Marbling in the longissimus thoracis muscle from lean cattle breeds. Computer image analysis of fresh versus stained meat samples

One hundred eighty ribeye steaks from Charolais, Limousin and Retinta bulls were used to describe and compare the marbling fat between fresh and stained samples. Image analysis overestimated the intramuscular fat content (P < 0.05) in relation to chemical analysis. Staining had a significant effect (P < 0.05) on most of the marbling fleck traits, showing an increase in the number of marbling flecks and the proportion of marbling fleck area in the whole and in the ventral half of the longissimus m., and a decrease in the size, length and width of marbling flecks. Breed had a significant influence (P < 0.05) on some quantity traits of marbling, but not in the distribution and structure of marbling flecks (P > 0.05). Retinta breed was leaner than French breeds and showed fewer and smaller marbling flecks (P < 0.05). The results showed a positive correlation (r = 0.183 to 0.465) between USDA marbling score, and intramuscular fat by image and chemical analysis.