Evaluation of beef carcass quality using the muscle eye area M. longissimus dorsi

In Japan, Korea, the USA, and Australia, the area of the “muscle eye” (cross-section of the M. longissimus dorsi during the division of the half-carcass between the 12th and 13th rib into the front and rear parts) is used to assess the quality of cattle carcasses. The correlation between this feature and the slaughter and quality characteristics of carcasses in 20-22-month-old crossbred bulls (Ukrainian Black-and-White Dairy × Holstein) has been studied. The area of the “muscle eye” in bulls was determined before slaughter by an ultrasound analyzer Emperor 860. After slaughter, it was calculated by the length and depth of the "muscle eye". The colour of muscle and adipose tissue, carcass conformation, development, and subcutaneous fat thickness have been examined. The correlation between the size of the "muscle eye" and carcasses' quantitative and qualitative characteristics has been determined. The area of the "muscle eye" has a positive relationship (r = 0.612; p >0.999) with live weight after fasting, carcass weight (r = 0.598; p >0.999), flesh weight (r = 0.498; p >0.99), including the highest (r = 0.745; p >0.999), and first grade (r = 0.662; p >0.99), the amount of adipose tissue (r = 0.491; p >0.99) and tendons and ligaments (r = 0.435; p >0.99). With its increase, there is a tendency to an inverse relationship with the content of second-grade flesh in the carcass (r = 0.303), carcass conformation (r = 0.147), fat-irrigation thickness (r = 0.125), and marbling (r = 0.340). The area of the "muscle eye" is inversely correlated with the development of subcutaneous fat (r = -0.389; p >0.95) and the saturated colour of muscle tissue (r = -0.309). The correlation coefficients between the area of the "muscle eye" determined by ultrasound and quantitative and qualitative characteristics of carcasses are significantly higher than those obtained by post-slaughter calculation of the area of the muscle eye by measuring the length and depth. The data's practical significance is obtaining knowledge that allows beef to be sorted based on the correlation between the muscle eye area and the quality of carcasses and beef.