Environmental and nutritional effects on beef tenderness in Texas
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Effects of three environments and their native or rye pasture forage systems on subsequent carcass characteristics, composition, and meat palatability were examined following grain feeding. Calves (F2 Angus x Bos indicus) with similar pre-weaning management and genetics were randomly assigned to one of eight treatments (McGregor-Calf; McGregor-Low; Uvalde-Low; Uvalde-High; Overton-Low, Rotational; Overton-Low, Continuous; Overton-High, Rotational; and Overton-High, Continuous). After approximately five months of grazing, cattle in forage groups were transported to McGregor and finished on a corn-milo ration to visually assessed 10 mm fat thickness. Longissimus muscle sections were randomly assigned into aging periods of 1, 7, 14, 21, 28, or 35 days and two-2.54 cm steaks were removed per section for Warner-Bratzler shear force and trained sensory analysis. After grazing, steers fed diets designed to produce higher rates of gain weighed more than steers at the same location fed diets designed for lower rates of gain. Within the high nutrition treatments, Uvalde-High steers had a lower average daily gain than steers in the Overton-High treatments. Differences in environment and nutritional treatments induced differences in rate of gain during the stocker phase. All forage treatment groups increased average daily gain in the feedlot phase. After the feedlot phase, steers varied in live weight due to treatment. Nutritional/environmental treatments affected ribeye area; kidney, pelvic and heart fat; and hot carcass weight, but not final yield grade. Treatment had minimal affects on quality grade characteristics. There was no affect by treatment on Warner-Bratzler shear force or sensory panel perception of myofibrillar tenderness, connective tissue amount, overall tenderness, or overall flavor intensity. Storage day affected shear force; steaks were toughest at 1 and 7 days of storage with shear force values decreasing after 7 days of storage. There was no interaction between environmental/nutritional treatment and storage day. Juiciness and cook loss were affected by treatment (P=0.0001). Overall, environment and nutrition had little impact on eating quality. Despite differences in average daily gain, it appears that steers may be fed forage diets followed by grain feeding to a similar fat thickness endpoint and produce steaks that are similar in palatability to grain-fed steers.
Peach, Jody Lynea (2003). Environmental and nutritional effects on beef tenderness in Texas. Master's thesis, Texas A&M University. Texas A&M University. Available electronically from