Tackling proteome changes in the longissimus thoracis bovine muscle in response to pre-slaughter stress

Abstract

Pre-slaughter stress has adverse effects on meat quality that can lead to the occurrence of Dark Firm Dry (DFD) meat in cattle. This study explores the previously uncharacterized proteome changes linked to pre-slaughter stress in the longissimus thoracis (LT) bovine muscle. Differential proteome profiles of DFD and normal (non-DFD) LT meat samples from male calves of the Rubia Gallega breed were assessed by 2-DE coupled to MS analysis (LC-MS/MS and MALDI TOF/TOF MS). A total of seven structural-contractile proteins (three different myosin light chain isoforms, two fast skeletal myosin light chain 2 isoforms, troponin C type 2 and cofilin-2) and three metabolism enzymes (triosephosphate isomerase, ATP synthase and beta-galactoside alpha-2,6-sialyltransferase) were found to have statistically significant differential abundance in sample groups. In addition, 2-DE in combination with the phosphoprotein-specific fluorescent dye Pro-Q DPS revealed that highly phosphorylated fast skeletal myosin regulatory light chain 2 isoforms underwent the most intense relative change in muscle conversion to DFD meat. Therefore, they appear to be the most sensitive biomarkers of stress just prior to slaughter in Rubia Gallega. Overall, these findings will facilitate a more integrative understanding of the biochemical processes associated with stress in cattle muscle and their effects in meat quality.