growth-promoting technologies, implants, beta-adrenergic agonists, muscle structure, meat tenderness


Skeletal muscle tissue consists of two main structures that elicit strong influences on cooked meat tenderness: myofibrillar and connective tissues. The myofibrillar component consists of contractile and cytoskeletal proteins that aid in muscle contraction and support. A large portion of meat science literature documents the effects that postmortem aging elicits in terms of weakening the myofibrillar component to improve tenderness. Connective tissue is primarily comprised of collagen, the most abundant protein within the body. The function of this tissue is to support the myofibrillar component and transfer the force of contraction. Collagen, characterized by its solubility, is most commonly identified as the muscle tissue structure that has a large influence on tenderness but is commonly characterized as unaffected by postmortem degradation.

Ractopamine hydrochloride (Optaflexx, Elanco Animal Health, Greenfield, IN) is a beta-adrenergic agonist that directs nutrients away from fat accretion to lean muscle production and is commonly fed during the finishing period of cattle production. Anabolic implants are another growth-promoting technology that increases muscle mass. Numerous studies indicate that both technologies increase muscle mass by increasing the cross-sectional area of muscle fibers. In addition, many studies have demonstrated that both growth promotants negatively affect tenderness, which can be improved by aging. Little is known about the effects of growth promotants or extended aging on collagen solubility. The purpose of this study was to examine the effects of growth-promoting technologies and extended aging on structural muscle characteristics and meat tenderness.


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