, AGRP, PRKAG3, and HMGA1 loci were tested for their interactions with RYR1 regarding drip loss. Only AGRP showed a significant interaction, but this was based on only a few animals with the homozygous genotype for one allele. Our results suggest that genetic markers provide a useful tool to improve meat quality in pigs independently from RYR1, especially the mutation I199V in the PRKAG3 gene.

Drip loss of case-ready meat and of premium cuts and their associations with earlier measured sample drip loss, meat quality and carcass traits in pigs.

Drip loss of 374 samples taken from porcine M. longissimus dorsi and M. semimembranosus was measured by using the "bag method" (BM), EZ-DripLoss (EZ-DL) from premium cuts (PC) and in retail tray (case-ready meat; CRM). This provided a comparison between these methods and their relationships to other meat quality and carcass traits. Samples were prepared at 24h post-mortem (pm) and were measured 24 and 48h after preparation (at 48 and 72h pm) using the BM and after 48h (at 72h pm) with the EZ-DL and PC. Drip loss of meat kept in retail trays was measured after 7 days (CRM(7)) and daily within a week (CRM(1-7)). Average drip loss was 1.80% and 3.10% using the BM after 24 and 48h, respectively. EZ-DL and CRM(7) showed higher drip losses of 4.71% and 4.00%. Daily loss of CRM(1-7) showed a concavely shaped curve and increased from 1.57% to 5.64% after 7 days. High correlations were obtained between drip loss of CRM(7) and BM (r=0.88) or the EZ-DL (r=0.91). The development of drip loss in case-ready meat fitted by linear-quadratic regression (y=0.439+1.245x-0.072x(2)) showed that high drip loss measured earlier by bag and EZ-DripLoss methods was highly associated with a high intercept (r=0.63-0.72), a high linear increase (r=0.77-0.81), but larger decrease in increments (r=-0.82 to -0.86) during weekly stored meat in retail trays as supplied at consumer level. Because the positive linear regression coefficient was substantially higher than the negative quadratic regression coefficient, the development of drip loss is mainly dependent on the initial drip loss. Therefore, animals with high drip loss within 72h post-mortem also showed undesirable high drip loss curves over the entire retail period. Relationships between drip loss and other meat quality traits were similar for BM, EZ-DL and CRM(7). Of these the correlation between pH(24) and drip loss was highest with r=-0.54, -0.49 and -0.47 for BM, EZ-DL and CRMH(7), respectively. Interestingly, a correlation of r=-0.35 between blood pH value and CRML(7) was obtained. Carcass traits such as loin, ham, shoulder, belly weight or loin eye area showed only marginal correlations to drip loss. In conclusion, EZ-DL was the most appropriate method to predict drip loss of case-ready meat in retail trays and its development during a 7 day storage period.

Comparison of different methods for determination of drip loss and their relationships to meat quality and carcass characteristics in pigs.

Samples of the M. longissimus dorsi of 776 pigs from three commercial lines were used to compare two methods for measuring drip loss, referred to as the EZ-DripLoss and bag methods. Furthermore, relationships between drip loss and other meat quality and carcass traits were analysed. The bag method used a slice of M. longissimus dorsi of approximately 120 g hung in an airtight container whereas the EZ-DripLoss method used two samples of approximately 10 g placed in drip loss containers. In the bag method, samples taken at 24 h post-mortem were measured 24 and 48 h after sampling and average drip loss was 1.94% and 3.33% at 24 and 48 h, respectively. Correlation between these consecutive measurements was high (r=0.98). Using the EZ-DripLoss method, drip loss of samples taken at 24 h post-mortem was measured 48 h after sampling and showed an average value of 4.97%. Correlation between the drip loss obtained using EZ-DripLoss and bag methods was high (r=0.86). Relationships between drip loss and other meat quality traits were similar for both methods. Highest correlations were observed between drip loss and pH(45) (r=-0.52 and -0.48 using EZ-DripLoss method(48) and bag method(48), respectively) and the lowest to Minolta a (∗) value (r=0.11 and 0.09, respectively). Correlations among several carcass traits, such as lean content, and drip loss were low or not significant. Low associations between loin eye area (cm(2)) and drip loss were obtained regardless of the method used to determine drip loss (r=0.21 and 0.18 using EZ-DripLoss method(48) and bag method(48), respectively). For routine measurements, the EZ-DripLoss method is recommended because it showed a high correlation with the bag method but is easier to perform and is more standardised.