| dc.description.abstract | Three independent studies were done to investigate how genetic factors, carcass management, and exogenous growth promotant programs influence meat quality attributes, palatability, and protein expression in beef. The first study involved Igenity® genetic profiling of myostatin sequence variants C313Y and Q204X of the myostatin gene in Piedmontese-crossbred heifers. Muscle from heifers having 1 or 2 copies of myostatin variants had decreased fat deposition, increased marbling, and minimal influence on quality attributes measured (tenderness and color), indicating a relationship between disruptive myostatin gene alterations and carcass and meat quality traits.
Next, to improve the quality of the under-utilized beef round muscle, a modified hot-boning technique was utilized early post mortem to measure effects on meat palatability and myofibrillar protein degradation in deep and superficial portions of the beef semimembranosus (SM). Randomized treatments included deep SM hot-boned (DH) or cold-boned (DC), and superficial SM hot-boned (SH) or cold-boned (SC). Post mortem temperature and pH decline were monitored every 10 min for 24 h, and at 45 min, 3 h, and 24 h, respectively, in superficial and deep portions of the SM muscle. The deep SM had a slower chill rate and a more rapid pH decline when compared with the superficial SM, regardless of hot-boning treatment, which resulted in increased calpain 1 autolysis in deep SM when compared with superficial SM locations. Muscle from both deep SM treatments was less red, however, tenderness was not different among all treatments. Altering proteolytic activity and meat palatability is contingent upon the ability of the modified hot-boning technique to significantly alter temperature and pH decline in the deep portion of the SM.
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Lastly, proteomic technologies (two-dimensional in-gel electrophoresis coupled with mass spectrometry) were used to identify differentially abundant sarcoplasmic and myofibrillar proteins in the longissimus lumborum (LL) muscle from beef cattle treated with ractopamine hydrochloride with or without anabolic implant treatment during the finishing period. Exogenous growth promoting programs altered the protein profile of beef LL muscle, influencing the abundance of glycolytic enzymes and proteins possessing oxidative resistance, protective, regenerative, recovery, and anti-apoptotic properties that potentially effect meat quality or meat aging. | en_US |
