Doctoral Dissertations

Date of Award

6-1968

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Animal Science

Major Professor

C. S. Hobbs

Committee Members

J. W. Cole, C. B. Ramsey, M. R. Johnston, W. W. Overcast

Abstract

Eighty-four weanling Hereford steers were used in a two-year study of the effects of three predetermined subcutaneous fat thickness levels on the production efficiency and organoleptic properties of beef. Three rations (low, medium and high energy levels) were fed to produce a fat thickness over the 12th-13th rib of 5 mm., 8 to 10 mm. and 13 to 15 mm. for the three rations respectively, after a 150 to 185 day feeding period. Average daily gains were 1.18 lb., 1.55 lb. and 2.07 lb. The rate of fat deposition was monitored by ultrasonic means. Carcass conformation grade, marbling score and carcass grade were significantly (P<.01l) increased as level of energy in the ration increased. Higher feeding levels tended to produce brighter colored, firmer, finer textured muscle. Ration had no significant effect on flavor and juiciness scores. A tendency for tenderness to decrease as feeding level increased was observed. Carcasses from steers on the highest energy level had significantly (P<.01) lower tenderness scores and higher shear values. Significant (P <.01) negative relationships were found between tenderness and marbling score (r = -.35) carcans grade (r = -.40) and fat thickness (r = -.41). Ultrasonic estimates of fat thickness and carcass fat thickness were highly related.

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