Effect of myosin heavy chain composition of muscles on meat quality in Laiwu pigs and Duroc

Abstract

In order to explain the mechanism of high meat quality in Laiwu pigs and investigate the relation between myosin heavy chains (MyHC) composition and meat quality, meat quality analysis was conducted and mRNA expression of MyHC I, IIa, IIx, IIb was quantified by real-time fluorescence PCR in longissimus muscle (LM) and semimembranous muscle of Laiwu pigs and Duroc. The result indicated that, compared with Duroc, mRNA expression of MyHC IIa, IIx in LM and semimembranous muscle of Laiwu pigs was significantly increased, mRNA expression of MyHC IIb was dramatically decreased. However, the expression of MyHC I was not significantly affected by breeds. The correlation between mRNA expression of MyHC I, IIa, IIx in LM and meat color, pH value, marbling, intramuscular fat content was positive, but shear value of LM was negative. The relation between MyHC IIb mRNA expression and marbling, intramuscular fat content was dramatically negative, whereas shear value was strikingly positive, as well as fiber diameter, but without reaching statistical significance. Therefore, the composition of MyHC I, IIa, IIx, IIb affected meat quality, furthermore, expression of MyHC I, IIa, IIx, IIb mRNA prominently influenced meat characteristics, especially edible quality of muscle, suggesting that mRNA expression level of MyHC I, IIa, IIx, IIb can exactly and impersonally estimate meat quality.

Differential expression of lipid metabolism-related genes and myosin heavy chain isoform genes in pig muscle tissue leading to different meat quality

“…In general, oxidative metabolism decreases in the rank order MyHCI → MyHCIIa → MyHCIIx → MyHCIIb (Lefaucheur et al, 2002), and these metabolic changes are consistent with the transition of MyHC profile toward a faster type (Lefaucheur et al, 2004). It is well-known that intensive selection for faster muscle growth in Western modern pigs has resulted in a shift in muscle fiber toward a higher glycolytic and lower oxidative metabolism (Lefaucheur et al, 2004;Hu et al, 2008;Guo et al, 2011), which is associated with leaner pigs, better feed efficiency and higher growth rate, but gives rise to a deterioration in meat quality (Lefaucheur et al, 2002;Shan et al, 2009). Previous studies have reported that, compared with the Landrace (Guo et al, 2011), Duroc (Hu et al, 2008) and Large White (Lefaucheur et al, 2004), respectively, the mRNA expression levels of MyHCIIa and MyHCIIx were greater in Jinhua, Laiwu and Meishan pigs, whereas the mRNA expression levels of MyHCIIb were lower.…”

“…It is well-known that pork meat quality traits are affected by the genotype of the pig. For example, the Jinhua pigs (Miao et al, 2009;Guo et al, 2011) and Laiwu pigs (Hu et al, 2008) exhibited better meat quality traits when compared with the Landrace and Duroc pigs, respectively. Moreover, Ruusunen et al (2012) and Shen et al (2014) also found differences in meat quality traits between different genotype pigs.…”

“…It is well-known that different pig breeds show obvious differences in meat quality traits (Hu et al, 2008;Miao et al, 2009;Guo et al, 2011;Ruusunen et al, 2012;Shen et al, 2014); however, up to now, little is known about the molecular mechanisms responsible for the differences. Usually, the differences in meat quality traits are smaller between Western modern pig breeds because of the long-time similar breeding aims such as fast growth and leanness of the carcass (Ruusunen et al, 2012).The Rongchang pig is one of the local fatty-type pig breeds of the southwest area of China with a white coat color phenotype (Lai et al, 2007), and is especially noted for its early sexual maturity, increased IMF content and high meat quality as other Chinese local pigs.…”

“…It is well-known that different pig breeds show obvious differences in meat quality traits (Hu et al, 2008;Miao et al, 2009;Guo et al, 2011;Ruusunen et al, 2012;Shen et al, 2014); however, up to now, little is known about the molecular mechanisms responsible for the differences. Usually, the differences in meat quality traits are smaller between pig breeds that are commonly used for commercial production, because the goals of pig breeding, such as fast growth and leanness of the carcass, have been similar for a long time (Ruusunen et al, 2012).…”

“…Intramuscular fat (IMF) content is an important determinant factor for meat quality traits (Fernandez et al, 1999a). In general, the Chinese local fatty pigs have higher IMF content than Western lean pigs (Young, 1992;Hu et al, 2008;Miao et al, 2009;Zhao et al, 2009;Guo et al, 2011), but the knowledge about the molecular mechanisms is limited. The extent of fat deposition in skeletal muscles depends on the balance between synthesis and degradation of triglycerides (TG), which includes TG synthesis, fat mobilization, fatty acid transport as well as fatty acid oxidation (Zhao et al, 2009).…”