Brown A H, Chewning J J, Johnson Z B, Loe W C, Brown C J
Dept. of Anim. and Poult. Sci., University of Arkansas, Fayetteville 72701.
J Anim Sci. 1991 Feb;69(2):451-61. doi: 10.2527/1991.692451x.
Changes in performance traits in beef cattle over the last 30 yr necessitate the re-evaluation of central testing procedures to ensure that they are cost effective and appropriate for current test objectives. The objective of this study was to evaluate the potential for reducing the length of evaluation from 140 d to either 112 or 84 d. Data evaluated were postweaning feedlot performance test records (collected from 1977 to 1986) on 1,830 individually fed bulls. Bulls representing 13 breeds (n greater than 25 per breed) were evaluated in the University of Arkansas Cooperative Bull Tests at Fayetteville, Hope, and Monticello, Arkansas. Models were fit for ADG, daily feed intake (FI) and feed conversion (FCONV) from d 1 to d 140 (ADG1-140, FI1-140 and FCONV1-140, respectively) and from d 1 to d 112 (ADG1-112, F11-112 and FCONV1-112, respectively). Models fit for ADG1-140, FI1-140, and FCONV1-140 using information up to d 112 had R2 of .90, .99, .88, and .94, respectively, and using information up to d 84 had R2 of .82, .94, and .80, respectively. Spearman rank correlation coefficients (all P less than .0001) were .93 for ADG1-140 and ADG1-112, .93 for ADG1-112 and ADG1-84, .99 for FI1-140 and FI1-112, .91 for FCONV1-140 and FCONV1-112, and .90 for FCONV1-112 and FCONV1-84. These coefficients indicate that bulls ranked similarly for performance traits at 84, 112, and 140 d. If the primary objective of central station testing is to evaluate ADG during the linear phase of growth, and if testing procedures are those currently recommended by the Beef Improvement Federation, then feeding bulls beyond 112 d has no advantage because the information upon which selection decisions are made is similar at both 112 and 140 d.
在过去30年里，肉牛生产性能性状发生了变化，因此有必要重新评估中心测试程序，以确保其具有成本效益且适合当前的测试目标。本研究的目的是评估将评估期从140天缩短至112天或84天的可能性。所评估的数据是1977年至1986年期间对1830头个体饲养公牛的断奶后育肥场性能测试记录。在阿肯色大学位于费耶特维尔、霍普和蒙蒂塞洛的合作公牛测试中，对代表13个品种（每个品种n大于25）的公牛进行了评估。建立了从第1天到第140天（分别为ADG1 - 140、FI1 - 140和FCONV1 - 140）以及从第1天到第112天（分别为ADG1 - 112、F11 - 112和FCONV1 - 112）的平均日增重（ADG）、日采食量（FI）和饲料转化率（FCONV）的模型。使用截至第112天的信息建立的ADG1 - 140、FI1 - 140和FCONV1 - 140模型的R²分别为0.90、0.99、0.88和0.94，使用截至第84天的信息建立的模型的R²分别为0.82、0.94和0.80。Spearman等级相关系数（所有P值均小于0.0001）：ADG1 - 140与ADG1 - 112为0.93，ADG1 - 112与ADG1 - 84为0.93，FI1 - 140与FI1 - 112为0.99，FCONV1 - 140与FCONV1 - 112为0.91，FCONV1 - 112与FCONV1 - 84为0.90。这些系数表明，在84天、112天和14天时，公牛在生产性能性状方面的排名相似。如果中心站测试的主要目标是评估生长线性阶段的ADG，并且测试程序是牛肉改良联合会目前推荐的程序，那么在112天后继续饲养公牛没有优势，因为在112天和140天做出选择决策所依据的信息是相似的。
