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

The objective of this study was to com-pare 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 strip-ing (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: pH24 h >= 5.7, 48 <= L*<= 53, without WS fea-tures; PSE group: pH24 h <5.7, L* >53, without WS fea-tures; WS group: pH24 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 nor-mal group (P > 0.05). PM muscles exhibiting PSE condi-tions without WS indicated lower pH15 min and pH24 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 expres-sion levels of matrix metalloproteinase (MMP) 2, involved in type IV collagen degradation, and angiopoie-tin-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 extracellu-lar matrix components.