Turner J W, Pelton L S, Cross H R
Dept. of Anim. Sci., Texas A&M Univ., College Station 77843-2471.
J Anim Sci. 1990 Nov;68(11):3502-6. doi: 10.2527/1990.68113502x.
Ultrasonic measurements of fat thickness (FAT) and ribeye area (REA) were analyzed together with weight (WT), scrotal circumference (SC) and age data from 385 yearling Hereford bulls representing 45 sires. Additional variables created were 100*REA/WT (REACWT) and 365-d adjusted REA (AREA). Multiplicative age adjustment for AREA was calculated from linear regression of REA on age. Heritabilities were .45 +/- .17 for REACWT, .36 +/- .16 for WT, .12 +/- .13 for REA, .11 +/- .13 for AREA, .04 +/- .13 for FAT and .18 +/- .14 for SC. Phenotypic and genetic correlations were strongly negative for WT with REACWT. Neither AREA nor REACWT alone were considered suitable muscling variables due to their association with age, WT and FAT. Ultrasound REA measurements should be adjusted for the linear effects of age and WT and quadratic effects of FAT before being used for selection. Measurement of SC indicated a strong association with WT (r = .55) and a moderate positive genetic correlation with REA (.49 +/- .58).
对385头一岁龄赫里福德公牛的脂肪厚度（FAT）、肋眼面积（REA）进行了超声测量，并分析了其体重（WT）、阴囊周长（SC）和年龄数据，这些公牛代表了45个父系。创建的其他变量包括100×REA/WT（REACWT）和365天调整后的REA（AREA）。AREA的乘法年龄调整是根据REA与年龄的线性回归计算得出的。REACWT的遗传力为0.45±0.17，WT为0.36±0.16，REA为0.12±0.13，AREA为0.11±0.13，FAT为0.04±0.13，SC为0.18±0.14。WT与REACWT的表型和遗传相关性呈强负相关。由于AREA和REACWT与年龄、WT和FAT相关，单独使用它们都不被认为是合适的肌肉变量。在将超声REA测量值用于选择之前，应针对年龄和WT的线性效应以及FAT的二次效应进行调整。SC测量表明其与WT有很强的相关性（r = 0.55），与REA有中等程度的正遗传相关性（0.49±0.58）。
