Reverter A, Johnston D J, Graser H U, Wolcott M L, Upton W H
Animal Genetics Unit, Co-operative Research Centre for the Cattle and Beef Industry, The University of New England, Armidale, NSW, Australia.
J Anim Sci. 2000 Jul;78(7):1786-95. doi: 10.2527/2000.7871786x.
In order to estimate genetic parameters, abattoir carcass data on 1,713 Angus and 1,007 Hereford steers and heifers were combined with yearling live-animal ultrasound measurements on 8,196 Angus and 3,405 Hereford individuals from seedstock herds. Abattoir measures included carcass weight (CWT), percentage of retail beefyield (RBY), near-infrared measured intramuscular fat percentage (CIMF), preslaughter scanned eye muscle area (CEMA), and subcutaneous fat depth at the 12th rib (CRIB) and at the P8 site (CP8). Ultrasound scans on yearling animals included 12th-rib fat depth (SRIB), rump fat depth at the P8 site (SP8), eye muscle area (SEMA), and percentage of intramuscular fat (SIMF). Records on CWT were adjusted to 650-d slaughter age, and the remaining abattoir traits were adjusted to 300-kg CWT. Scan data were analyzed treating records on males and females as different traits. Multivariate analyses were performed on a variety of trait combinations using animal model and REML algorithm. Heritability (h2) estimates for CWT, RBY, CIMF, CP8, CRIB, and CEMA were .31, .68, .43, .44, .28, and .26, respectively, for Angus and .54, .36, .36, .08, .27, .38, respectively, for Hereford. Pooled across sexes, h2 estimates for SIMF, SP8, SRIB, and SEMA were .33, .55, .51, and .42, respectively, for Angus and .20, .31, .18, and .38, respectively, for Hereford. Genetic correlations (r(g)) between the same pair of carcass traits measured at yearling through scanning and directly at the abattoir were moderate to strongly positive, suggesting that selection using yearling ultrasound measurements of seedstock cattle should result in predictable genetic improvement for abattoir carcass characteristics. Estimates of r(g) between the scanned fat measurements and RBY were negative, ranging from -.85 for Angus heifers to -.05 for Hereford heifers. Also, the estimates of r(g) between SEMA and the fat records measured at the abattoir were negative and ranged from -.94 in Hereford heifers to -.02 in Angus heifers.
为了估计遗传参数，将1713头安格斯牛和1007头赫里福德阉牛及小母牛的屠宰场胴体数据，与来自种畜群的8196头安格斯牛和3405头赫里福德牛一岁龄活体动物超声测量数据相结合。屠宰场测量指标包括胴体重（CWT）、零售牛肉产量百分比（RBY）、近红外测量的肌内脂肪百分比（CIMF）、屠宰前扫描的眼肌面积（CEMA），以及第12肋处（CRIB）和P8部位（CP8）的皮下脂肪深度。一岁龄动物的超声扫描指标包括第12肋脂肪深度（SRIB）、P8部位的臀部脂肪深度（SP8）、眼肌面积（SEMA）和肌内脂肪百分比（SIMF）。CWT记录被调整到650天的屠宰年龄，其余屠宰场性状被调整到300千克的胴体重。扫描数据的分析将公母记录视为不同性状进行处理。使用动物模型和REML算法对各种性状组合进行了多变量分析。安格斯牛的CWT、RBY、CIMF、CP8、CRIB和CEMA的遗传力（h2）估计值分别为0.31、0.68、0.43、0.44、0.28和0.26，赫里福德牛的分别为0.54、0.36、0.36、0.08、0.27和0.38。综合两性来看，安格斯牛的SIMF、SP8、SRIB和SEMA的h2估计值分别为0.33、0.55、0.51和0.42，赫里福德牛的分别为0.20、0.31、0.18和0.38。一岁龄时通过扫描测量与直接在屠宰场测量的同一对胴体性状之间的遗传相关性（r(g)）为中度到强正相关，这表明使用种畜牛一岁龄超声测量进行选择应能带来可预测的屠宰场胴体特征遗传改良。扫描脂肪测量值与RBY之间的r(g)估计值为负，范围从安格斯小母牛的-0.85到赫里福德小母牛的-0.05。此外，SEMA与屠宰场测量的脂肪记录之间的r(g)估计值为负，范围从赫里福德小母牛的-0.94到安格斯小母牛的-
