IDENTIFICATION AND UTILIZATION OF MECHANISMS RESPONSIBLE FOR THE ADAPTATION OF CATTLE TO STRESSORS OF THE SUBTROPICS
Title: Genetic effects on carcass quantity, quality, and palatability traits in straightbred and crossbred Romosinuano steers
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 4, 2012
Publication Date: July 1, 2012
Citation: Riley, D.G., Chase, C.C., Jr., Coleman, S.W., Phillips, W.A., Miller, M.F., Brooks, J., Johnson, D.D., Olson, T.A. 2012. Genetic effects on carcass quantity, quality, and palatability traits in straightbred and crossbred Romosinuano steers. Journal of Animal Science. 90:2159-2166.
Interpretive Summary: Brahman crossbred cows are adapted, superior performers, and are widely sought and used by cow-calf producers in the Southern U.S., primarily due to their environmental adaption. The steer half-siblings to these females are often sent to the Great Plains for backgrounding, feeding, and harvest. The reputation for inadequate carcass quality and tenderness for both Brahman purebreds and crossbreds results in lower prices paid for calves with visible Brahman inheritance. Other cattle of the world are adapted to the conditions of the tropics and subtropics; these include the Bos taurus Criollo breeds of South America, including the Romosinuano. Investigators at the Subtropical Agricultural Research Station in Brooksville, Florida, evaluated performance of the Romosinuano as straightbreds and crossbreds in all stages of beef production. In addition to Romosinuano, this evaluation also included Angus and Brahman straightbreds and crossbreds. For this study, after weaning, all female calves were retained for further evaluation and steer calves were transported to the Grazinglands Research Laboratory in El Reno, OK, where they were backgrounded on wheat pasture for 6 months and then fed a finishing diet for an average of 130 days until harvest. Hybrid vigor or heterosis was significant for hot carcass weight, dressing percent, ribeye area and yield grade, but not marbling. Generally, heterosis estimates were smallest for Romosinuano-Angus, intermediate for Romosinuano-Brahman, and largest for Brahman-Angus. Romosinuano sires decreased carcass quantity traits, but increased loin muscle area per 100 kg hot carcass weight. Brahman sires increased carcass quantity traits, but decreased loin muscle area per 100 kg hot carcass weight. Angus sires increased 12th rib fat thickness. Among sire breed means, Romosinuano had reduced marbling score than Angus, but greater mean sensory tenderness scores and reduced percentage Standard carcasses than Brahman. Whereas, Angus sire breed means for marbling score, overall tenderness, and percentage Choice carcasses were greater than Brahman. Romosinuano steer carcasses have some quality and palatability advantages relative to Brahman carcasses; however, reduced final body weight and carcass weight may negate the advantages. Like the Brahman, use of Romosinuano in the U.S. will be as crossbred cows. Thus, reproduction and longevity of Romosinuano crossbred cows would appear to be most critical for those making breeding decisions.
The objectives of this work were to estimate heterosis and breed genetic effects for carcass quantity, quality, and palatability traits of steers (Bos spp.) produced from matings of Romosinuano, Brahman, and Angus cattle. Steers (n = 464) were weaned at 7 mo of age and transported to the Southern Great Plains where they grazed winter wheat for 6 mo and were then fed a finishing diet until serial slaughter after different days on feed (average 130 d). Carcass quality and quantity traits were measured; steaks (aged 7 d) were obtained for palatability evaluation. Heterosis was detected for BW, HCW, dressing percentage, LM area, and yield grade for all pairs of breeds. Generally, Romosinuano-Angus heterosis estimates were smallest, Romosinuano-Brahman estimates were intermediate, and Brahman-Angus heterosis estimates were largest. The direct Romosinuano effect was to decrease (P < 0.05) BW (–67 ± 16 kg), HCW (–48 ± 10 kg), dressing percentage (–1.4 ± 0.5 units), 12th rib fat thickness (–5.2 ± 0.8 mm), and yield grade (–0.9 ± 0.1), and to increase LM area per 100 kg HCW (3.6 ±
0.3 cm2/100 kg). Significant Brahman direct effects were detected for BW (34 ± 17 kg), HCW (29 ± 10 kg), dressing percentage (1.6 ± 0.6 %), LM area per 100 kg HCW (–3.3 ± 0.4 cm2/100 kg), and yield grade (0.6 ± 0.1). Significant Angus direct effects were to increase 12th rib fat thickness (3.8 ± 1 mm). Among sire breed means, Romosinuano had reduced (P = 0.002) marbling score (393 ± 9) than Angus, but greater mean sensory tenderness scores (5.8 ± 0.1), and reduced percentage Standard carcasses (10 ± 2%) than Brahman (P < 0.002). Angus sire breed means for marbling score (475 ± 10), overall tenderness (5.8 ± 0.1), and percentage Choice carcasses (75 ± 5%) were greater (P < 0.05) than Brahman sire breed means (360 ± 11, 5.4 ± 0.1, 31 ± 5%). From consideration only of characteristics of the end product of beef production, Romosinuano did not provide a clearly superior alternative to Brahman for U.S. producers, as they had some quality and palatability advantages relative to Brahman, but at lighter HCW.