Research Note: Expression levels of collagen-related genes in PSE conditions and white striping features of broiler pectoralis major muscle

Abstract

The objective of this study was to compare the meat quality characteristics and collagen-related gene expression levels in the broiler pectoralis major ( PM) muscle among the meat quality groups, including normal, pale, soft, and exudative ( PSE), and white striping ( WS) groups. The group was classified by their WS degree (moderate or severe striping) and quality traits including pH and lightness values at 24 h postmortem (normal group: pH _{24 h} ≥5.7, 48≤ L*≤53, without WS features; PSE group: pH _{24 h} <5.7, L* >53, without WS features; WS group: pH _{24 h} ≥5.7, 48≤ L*≤53, with moderate or severe striping). The WS group revealed no differences in all measured meat quality traits compared to the normal group ( P > 0.05). PM muscles exhibiting PSE conditions without WS indicated lower pH _{15 min} and pH _{24 h} values ( P < 0.05). Whereas, lower lightness and cooking loss values were observed in the normal and WS groups compared to the PSE group ( P < 0.05). No significant difference was observed in the level of type I collagen among the groups ( P > 0.05), whereas a higher type III collagen level was observed in the WS group than in the other groups ( P < 0.05). Additionally, the WS group showed a higher type IV collagen level compared to the normal group ( P < 0.05) and a level not different from that of the PSE group ( P > 0.05). In contrast, the expression levels of matrix metalloproteinase ( MMP ) 2, involved in type IV collagen degradation, and angiopoietin-like protein 7, associated with collagen accumulation, were higher in the WS group compared to the normal group ( P < 0.05). However, no difference was detected in the MMP1 level among the all groups ( P > 0.05). These results suggest that the occurrence of WS features in broiler PM muscle, unlike PSE and normal conditions, can be influenced by the expression levels of collagen-related genes associated with abnormalities in extracellular matrix components.