Doctor of Philosophy (PhD)
School of Animal Science
Feedlot and carcass data from 1,533 weanling steers consigned to the Louisiana Calf-to-Carcass program from 1992 to 1998 were used to evaluate the influence of feeder calf grade, sire breed, and initial feedlot weight on growth and carcass traits. Each October, spring born calves were delivered to Clinton, Ruston, or Lake Charles loadout sites. Steers were identified by sire breed, tagged, weighed, assigned a feeder calf grade. Forty-six, 18, 26, and 10 percent of the steers graded large frame-thick muscle, large frame-moderate muscle, medium frame-thick muscle, and medium frame-moderate muscle, respectively. Steers were trucked to a commercial feedlot and sorted into pen lots based on predicted harvest weight and grade. Steers were harvested at approximately 1 cm fat thickness. Steers were grouped by breed of sire origin into American (Beefmaster, Braford, Brahman, Brangus, Gelbray, Red Brangus, Simbrah), English (Angus, Hereford, Red Poll), and European (Braunvieh, Charolais, Gelbvieh, Limousin, Salers, Simmental) sire breed groups. Growth and carcass traits were analyzed with a linear mixed model that included year-location as random and feeder calf grade, sire breed group, and feeder calf grade x sire breed group as fixed sources of variation. Large frame steers had .05 ± .02 kg greater feedlot average daily gain, 21 ± 4 and 10 ± 3 kg heavier harvest and hot carcass weights, 3.3 ±.8 cm2 larger ribeye areas and lower yield and quality grades than medium frame steers (P <.01). Thick muscled steers were similar to moderate muscle steers for most traits. European-sired steers had larger ribeye area (P < .05), larger ribeye area per 100 kg of carcass (P < .05), lower yield grade (P < .05), and less fat thickness (P < .05) than English- and American-sired steers. English-sired steers had higher marbling score (P < .05) than American- and European-sired steers. Light weight steers had lower harvest weight (P < .05) and smaller ribeye area (P <.05) than moderate and heavy weight steers. Generally, large frame steers and European-sired steers produced higher yielding carcasses and medium frame steers and English-sired steers produced carcasses with higher quality grade.
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Devillier, James E., "The Louisiana Calf-to-Carcass program: growth and carcass traits" (2003). LSU Doctoral Dissertations. 3530.
D. E. Franke