Carcass characteristics and meat quality of Holstein bulls according to slaughter age and muscle type

Background: Among non-genetic factors, slaughter age is the most significant aspect influencing meat quality traits and quantity of beef. Objective: To compare the effects of slaughter age and muscle type on carcass traits and meat quality of Holstein bulls. Methods: A total of 30 Holstein Friesian bulls were slaughtered at different age, as follows: Young group (YG) at 18 months (n=14 animals); and Old group (OG) at 24 months of age (n=16 animals). Carcass and meat quality traits of longissimus dorsi (LD) and gluteus medius (GM) muscles were evaluated. Results: Carcass traits were not significantly affected over time. Although carcass fat measurements-such as marbling score, back fat thickness, European Beef Carcass Classification System (SEUROP) fatness score-increased numerically with greater slaughter age, only the increase in percentage of kidney, pelvic, and heart (KPH) fat contents were significant (p<0.05). Bulls slaughtered at 24 months had 13.4% greater (p<0.01) LD area than those in the YG group. Bulls in the OG group had significantly (p<0.01) higher slaughter weight as well as hot and cold carcass weights. However, percentages of hot and cold carcass dressing were not significantly affected by slaughter age. The L* (lightness), a* (redness), b* (yellowness), chroma (color intensity), and hue values of meat in the OG group did not differ from those in the YG group. However, L*, a* and chroma values of GM muscle were higher than those of LD muscle, while the pH24 value of GM muscle was significantly (p<0.01) higher than that of LD. Conclusion: It seems more advantageous to slaughter bulls at 24 months of age to get heavier, more marbled, and muscled carcasses better suited to current consumer expectations.