Herring W O, Miller D C, Bertrand J K, Benyshek L L
Animal and Dairy Sciences Department, Univ. of Georgia, Athens 30602-2771.
J Anim Sci. 1994 Sep;72(9):2216-26. doi: 10.2527/1994.7292216x.
Before slaughter, 44 Hereford-sired steers were measured ultrasonically for backfat (UFAT) and longissimus muscle area (ULMA) between the 12th and 13th ribs by three technicians (TECH) using two different machines (MACH) on two consecutive days (DAY). Each TECH interpreted (INT) his own images in addition to other TECH images. The absolute values of the difference between the 2 DAY's ultrasound measurements for ULMA (magnitude of LMAR) and UFAT (magnitude of FATR) were analyzed with a model including fixed effects of MACH and TECH with a random effect of steer and all interactions. For both magnitude of LMAR and magnitude of FATR, MACH x TECH was significant (P < .10). Correlations between the 2 DAY's measurements ranged from .36 to .90 and .69 to .90 for ULMA and UFAT, respectively. Simple statistics to quickly evaluate TECH and MACH were developed. Root mean squared errors (RMSE) and error standard deviations (ESD) between repeated measurements ranged from 3.89 to 11.32 and 3.93 to 11.34 cm2 for ULMA and .12 to .20 cm and .12 to .20 cm for UFAT, respectively. For accuracy, the absolute values of the difference between the ultrasound and carcass measurement for fat (magnitude of FATD) and longissimus muscle area (magnitude of LMAD) were analyzed with a model accounting for fixed effects of DAY, TECH, and MACH and a random effect of steer with all higher-order interactions. For magnitude of LMAD, TECH x MACH was a significant source of variation (P < .001). Also, a similar model was fit that included the fixed effects of TECH, MACH, and INT and a random effect of steer with all interactions. The MACH x INT interaction was found to be significant for magnitude of LMAD (P < .05). From this research, TECH and MACH differences do exist. Ultrasound is a valid means of measuring carcass traits in live steers if appropriate personnel and equipment are selected.
屠宰前，三名技术人员（TECH）使用两台不同的机器（MACH），在连续两天（DAY）内，对44头赫里福德种公牛的第12和13肋骨之间的背膘厚度（UFAT）和最长肌面积（ULMA）进行了超声测量。除了各自的图像外，每位技术人员还对其他技术人员的图像进行了解读（INT）。对ULMA（LMAR幅度）和UFAT（FATR幅度）两天超声测量值之间差异的绝对值进行分析，模型包括MACH和TECH的固定效应以及公牛的随机效应和所有交互作用。对于LMAR幅度和FATR幅度，MACH×TECH均具有显著意义（P < 0.10）。两天测量值之间的相关性，ULMA范围为0.36至0.90，UFAT范围为0.69至0.90。开发了用于快速评估TECH和MACH的简单统计方法。重复测量之间的均方根误差（RMSE）和误差标准差（ESD），ULMA分别为3.89至11.32和3.93至11.34平方厘米，UFAT分别为0.12至0.20厘米和0.12至0.20厘米。为了评估准确性，对脂肪（FATD幅度）和最长肌面积（LMAD幅度）的超声测量值与胴体测量值之间差异的绝对值进行分析，模型考虑了DAY、TECH和MACH的固定效应以及公牛的随机效应和所有高阶交互作用。对于LMAD幅度，TECH×MACH是一个显著的变异来源（P < 0.001）。此外，拟合了一个类似的模型，包括TECH、MACH和INT的固定效应以及公牛的随机效应和所有交互作用。发现MACH×INT交互作用对于LMAD幅度具有显著意义（P < 0.05）。从这项研究来看，TECH和MACH之间确实存在差异。如果选择了合适的人员和设备，超声是测量活牛胴体性状的有效方法。
