Date of Award
Master of Science
William R. Backus
M.J. Riemann, J.B. McLaren
A total of 90 Angus steer calves varying in body type (frame score 1 to 4) were purchased in October 1980 and wintered (October through March) on stockpiled cool season pasture plus limited hay. The steers were grazed 112 days (April through July) on fescue, orchard grass, and ladino clover. The steers' average weight was 221 kg at purchase, 221 kg at end of wintering, and 317 kg at the end of spring-summer grazing. Following the pasture phase, they were randomly assigned, within frame size, to slaughter groups and were serially slaughtered after 0, 28, 56, 84, 112, and 140 days on a ration of whole shelled corn plus supplement.
The carcasses were fabricated according to the procedure of Welling ton (1933). Those cuts deemed most logical for use as ground beef were separated into bone and edible portion (lean and fat). Each cut was ground and a representative sample retained for fat determination. All ground cuts from each carcass were then blended and a representative sam ple taken for total fat determination.
Mean yield grades, live weights, carcass weights, marbling, and percentage fat of the blended samples were: 1.6, 313 kg, 161 kg, PD65, and 12.01% for the group slaughtered at the end of grazing; 1.8, 370 kg, 197 kg, Tr67, and 18.31% for 28 days on feed; 1.9, 402 kg, 211 kg, SL93, and 22.08% for 56 days on feed; 2.6, 455 kg, 245 kg, SM79 and 25.08% for 24 84 days on feed; 2.8, 479 kg, 267 kg, MT24, and 28.91% for 112 days on feed; and 2.7, 479 kg, 285 kg, MT59, and 32.65% for 140 days on feed.
These data, collected from yearling Angus steers, suggest that acceptable quality and yield grades and an acceptable fat percentage of the ground beef can be obtained after 65 days of grain feeding.
Greene, Billy Bruce, "Fattening patterns in yearling steers serially slaughtered after grazing spring-summer cool season grass pasture. " Master's Thesis, University of Tennessee, 1982.