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

Abstract

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.

Early Postmortem Proteome Changes in Normal and Woody Broiler Breast Muscles

“…TRFE (TF), a transport protein, connects the two functional groups for muscle structure and carbohydrate metabolism. In our previous study, we found that TRFE was more abundant in WB than in NB at 24 h postmortem, indicating a stressed physiological condition in WB, according to a study conducted by Awad et al, whereas the decreased TRFE in postmortem WB may be a result of more drip loss due to the weakened protein structure. Because of the iron-binding ability, TRFE has an antibacterial effect, since iron is one of the essential nutrients for bacterial growth .…”

“…HSP27 degradation was positively correlated with protein degradation and meat tenderness. In our previous study on the proteomic differences between NB and WB, we found that HSP27 was more abundant in WB than in NB tissue postmortem, potentially due to a higher pH and greater oxidative stress. The extent of HSP27 decline postmortem was related to higher ultimate pH values, with higher values associated with higher levels of HSP27 .…”

“…In this study, the degradation was much weaker, with only 15 amino acids being removed from the full-length protein when compared with the study of Soglia et al, who reported a progressive accumulation of a 39 kDa desmin degradation fragment in WB meat. DES is a reliable marker of the regenerative processes that occur in chicken breasts, and it was found to be more abundant in WB compared to NB right after death . Troponin I proteins play an important role in the calcium regulation of contraction and relaxation.…”

“…Muscle protein oxidation processes can induce conformational and functional modifications of protein, including enzyme activity. WB birds experience more oxidative stress and exhibited higher protein and lipid oxidation, which may lead to the differences in the oxidation rate in the muscle regulating the endogenous enzyme activation. Therefore, the degradation of desmin, troponin, and TRFE found in the WB meat but not in NB could be attributed to the faster muscle oxidation and higher endogenous enzyme activity in the WB muscle.…”

“…The genetic selection of fast-growing and high breast yield broilers is accompanied by an increased susceptibility to growth-related myopathies, including white striping, woody breast (WB), and spaghetti meat. , Numerous studies have shown that, compared to normal breasts, WBs exhibited unpleasant appearance, a reduced myofibrillar protein content, disorganized sarcomere structures, more crosslinked collagen, more necrotic fibers, lower water-holding capacity, decreased product yield, and impaired sensory qualities. − Although the etiology of the WB development is not clear, it is well accepted that WB-affected broilers are under conditions of oxidative stress, ,, which subsequently impacts their energy homeostasis, ion homeostasis, osmotic balance, protease and lipase systems, and proteins in skeletal muscles . These antemortem differences exert influence on the biochemical changes that occur postmortem.…”