INFLUENCE OF STEROID IMPLANTS AND CONCENTRATE FEEDING ON CARCASS AND LONGISSIMUS MUSCLE SENSORY AND COLLAGEN CHARACTERISTICS OF CULL BEEF-COWS

Sixty nonpregnant, mature beef cows were used to determine the effects of steroid implants and concentrate feeding on carcass quality, longi ssimus muscle (LM) collagen characteristics, and LM sensory traits. Tw elve nonfed cows were slaughtered at 0 d to establish basal carcass va lues. The remaining 48 cows were assigned randomly in a 2 x 4 factoria l arrangement to an implant treatment and fed for either 28 or 56 d. T he implant treatments were 1) nonimplanted (controls), 2) a 200-mg tre nbolone acetate (TBA) implant, 3) a 200-mg testosterone propionate + 2 0 mg estradiol benzoate (TEE) implant, or 4) both implants (TBA+TEB). Carcasses from cows fed for 28 and 56 d had improved (P < .05) LM marb ling, lean maturity, and quality grade; a lighter (P < .05) LM color ( higher Hunter L values); a higher (P < .05) percentage of LM soluble (heat-labile) collagen; and a lower (P < .05) LM Warner-Bratzler shear force value (more tender) than carcasses from nonfed cows. Feeding fo r 28 and 56 d also improved (P < .05) LM sensory panel traits of flavo r intensity, connective tissue amount, myofibrillar tenderness, and ov erall tenderness. Feeding cows for an additional 28 d (to 56 d) improv ed (P < .05) LM visual lean color, texture, and firmness and carcass f at color. All LM HunterLab color measurements were higher (P < .05) fo r cows fed for 56 d compared to 28 d, indicating a brighter, redder, m ore vivid color. Implant treatments did not influence (P > .05) carcas s quality or LM color. Steaks from implanted cows compared to controls had (P < .05) more soluble (heat-labile) collagen, a higher percentag e of soluble collagen, and improved sensory traits of tenderness (myof ibrillar and overall) and connective tissue amount. Steaks from TEA-im planted cows compared to the other implant treatments had superior (P < .05) LM sensory evaluations for myofibrillar and overall tenderness. Feeding thin cows a high-concentrate diet for 28 d improved quality g rade and LM sensory traits, and feeding for 56 d improved LM lean and carcass fat color. Implanting fed cows improved LM sensory panel tende rness.