Evaluation of post-mortem change in bovine feeded whit different diet supplementation

Background: The consumer’s growing sensitivity about food characteristics was at first focused for bovine meat on the need to know products origin and then on specific information about meat quality, breeding methods, breed characteristics, animal welfare etc. Sensory properties of meat have an important influence on the purchasing behavior of consumers. Color, juiciness, flavor and tenderness has been shown to be most variable and important sensory component affecting satisfaction with beef. Many factors can affect final meat quality, such as animal welfare, breeding, feeding and transport conditions, slaughtering conditions, electrical stimulation, and chilling conditions. Supplementation of the diet with vitamin E, vitamin C and selenium during the growing and finishing periods may improve meat quality because are a potent antioxidant and has been demonstrated to decrease lipid oxidation, decrease drip loss, increase meat stability and improve the color of meat cuts. Methods: 90 limousine bulls were divided at random into three dietary groups: control, supplementation with vitamin complex and selenium for 30 days before slaughtering and supplementation with vitamin complex and selenium for 60 days before slaughtering. Longissimus Thoracis muscle from the 9th thoracic ribs was collected 2 hours after slaughtering and stored at -80°C. Amounts of 100 mg for each muscle sample have been suspended in 1ml of OMNIzol with addition of protease inhibitor and 20μl of 0.25M EDTA. After homogenization on ice, protein samples have been extracted by OMNIzol Extraction protocol (EuroClone). Protein pellets were suspended in 8M Urea, 4% CHAPS, 1% DTT, 15mM Tris, 2% Ampholine 3.5-10. First dimension was performed using IPG strips pH pH 3-10 NL 18cm and second dimension in 10% polyacrilamide gels. Gels were stained by standard silver nitrate staining protocol. Image analysis was performed with Image Master 2D Platinum (GE) and Progenesis SameSpots software (Nonlinear Dynamics). Results: Identification of the muscle proteome changes relationship to different diet supplement was based on a comparison of muscle samples taken immediately from six animals after slaughter. A synthetic map of bovine muscle proteins was building up. A synthetic gel consists of a representative set of spots generated from several registered gel images. The expression of desmine are decreased respectively, in animal fed with vitamin complex and selenium for 60 days before slaughtering, for 30 days before slaughtering and control animal. Conclusions: 2-DE-based proteome analysis is a useful tool for characterizing expression and metabolism of muscle protein in relationship to different diet or supplementation. Besides, analysis of expression profiles could be a key to find protein markers for meat quality, and give deep understanding of characteristics of different welfare, breeding, feeding, transport conditions and slaughtering conditions. In particular, the decrease of desmin may correlate a better color and tenderness of meat