Postweaning liveweights and carcass traits of Hereford, 1/4 Simmental-3/4 Hereford crossbreed, first-cross Simmental-Hereford, highgrade Simmental, and Belmont Red steers were compared from 3 cohorts bred at Brigalow Research Station, Theodore, Queensland. One half of each breed was grown and fattened at Brigalow Research Station, and the other half at a different site in southern Queensland, for each of 3 cohorts. When the mean liveweight of the Hereford steers reached 450 kg, a random selection of all breed groups was slaughtered (light group), while the remainder was slaughtered when the Hereford steers reached 550 kg liveweight (heavy group). Highgrade Simmental steers had higher (P<0.05) liveweights than 114 Simmentals and Herefords at each site in each year at all ages. While highgrade Simmentals were usually heavier than first-cross Simmental-Herefords and Belmont Reds, differences were not always significant. First-cross Simmental- Hereford and Belmont Red steers were usually heavier (P<0.05) than Herefords. Response to higher nutritional levels from provision of forage crop varied according to breed, with highgrade Simmentals showing the greatest liveweight response (268 kg by 27 months) and Belmont Reds the least (164 kg) over contemporaries grazing pasture only. Highgrade Sirnmental steers had the heaviest (P<0.05) carcasses in both slaughter groups (274 and 340 kg, respectively), and there were no significant (P>0.05) differences between Belmont Red and first-cross Simmental-Hereford steers (light group, 263 and 258 kg; heavy group, 318 and 327 kg). The 114 Simmental steers had heavier (P<0.05) carcasses than Hereford steers in both slaughter groups (light, 244 v. 235 kg; heavy, 307 v. 295 kg). Belmont Red carcasses had the greatest rib fat depth for both slaughter groups (6.6 and 8.4 mm), and highgrade Simmental carcasses were leanest (3.3 and 4.1 mm; P<0.05). Carcasses from 114 Simmental and from Hereford steers had similar rib fat depth in both slaughter groups (light, 5.0 and 5.1 mm; heavy, 6.8 and 6.8 mm), while the fat depths on first-cross Simmental-Hereford carcasses were 4.3 and 6.0 mm. Although highgrade Simmental steers yielded the heaviest carcasses, the lack of subcutaneous fat cover may reduce the value of these carcasses, on a unit weight basis. By contrast, Belmont Red carcasses were more likely to meet the range of market specifications for grass-fed carcasses.
Studies on Application of Ultrasound for Selection of Carcass Traits on Donor Cow for Embryo Transfer in Japanese Black Cattle
