Altered expression of lactate dehydrogenase and monocarboxylate transporter involved in lactate metabolism in broiler wooden breast

Authors: ZHAO, DAN - Texas A&M University; Kogut, Michael - Mike; Genovese, Kenneth - Ken; HSU, CHUAN-YU - Mississippi State University; LEE, JASON - Texas A&M University; FARNELL, YUHUA - Texas A&M University

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/19/2019
Publication Date: 1/1/2020
Citation: Zhao, D., Kogut, M.H., Genovese, K.J., Hsu, C., Lee, J., Farnell, Y.Z. 2020. Altered expression of lactate dehydrogenase and monocarboxylate transporter involved in lactate metabolism in broiler wooden breast. Poultry Science. 99(1):11-20. https://doi.org/10.3382/ps/pez572.
DOI: https://doi.org/10.3382/ps/pez572

Interpretive Summary: The wooden breast condition (WBC) is a muscle flaw observed in chicken breast meat that is an emerging issue to the poultry industry. Breast meat with the WBC is characterized by areas of hardness and overall muscle rigidity. Although the WBC is associated with fast-growth rates in chickens with high breast meat yield, the specific causes are unknown. Chicken with “woody breast” pose no threat to the health of consumers, but WBC does appear to be an issue with the quality of the meat (texture and appearance), not the health or nutritional make-up of the meat. The condition is sporadic and affects a very small percentage of birds (10%). Even though it's harmless to humans, diners aren't exactly pleased when they're served up a plate of woody chicken that has been described as "tough," "chewy," and "doesn't feel right in the mouth.” The purpose of this study was to try to understand what chemical changes occur in the breast meat of chicks that lead to the growth of wooden breast. The results suggest a chemical reaction occurs in birds with wooden breast that is not found in the meat of normal birds. Why this chemical reaction occurs is not known, but perhaps changing the diet of the chicks can help get rid of this flaw in the muscle.

Technical Abstract: Wooden breast (WB) results in significant losses to the broiler industry due to reduction in meat quality. While the etiology of WB is unknown, it is believed to be associated with localized hypoxia and decreased lactate levels in skeletal muscles, indicating the presence of altered lactate metabolism in WB. We hypothesized that the expression levels of the major signaling molecules that control the lactate metabolism, including lactate dehydrogenases (LDHA & B) and monocarboxylate transporters (MCT1 & 4), were altered in WB. Therefore, the objectives of this study were to evaluate whether there were changes in mRNA and protein levels of LDHA, LDHB, MCT1, and MCT4 in WB compared to normal breast (NB) muscles. MicroRNA375 (miR-375) expression, known to be inversely associated with LDHB protein expression in cancer cells, was also investigated. The level of LDHA mRNA was 1.7-fold lower in WB tissues than in NB tissues (P less than 0.0001). However, the LDHA protein levels were similar in WB and NB tissues. In contrast, the levels of LDHB mRNA and protein were 8.4-fold higher (P less than 0.0002) and 13-fold higher (P less than 0.003) in WB than in NB tissues, respectively. The level of miR-375 was lower in WB compared to NB muscles (P less than 0.025). The specific LDH isoenzyme activity that converted lactate to pyruvate was 1.8-fold lower in WB compared to NB tissues (P less than 0.01). The level of MCT1 mRNA was 2.3-fold higher in WB than those in NB muscles (P less than 0.02). However, this upregulation was not observed with MCT1 protein expression levels. The expression levels of MCT4 mRNA and protein were elevated 2.8-fold (P less than 0.02) and 3.5-fold (P less than 0.005) in WB compared to NB tissues, respectively. Our current findings suggest the potential roles of LDHB and MCT4 on lactate metabolism and provide a unique molecular elucidation for altered lactate hemostasis in WB muscles of broilers.