The Influence of Muscle Fiber Size on Tenderness in A‐Maturity Heifers1

Abstract

ABSTRACTA total of 77 crossbred late‐maturing or intermediate‐maturing heifers were fed an 84% total digestible nutrient diet from 200 kg live‐weight to slaughter at 433 kg. Carcass data and histochemical samples were obtained at 24 h postmortem, and shear and sensory panel evaluation samples were obtained from the longissimus dorsi muscle afier 7 ahys of aging at 2 to 3°C. Average fiber size was correlated (P< 0.01) to sensory panel tenderness and shear force requirements. Cross‐sectional areas of white, intermediate and red fibers were also correlated (P< 0.01) to shear force requirements. Percentages of white, intermediate and red fibers were not consistently correlated to sensory tenderness or shear force. Evidently, the number of myofibrils per unit of mass was associated with meat tenderness. Research needs to be done to determine iffiber size has a causal relationship with tenderness or is a correlated response to other factors that dictate tenderness.