Abstract: Woody breast (WB) has recently been characterized by a distinct hardness of breast fillets. The objective of this study was to determine the basic performance parameters of WB and to identify different grades of WB by microstructural examination and different measures. A total of 147 and 175 Cobb 500 broilers were slaughtered at 42 and 63 days of age following the same procedure, respectively and breast samples were collected for WB classification. The weight, dimensions namely length (L), width (W), top height (H1) and bottom height (H2), and compression force (CF) of all these samples were measured and statistically correlated with WB grades by analysis of variance. Furthermore, a predictive model for WB classification was developed based on the parameters highly significantly correlated with WB grades. The results showed that the microstructure of WB was related to muscle cells with nonuniform size and shape because of muscle degeneration and muscle tissue was replaced by connective tissue when compared to normal breast fillet. For WB samples from carcasses of broilers of the same age, H1, H2 and CF significantly increased as the severity of WB increased (P < 0.05). These three parameters had highly significant correlations with each other, and they were important factors that affected and were correlated with WB categories (P < 0.001). The overall recognition rate of the developed model was 92.30%, suggesting that H1, H2 and CF enables to objectively identify WB and can potentially replace the artificial scoring system.

Key words: poultry meat quality, woody breast, compression force, dimension