Genetic and environmental parameters for steer ultrasound and carcass traits1

Abstract

Carcass measurements for weight, longissimus muscle area, 12-13th-rib fat thickness, and marbling score, as well as for live animal measurements of weight at the time of ultrasound, ultrasound longissimus muscle area, ultrasound 12-13th-rib fat thickness, and ultrasound-predicted percentage ether extract were taken on 2,855 Angus steers. The average ages for steers at the time of ultrasound and at slaughter were 391 and 443 d, respectively. Genetic and environmental parameters were estimated for all eight traits in a multivariate animal model. In addition to a random animal effect, the model included a fixed effect for contemporary group and a covariate for measurement age. Heritabilities for carcass weight, carcass longissimus muscle area, carcass fat thickness, carcass marbling score, ultrasound weight, ultrasound longissimus muscle area, ultrasound fat thickness, and ultrasound-predicted percentage ether extract were 0.48, 0.45, 0.35, 0.42, 0.55, 0.29, 0.39, and 0.51, respectively. Genetic correlations between carcass and ultrasound longissimus muscle area, carcass and ultrasound fat thickness, carcass marbling score and ultrasound-predicted percentage ether extract, and carcass and ultrasound weight were 0.69, 0.82, 0.90, and 0.96, respectively. Additional estimates were derived from a six-trait multivariate animal model, which included all traits except those pertaining to weight. This model included a random animal effect, a fixed effect for contemporary group, as well as covariates for both measurement age and weight. Heritabilities for carcass longissimus muscle area, carcass fat thickness, carcass marbling score, ultrasound longissimus muscle area, ultrasound fat thickness, and ultrasound-predicted percentage ether extract were 0.36, 0.39, 0.40, 0.17, 0.38, and 0.49, respectively. Genetic correlations between carcass and ultrasound longissimus muscle area, carcass and ultrasound fat thickness, and carcass marbling and ultrasound-predicted percentage ether extract were 0.58, 0.86, and 0.94, respectively. The high, positive genetic correlations between carcass and the corresponding real-time ultrasound traits indicate that real-time ultrasound imaging is an alternative to carcass data collection in carcass progeny testing programs.

Efeitos de ambiente e estimativas de parâmetros genéticos para características de carcaça em bovinos da raça Canchim criados em pastagem

“…Diversos autores observaram valores superiores aos do presente estudo para as médias de AOL e inferiores para EGS (Turner et al, 1990;Arnold et al, 1991;Moser et al, 1998;Kemp et al, 2002) efeito mais pronunciado observado através do processo de engorda. Ainda segundo o mesmo autor, a taxa de acúmulo de gordura nos machos inteiros é menor do que nos novilhos, que por sua vez é menor do que nas novilhas.…”

Candidate gene region for control of rib eye area in Canchim beef cattle

“…Several authors, studying Hereford, Brangus, Angus, and Santa Gertrudis breeds, found higher values for REA and lower values for BFT (Turner et al, 1990;Arnold et al, 1991;Moser et al, 1998;Kemp et al, 2002) in animals with 320-369 days of age that were supplemented and mostly male. Values observed in these studies were between 47.46 and 86.0 cm 2 for REA and from 0.47 to 0.95 mm for BFT.…”

Padrão de deposição de tecidos protéicos e gordura em cordeiros abatidos precocemente e sua mensuração utilizando a ultra-sonografia

“…Aplicações principais da ultrasonografia em tempo real na ciência animal como metodologia de estimativa in vivo da composição da carcaça; 1) em programas de seleção de reprodutores para características de qualidade da carcaça e da carne (Brethour, 1992;Lo et al, 1992;Kemp et al, 2002; 2) manejo alimentar e treinamento de avaliação da condição corporal (Delfa et al,1991;Domecq et al,1995, bem como na validação da metodologia de avaliação da condição corporal (Schwager-Suter et al, 2000;Cadavez et al, 2002ª;Bueno et al, 2003; 3) na definição do ponto ótimo de abate (Kempster e Owen,1982;Fuller et al,1990 ;Houghton e Turlington, 1992;Stanford et al, 1998 GÊNOVA, L.G. e DUARTE, K.M.R.…”