Genetic effects on carcass quantity, quality, and palatability traits in straightbred and crossbred Romosinuano steers.
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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 cm(2)/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 cm(2)/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.