A dark, firm, dry-like condition in breast meat of roaster chickens condemned for ascites, valgus-varus deformity and emaciation

Abstract

Chicken carcasses with dark, firm, dry traits (DFD) are currently condemned in Canada for cyanosis. Reconsideration of the current policy requires tests for distinguishing DFD carcasses from those that are inadequately bled. Birds in other categories such as ascites (AS), emaciation (EM), and valgus-varus deformity (VVD) may also present a dark carcass color. Chickens condemned for DFD and inadequate bleeding (IB), and also for AS, EM and VVD were collected, and visually separated into "light" or "dark" groups. Color (Commission Intern, de l'Eclairage L*a*b*) and pH were measured at slaughter, on four fixed sites of the pectoralis major. pH was highly and negatively correlated with L* for AS (r = -0.57), EM (r = -0.64), and VVD (r = -0.66). The dark classes of EM and VVD were not significantly different (P >0.05) for pH, L*, and a* from DFD carcasses, but the dark AS class was redder and less acidic than DFD carcasses. Color and pH were not correlated in the inadequately-bled group, which was lighter, less red, and more acidic than the DFD group. Tests based on pH and a*, used to distinguish DFD from inadequately bled carcasses, showed good sensitivity and specificity. The agreement beyond chance between the pH and a* tests was good (Kappa = 0.65). We conclude (1) that a DFD-like condition was present in the dark classes of AS, EM and VVD, and (2) that inadequately bled chickens can be distinguished from those with DFD traits by the use of tests based on pH and a*.