Proteomic Characterization of Normal and Woody Breast Meat from Broilers of Five Genetic Strains

Woody breast (WB) is an emergent broiler myopathy that is macroscopically characterized by hardened areas of the Pectoralis major muscle. Five genetic strains (strains 1–5) of mixed-sex broilers were fed either a control or an amino acid (AA)-reduced diet (20% reduction of digestible lysine, total sulfur AAs, and threonine) for 8 wk. Differences between whole-muscle proteome profiles of normal breast (NB; n = 6 gels) and WB tissue (n = 6 gels) were characterized for (1) broiler strains 1–5 that were fed with a control diet and collected at 0 min; (2) strain 5 (control diet) that were collected at 15 min, 4 h, and 24 h; (3) strain 5 (0 min) that were fed with a control and an AA-reduced diet. Birds that yielded WB were heavier and had a greater pH at death (pH0min) than normal birds. Results indicated that 21 proteins were more abundant (P < 0.05) and 3 proteins were less abundant (P < 0.05) in WB compared with NB. The differentially abundant proteins in each comparison were consistently upregulated or downregulated in WB tissue although the different protein profiles were noticed for each comparison. Strains 2 and 5 had more protein profile differences between WB and NB meat than strains 1, 3, and 4, which potentially indicates a stronger genetic component for strains 2 and 5 with respect to WB formation. The proteins that were more abundant in WB compared to NB are involved in carbohydrate metabolism, oxidative stress, cytoskeleton structure, and transport and signaling. Ingenuity Pathway Analysis indicated that regulated pathways in WB were mainly related to carbohydrate metabolism, cellular repair, cellular organization and maintenance, and cell death and survival. The results support the potential causes of WB myopathy, including the presence of hypoxia, oxidative stress, increased apoptosis, misfolded proteins, and inflammation.