Masters Theses

Date of Award

6-1976

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

Haley M. Jamison

Committee Members

William R. Backus, Cecil Carter

Abstract

Seven hundred and twenty-two carcasses from Shorthorn, Angus, Hereford, Charolais and Other Breeds (predominately Simmental X Hereford or Angus) were utilized in an eight year (1968-75) study of breed and year variation in beef carcass yield traits. These steers were entered in the Bristol Junior Steer Show by 4-H and FFA members of East Tennessee and Southwest Virginia. The calves consisted of 15 Shorthorn, 284 Angus, 316 Hereford, 75 Charolais and 32 Other Breeds steers ranging from 360 to 575 days of age. Data collected relative to performance traits (live weight, carcass weight and weight per day of age) indicated a significant (P < .05) advantage of Other Breeds and Charolais carcasses when com-pared to Shorthorn carcasses. There was no significant difference when Other Breeds, Charolais, or Shorthorn were compared to Hereford and Angus. Shorthorn cattle performed lowest in these traits. Angus cattle had the highest mean carcass grade of 12.50 or Low Choice. Other Breeds followed with a 12.10 or Low Choice. Hereford steer carcasses were significantly (P < .05) lower in quality grade than any other of the breed groups. The mean carcass quality grade was 11.88 or High Good for all years and breeds. Carcasses of 1971 cattle were significantly (P < .05) higher with a score of 12.92 or approaching Average Choice. Angus steer carcasses had an average marbling score of 57.10 (Modest Minus) which was significantly (P < .05) higher than the Other Breed groups. Hereford and Charolais steer carcasses had the lowest marbling scores. Although a correlation of 0.87 existed between carcass quality grade and USDA marbling score, the year 1970 had the highest signifi-cant (P < ,05) marbling score. Steers measured an average of 0.44 inches of external fat thick-ness over the twelfth rib. Charolais fat thickness was significantly (P < .05) smaller than the British Breed carcasses. Other Breeds were intermediate in measurements. Cattle slaughtered in 1971, 1972 and 1975 had significantly (P < .05) less external fat thickness. A significant (P < .05) negative correlation of 0.87 existed between carcass fat thickness and percent retail cuts. Ribeye area studies showed that Charolais and Other Breeds had a significant (P < .05) advantage. Shorthorn steers had significantly (P < .05) smaller ribeye area. Year had no significant (P < .05) effect. The estimated overall mean for percent retail cuts was 50.35. Other Breeds and Charolais steers yielded the highest significant (P < .05) percent. Shorthorn steers were predicted (P < .05) to yield the lowest. Live grade with respect to breed and year was not significant. The overall mean live grade was 12.67 compared to an overall mean carcass grade of 11.88 almost one-third higher than actual.

Download
Files over 3MB may be slow to open. For best results, right-click and select "save as..."

Share

COinS