Effect of postweaning growth and bulls selected for extremes in retail beef yield and intramuscular fat on progeny liveweight and carcass traits

Abstract

Abstract. The present study is a component of a multi-site experiment, using Bos taurus cattle generated at four locations across southern Australia, designed to examine postweaning growth pathways for progeny whose sires were extreme in retail beef yield and intramuscular fat. Treatment and interaction effects on beef production and meat quality were examined within and across sites. The present paper describes the effect of postweaning growth and sire carcass type on liveweight and carcass traits at the Hamilton site. Angus sires selected on estimated breeding values for extremes in retail beef yield (RBY%), intramuscular fat (IMF%) (estimated breeding values for IMF% are derived by using live-animal ultrasound scanning) or both and sire breed types considered to be more extreme in those traits (Limousin, and Belgian Blue for yield, and Wagyu for intramuscular fat) were joined to crossbred and straight-bred cows. After weaning, the resultant 645 steer and heifer progeny were grown on a fast and slow growth path to~550 kg and slaughtered, averaging 0.68 kg/day and 22.2 months, and 0.49 kg/day and 27.8 months for growth rate and age at slaughter, respectively. Growth path, sire carcass type and sex affected carcass traits; however, there were no sire carcass type by growth treatment interactions. The fast growth-path cattle were fatter, had more intramuscular fat (measured chemically), a higher Meat Standards of Australia (MSA) USA and AUS marble score, and a higher predicted MSA eating-quality score. Progeny of Wagyu sires were lighter at weaning and slaughter and had a lower hot standard carcass weight than the other sire carcass types. The Belgian Blue and Limousin progeny had a higher dressing percentage, a higher RBY% and a lower P8 and rib-fat depth and lower IMF% than the other sire breed types. Progeny of the high RBY% Angus had a lower rib-fat depth, a lower IMF% and higher RBY% than those selected for high IMF%. There was no difference in IMF% between the Wagyu or the high IMF% Angus. Progeny from the Belgian Blue, Limousin and Wagyu had a larger eye muscle area than the other sire breeds. The results indicate that simultaneous selection for supposedly antagonistic traits of IMF% and RBY% would result in carcass having high values of both measurements. Females were lighter than steers at slaughter, had a lower hot standard carcass weight, were fatter at the P8 and rib, and had a higher marble score and IMF%, a lower yield and a lower MSA-predicted eating-quality score than did steers. There was no interaction between postweaning growth and sire carcass type. These results indicate that with the use of appropriate sire carcass types and BREEDPLAN, and post-weaning nutrition, beef producers can confidently change carcass parameters to suit market specifications.Additional keywords: sire breed type.

Performance of steer progeny of sires differing in genetic potential for fatness and meat yield following post-weaning growth at different rates. 1. Growth and live-animal composition

“…Effects on fatness are of obvious practical importance to meeting carcass specifications when targeting specific market end points. The findings here of greater fatness associated with faster growth are consistent with the results reported by Graham et al (2009) from the Victorian site of the Regional Combination experiment, and by McIntyre et al (2009) from the Western Australian site. Graham et al (2009) also cited further supporting evidence from previous studies, showing higher planes of nutrition resulting in increased proportions of fat in the carcass (Berg and Butterfield 1968;Coleman et al 1993).…”

“…The findings here of greater fatness associated with faster growth are consistent with the results reported by Graham et al (2009) from the Victorian site of the Regional Combination experiment, and by McIntyre et al (2009) from the Western Australian site. Graham et al (2009) also cited further supporting evidence from previous studies, showing higher planes of nutrition resulting in increased proportions of fat in the carcass (Berg and Butterfield 1968;Coleman et al 1993). Robinson et al (2001) demonstrated a small effect on the finishing growth rate in favour of animals having slower growth during backgrounding and a tendency for those with higher backgrounding growth rates to have higher intramuscular fat levels.…”

“…In the present paper, we report the effects on live-animal performance during backgrounding and finishing for the NSW site. Results from the other sites (Victoria and Western Australia) are reported in associated papers (Graham et al 2009;McIntyre et al 2009). …”

Effects of growth path, sire type, calving time and sex on growth and carcass characteristics of beef cattle in the agricultural area of Western Australia

“…Although there were no significant differences, RBY-sired animals tended to have higher EMA than IMFsired animals and this could account for the remaining difference in yield estimated using the VIAscan. These results were consistent with those of Graham et al (2009) andWilkins et al (2009) who also found differences in VIAscan estimates of RBY-and IMF-sired animals. As in the present study, RBYsired animals tended to have lower fat thickness and larger EMA.…”

“…comm. ) and Graham et al (2009) found similar differences in the palatability score estimated from the MSA model. The striploin of animals in the study of Wilkins et al (2009) were also subjected to the MSA sensory taste panel.…”