DiCostanzo A, Meiske J C, Plegge S D
University of Minnesota, St. Paul 55108.
J Anim Sci. 1991 Apr;69(4):1337-48. doi: 10.2527/1991.6941337x.
Dry matter intake and BW data from 14 mature, nonpregnant, nonlactating Angus cows that were individually fed through two consecutive 70- to 80-d periods (maintenance and ad libitum) were used to predict ADG (ADG = -.512 + .213 DMI - .0017 BW, R2 = .95). This equation then was used to identify feed efficiency types among these cows. Cows were identified as average type (A) if ADG was within one SE of predicted ADG, and as efficient (E) or inefficient types (I) if ADG exceeded one SE above or below, respectively, its predicted ADG. Four, four, and six cows were identified and grouped as I, A, and E types, respectively. During the maintenance period, DM and ME intake and ADG were similar (P greater than .10) across all three efficiency types. But during the ad libitum period, voluntary DM and ME intakes of I cows were greater (P less than .05) than those of A or E cows. Average daily gains of I cows during ad libitum feeding were greater (P less than .10) than those of A cows. Daily ME required for maintenance of I cows was highest, that of A cows was intermediate, and that of E cows was lowest (180.2, 154.6, and 135.1 kcal/kg BW.75, respectively). Inefficient cows tended (P greater than .10) to have less fat and deposited more protein (P less than .05) than A and E cows (137.9 vs 77.2 and 46.2 protein g/d, respectively). Concurrent with higher protein accretion rates, liver weights of I cows were heavier (P less than .05) than those of A and E cows (8.58 vs 7.79 and 7.68 kg, respectively). Inefficient cows were characterized by higher energy requirements for maintenance. Their high protein accretion may partially explain their higher maintenance requirements.
利用14头成熟、非妊娠、非泌乳的安格斯母牛在连续两个70至80天的时期（维持期和自由采食期）单独饲养时的干物质采食量和体重数据来预测平均日增重（ADG）（ADG = -0.512 + 0.213 DMI - 0.0017 BW，R2 = 0.95）。然后用这个方程来确定这些母牛中的饲料效率类型。如果ADG在预测ADG的一个标准误范围内，则母牛被确定为平均型（A）；如果ADG分别超过或低于预测ADG一个标准误以上，则被确定为高效型（E）或低效型（I）。分别有4头、4头和6头母牛被确定并归类为I型、A 型和E型。在维持期，所有三种效率类型的干物质和代谢能摄入量以及平均日增重相似（P大于0.10）。但在自由采食期，I型母牛的自愿干物质和代谢能摄入量高于（P小于0.05）A型或E型母牛。自由采食期间I型母牛的平均日增重高于（P小于0.10）A型母牛。维持I型母牛每天所需的代谢能最高，A型母牛居中，E型母牛最低（分别为180.2、154.6和135.1千卡/千克体重0.75）。低效母牛的脂肪含量往往（P大于0.10）比A型和E型母牛少，蛋白质沉积更多（P小于0.05）（分别为137.9克/天与77.2克/天和46.2克/天的蛋白质）。与较高的蛋白质沉积率同时，I型母牛的肝脏重量比A型和E型母牛重（P小于0.05）（分别为8.58千克与7.79千克和7.68千克）。低效母牛的特点是维持所需的能量需求较高。它们较高的蛋白质沉积可能部分解释了它们较高的维持需求。
