Beef rib cuts were oven roasted at 107° and 163°C. to end points of 60°, 70°, and 77°C. Cooking losses, tenderness, and other sensory properties were evaluated and related to histological changes in muscle components. Cooking times were longer and cooking losses usually lower at 107°C. than at 163°C. As end point temperature increased, cooking time and cooking loss increased and juiciness decreased. Shear values for cuts heated to end points of 70° and 77°C. at 107°C. were lower than for all other heat treatments. Roasts cooked at 107°C. to each end point and those cooked at 163°C. to 60°C. received higher tenderness scores than did all other heat treatments. Muscle fiber diameter decreased approximately the same extent with heating at either oven temperature. Fiber diameter decreased as end point temperature increased from 60° to 70°C., but diameter increased between 70° and 77°C. Quantity of collagenous connective tissue appeared to be greater in cuts heated at 163°C. to 60°, 70°, and 77°C. and at 107°C. to 70°C. than at other heat treatments. With increasing oven and end point temperatures, collagenous tissue changed from a banded to a granular appearance and fat became dispersed in the perimysial and endomysial collagenous tissue.

Little is known about the physiological effects of short-term fasting in avian species. The present study was developed to examine the alimentary mucosal changes in fasted birds by scanning and transmission electron microscopy. Chickens of various ages were fasted for periods of 3, 5, and 7 days. Water was provided ad libitum. At the end of the fasting periods the birds were sacrificed along with ad libitum fed controls. Tissue samples from crop, duodenum, and ileum were processed by standard methods for scanning and transmission electron microscopy (SEM and TEM). The SEM samples were prepared by vacuum drying methods. The TEM samples were embedded in Spurrs embedding medium. Mucosal sloughing was observed in the crop and small intestine with SEM only in fasted birds. With TEM, separation was observed between the mucosal cells of fasted birds with membranous whorls in these spaces. Sloughed cells may be an endogenous protein source for the fasting bird.

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