Wall P B, Rouse G H, Wilson D E, Tait R G, Busby W D
Department of Animal Science, Iowa State University, Ames 50011, USA.
J Anim Sci. 2004 Jun;82(6):1621-9. doi: 10.2527/2004.8261621x.
Steers from research crossbreeding projects (n = 406) were serially scanned using real-time ultrasound at 35-d intervals from reimplant time until slaughter. Cattle were evaluated for rump fat depth, longissimus muscle area (ULMA), 12th-rib fat thickness (UFAT), and percentage of intramuscular fat (IMF) to determine the ability of ultrasound to predict carcass composition at extended periods before slaughter. Additional background information on the cattle, such as live weight, ADG, breed of sire, breed of dam, implant, and frame score was also used. Carcass data were collected by trained personnel at "chain speed," and samples of the 12th-rib LM were taken for ether extract analysis. Simple correlation coefficients showed positive relationships (P < 0.01) between ultrasound measures taken less than 7 d before slaughter and carcass measures: ULMA and carcass LM area (CLMA, r = 0.66); UFAT and carcass 12th-rib fat thickness (CFAT, r = 0.74); and IMF and carcass numeric marbling score (r = 0.61). The same correlation coefficients for ultrasound measures taken 96 to 105 d before slaughter and carcass values (P < 0.01) were 0.52, 0.58, and 0.63, respectively. Steers were divided into source-verified and nonsource-verified groups based on the level of background information for each individual. Regression equations were developed for the carcass measurements; 46% of the variation could be explained for CLMA and 44% of CFAT at reimplant time, 46% of the variation in quality grade and 42% of the variation in yield grade could be explained. Significant predictors of quality grade were IMF (P < 0.001), natural log of 12th-rib fat thickness (LUFAT, P < 0.001), and ADG (P < 0.01), whereas LUFAT (P < 0.001), ULMA (P < 0.01), live weight (P < 0.001), hip height (P < 0.001), and frame score (P < 0.001) were significant predictors of yield grade. Regressions using ultrasound data taken 61 to 69 d before slaughter showed increasing R2. Live ultrasound measures at reimplant time are a viable tool for making decisions regarding future carcass composition.
对研究杂交项目中的406头阉牛，从再植入时间到屠宰期间，每隔35天使用实时超声进行连续扫描。评估牛的臀脂深度、背最长肌面积（ULMA）、第12肋处脂肪厚度（UFAT）和肌内脂肪百分比（IMF），以确定超声在屠宰前较长时间预测胴体组成的能力。还使用了关于这些牛的其他背景信息，如活重、平均日增重、父本品种、母本品种、植入物和体型评分。胴体数据由训练有素的人员以“链速”收集，并采集第12肋处背最长肌样本进行乙醚提取物分析。简单相关系数表明，屠宰前不到7天的超声测量值与胴体测量值之间存在正相关关系（P < 0.01）：ULMA与胴体背最长肌面积（CLMA，r = 0.66）；UFAT与胴体第12肋处脂肪厚度（CFAT，r = 0.74）；以及IMF与胴体大理石花纹评分（r = 0.61）。屠宰前96至105天的超声测量值与胴体值的相同相关系数（P < 0.01）分别为0.52、0.58和0.63。根据每头牛的背景信息水平，将阉牛分为来源验证组和非来源验证组。建立了胴体测量的回归方程；再植入时，CLMA变异的46%和CFAT变异的44%可以得到解释，质量等级变异的46%和产量等级变异的42%可以得到解释。质量等级的显著预测指标是IMF（P < 0.001）、第12肋处脂肪厚度自然对数（LUFAT，P < 0.001）和平均日增重（P < 0.01），而LUFAT（P < 0.001）、ULMA（P < 0.01）、活重（P < 0.001）、臀高（P < 0.001）和体型评分（P < 0.001）是产量等级的显著预测指标。使用屠宰前61至69天的超声数据进行的回归显示R2增加。再植入时的实时超声测量是用于对未来胴体组成做出决策的可行工具。
