Identification of meat quality-related differentially methylated regions in the DNA of the longissimus dorsi muscle in pig

The objective of this study was to investigate the association of DNA methylation with postmortem energy metabolism and the pH of the porcine longissimus dorsi muscle (LDM). Analysis of the DNA methylome of eight LDM samples (four pairs of the highest and lowest pH among littermates) identified a total of 3468 differentially methylated regions (DMRs) between high and low pH samples (p ≤ 0.001). Of DMRs, 45.3% co-mapped with quantitative trait loci known to be associated with meat pH and postmortem metabolism. Among the DMRs, 203 hyper-methylated regions (HR) and 190 hypo-methylated regions (HO) were identified for the high pH group compared to the low pH. Furthermore, 44 and 21 protein-coding genes contained HR and HO in their gene body, respectively. It was revealed that ENO1, GYS2, SDHC and DERA, which encode core enzymes in postmortem energy metabolism, contained HR or HO in their gene body.

Comparison and relationship between meat colour and antioxidant capacity of different pig breeds

The objectives of this study were to evaluate meat colour, antioxidant performance of longissimus muscle in different pig breeds, including five Chinese native pig breeds, a Chinese bred pig breed as well as a commercial crossbred pig breed, and to analyse the relationships between meat colour and antioxidant capacity. The results showed that the Chinese native and bred pig breeds have higher meat colour and marbling scores than commercial crossbred pigs. The Chinese native and bred pig breeds showed significantly stronger total antioxidant capacity and superoxide dismutase activity, and lower malondialdehyde contents than commercial crossbred pigs. Moreover, the total antioxidant capacity, superoxide dismutase activity were positively correlated with visual colour, a* and chroma, and negatively correlated with L* and hue angle; on the contrary, the malondialdehyde content was negatively correlated with visual colour, marbling, a*, b* and chroma, and positively correlated with L* and hue angle. In addition, principal component 1 and 2 explained 46.41% and 18.30% of the total variance. These results indicated that meat colour and antioxidant capacity were affected by pig breeds, and meat colour was strongly correlated with antioxidant capacity.

Meat and nutritional quality comparison of purebred and crossbred pigs

Crossbreeding is an effective method of improving the efficiency and profit of production in commercial pig operations. To understand the effect of crossbreeding on meat and nutrient quality, a combination including three purebred (Duroc, D; Landrace, L; Yorkshire, Y) and two crossbred pig lines (Landrace × Yorkshire, LY; Duroc × (Landrace × Yorkshire), DLY) frequently used internationally were studied. The results showed that meat from the LY and DLY crosses had lower values for lightness L24h∗, shear force and epinephrine and higher values for drip loss, C18:1, insulin, glucagon and monounsaturated fatty acids than D, L and Y pigs. Moreover, LY had higher values for post mortem pH and lower values for a* and b* than the purebreds. In contrast, DLY had lower values for pH and higher values for a* and b* than the purebreds. Meat quality-related gene analysis showed that the CAST, IGF2 and MC4R gene expression levels in the LY and DLY pigs were significantly higher than those in the D, L and Y pigs. These results indicate that crossbreeding can alter the meat quality, nutritive value, energy metabolism and gene expression of pigs. Future research should focus on microRNA expression and DNA methylation that regulate gene expression and thus affect the meat quality.

Correlation between three glycometabolic-related hormones and muscle glycolysis, as well as meat quality, in three pig breeds

BACKGROUND

The present study aimed to evaluate the correlations among muscle concentrations of three glycometabolic-related hormones (insulin, epinephrine and glucagon), muscle glycolysis and meat quality in representative muscles of either glycolytic or oxidative types. Moreover, the relative glycometabolic-related gene expression was measured. One Western crossbreed DLY (Duroc × (Landrace × Yorkshire)), one crossbreed with half-Chinese native-pig origin DL (Duroc × LiangShan) and one pure Chinese native pig TP (Tibetan pig) were used in the present study.

RESULTS

Among the three breeds, DLY had the greatest glucagon and epinephrine (P < 0.01). Compared with DLY, TP and DL had lower lactic acid concentrations, showing lower glycolytic potentials (GP), greater ultimate pH values (P < 0.01) and lower relative expression levels of glycometabolic-related genes (GYS1, PRKAG3 and PKM2). Compared with the glycolytic muscle (musculus longissimus dorsi), oxidative muscle PM (musculus psoas major) had lower glucagon and epinephrine contents, lower GP and better meat quality. The concentration of glycometabolic-related hormones in the muscle had significant correlations with muscle glycolysis, meat pH and lightness.

CONCLUSION

The results obtained in the present study imply that glucagon and epinephrine levels could be used to indicate early glycolytic metabolism during postmortem. These findings may be helpful in identifying pork with undesirable quality traits. 2016 Society of Chemical Industry.