Exploring the Factors Contributing to the High Ultimate pH of Broiler Pectoralis Major Muscles Affected by Wooden Breast Condition

Abstract

The elevated ultimate pH (pH u ) found in wooden breast (WB) meat suggests an altered muscular energetic status in WB but also could be related to a prematurely terminated post-mortem pH decline. The aims of this study were to explore the factors contributing to the elevated pH u and establish whether the occurrence of WB defect alters muscle post-mortem carbohydrate metabolism and determine if the contractile apparatus reflects such changes. A total of 24 carcasses from Ross 308 male chickens were obtained from a commercial producer and harvested using commercial processing procedures. Carcasses were categorized into unaffected (NORM) and WB groups (n = 12 each), and samples were collected from cranial bone-in pectoralis major (PM) muscles at 15 min and 24 h post-mortem for the determination of pH, glycolytic metabolites, adenonucleotides, buffering capacity, phosphofructokinase (PFK) activity, and in vitro pH decline. Twenty-four additional deboned PM samples (12 NORM and 12 WB) were collected from the same processing plant to assess muscle histology and sarcomere length at four different locations throughout the PM muscle. Data show that the reduced glycolytic potential of WB muscles only partially explains the higher (P < 0.001) pH u of WB meat, as residual glycogen along with unaltered PFK activity suggests that neither glycogen nor a deficiency of PFK is responsible for arresting glycolysis prematurely. The dramatic reduction in ATP concentrations in the early postmortem period suggests a defective ATP-generating pathway that might be responsible for the reduced pH decline in WB samples. Further, the addition of excess of ATPase extended post-mortem glycolysis of WB meat in an in vitro glycolytic system. WBaffected samples have longer (P < 0.001) sarcomeres compared to NORM, indicating the existence of compromised energy-generating pathways in myopathic muscles that may have had consequences on the muscle contraction and tension development, as in vivo, also during the post-mortem period. Considering the overall reduced

Muscle Metabolome Profiles in Woody Breast-(un)Affected Broilers: Effects of Quantum Blue Phytase-Enriched Diet

“…It has been shown that a defect in glucose-6-phosphate concentration was a major contributor to reduce whole-body insulin-mediated glucose disposal rates and to reduce insulin action on glycogen synthase (42). Although it was not measured in the present study, dysregulation of glucose-6-phosphate levels indicated an alteration of glycogen content in muscle with WB (8,43). This is supported here by the increased levels of AICAR, which has been reported to alter glycogen content via alteration of glycogen synthase and glycogen phosphorylase activities (44).…”

Weighted gene co-expression network analysis identifies molecular pathways and hub genes involved in broiler White Striping and Wooden Breast myopathies

“…Furthermore, ER dysfunction has important consequences for insulin secretion and glucose metabolism alteration 44 , 45 , which agrees with the modified glycolytic enzymes expression previously found in abnormal breasts 5 . These statements could also explain the severely altered glucose metabolism identified by Lake and Abasht 20 and Baldi et al 46 in broilers affected by WB. In addition, the same Authors pointed out the importance of the endothelial cell damage and the apoptosis promoted by UPR in the occurrence of the growth-related muscular abnormalities in broilers, in accordance with the potential pathogenic mechanisms of COL4A1-related myopathies.…”

The Potential of Guanidino Acetic Acid to Reduce the Occurrence and Severity of Broiler Muscle Myopathies

“…Broilers with WB have a dramatic reduction in ATP concentrations in the early postmortem period. This finding indicated a faulty ATP-generating pathway that might be related to the higher ultimate pH in WB samples (Baldi et al, 2020). In muscles with low ATP and creatine, GAA can be a direct substrate and thoroughly saturate CK and serve as compensatory phosphagen.…”

“…These beneficial results of GAA on WB incidence and severity could be explained by its role on reducing insulin resistance, sparing Arg to increase vasodilation, improving antioxidant capacity ( Ostojic, 2015a ), and the energetic balance in muscles due to an increase in muscle creatine and as such help supply ATP and proper muscle function during growth ( Baldi et al, 2020 ). Ibrahim et al (2019) observed that GAA + 0.4% Met was superior to creatine to enhance gene expression of insulin growth factor-1, growth hormone, and muscle myogenin and downregulate myostatin in mulard ducks.…”

“…Recent findings have linked their onset with hypoxia (Malila et al, 2019) due to reduced vascularization (Sihvo et al, 2018), phlebitis (Papah et al, 2017;Chen et al, 2019), and glucolipotoxicity (Mutryn et al, 2015;Abasht et al, 2016;Lake and Abasht, 2020). The final result is a muscle with defective energy-generating pathways combined with a deficiency and/or dysfunction of tissue ATPases, having consequences in myodegeneration and on muscle fiber contraction degree (Baldi et al, 2020). Genetics and factors related to early development, environment, and nutrition could be involved in the onset of these conditions (Bailey et al, 2015;Montagna et al, 2019;Petracci et al, 2019).…”