Three-Point Scale of Lipid Concentration and Localization in Muscle Tissue of Birds Using Oil Red O Staining

Research on skeletal muscles includes chemical, sensorial, histopathological, microbiological analysis, and the influence of observed data on meat quality. The aim of this paper was to establish a point scale for analysing the fat concentration in breast and thigh muscles of birds during histological examination. The need for a point scale showing lipid localization arises during the experiment, including the castration of the bird. During necropsy, pectoral and thigh muscles were put into 30% saccharose solution with the addition of sodium azide. Then, frozen samples were cut into 8 µm sections and stained with Oil Red O (Bio-Optica, Milan, Italy) to detect lipids. Four main locations were evaluated: the area around vessels, perimysium between fascicles, endomysium between fascicles, and sarcoplasm of the fibres. Each location was separately evaluated for pectoral and thigh muscles. The percentage of tissue occupied by lipids in different locations was detected using Panoramic Viewer software (3DHISTECH, Budapest, Hungary). The results from the point scale analysis, similar in pectoral and thigh muscles, confirmed data from the chemical analysis. Significant differences were observed in all examined periods in chemical analysis (P<0.05) and were visible in the point scale with a higher number of birds with higher lipid concentration in all examined locations. Our scale analysis of lipid concentration, confirmed by chemical analysis, is an objective tool and can be used separately in muscle tissues in experiments where there is the need for lipid visualization. An established three-point scale can be a tool in poultry muscle tissue evaluation because not only accumulation but also lipid location is crucial in determining the usefulness of meat in culinary processing.