J Anim Sci. 2017 Dec;95(12):5584-5596. doi: 10.2527/jas2017.1840.
This study was conducted to assess the body and empty body fat physical and chemical composition through biometric measurements (BM) as well as postmortem measurements taken in 40 F Angus × Nellore bulls and steers. The animals used were 12.5 ± 0.51 mo of age, with an average shrunk BW of 233 ± 23.5 and 238 ± 24.6 kg for bulls and steers, respectively. Animals were fed 60:40 ratio of corn silage to concentrate diets. Eight animals (4 bulls and 4 steers) were slaughtered at the beginning of the trial, and the remaining animals were randomly assigned to a 1 + 2 × 3 factorial arrangement (1 reference group, 2 sexes, and 3 slaughter weights). The remaining animals were slaughtered when the average BW of the group reached 380 ± 19.5 (6 bulls and 5 steers), 440 ± 19.2 (6 bulls and 5 steers), and 500 ± 19.5 kg (5 bulls and 5 steers). Before the slaughter, the animals were led through a squeeze chute in which BM were taken, including hook bone width (HBW), pin bone width, abdomen width (AW), body length (BL), rump height, height at the withers, pelvic girdle length (PGL), rib depth (RD), girth circumference (GC), rump depth, body diagonal length (BDL), and thorax width. Additionally, the following postmortem measurements were obtained: total body surface (TBS), body volume (BV), subcutaneous fat (SF), internal physical fat (InF), intermuscular fat, carcass physical fat (CF), empty body physically separable fat (EBF), carcass chemical fat (CFch), empty body chemical fat (EBFch), fat thickness in the 12th rib, and 9th to 11th rib section fat. The equations were developed using a stepwise procedure to select the variables that should enter into the model. The and root mean square error (RMSE) were used to account for precision and accuracy. The ranges for and RMSE were 0.852 to 0.946 and 0.0625 to 0.103 m, respectively for TBS; 0.942 to 0.998 and 0.004 to 0.022 m, respectively, for BV; 0.767 to 0.967 and 2.70 to 3.24 kg, respectively, for SF; 0.816 to 0.900 and 3.04 to 4.12 kg, respectively, for InF; 0.830 to 0.988 and 3.44 to 8.39 kg, respectively, for CF; 0.861 to 0.998 and 1.51 to 10.98 kg, respectively, for EBF; 0.825 to 0.985 and 5.96 to 8.46 kg, respectively, for CFch; and 0.862 to 0.992 and 5.54 to 12.19 kg, respectively, for EBFch. Our results indicated that BM that could accurately and precisely be used as alternatives to predict different fat depots of F Angus × Nellore bulls and steers are AW, GC, or PGL for CF estimation; HBW and RD for CFch estimation; and body lengths such as BL and BDL for InF and SF estimation, respectively.
本研究旨在通过生物计量测量（BM）以及在 40 头安格斯 × 内罗尔公牛和阉牛的死后测量评估身体和空体脂肪的物理和化学成分。所用动物的年龄为 12.5±0.51 月龄，平均去势活重分别为 233±23.5kg 和 238±24.6kg。动物饲喂玉米青贮料与浓缩饲料的比例为 60:40。在试验开始时，8 头动物（4 头公牛和 4 头阉牛）被屠宰，其余动物随机分为 1+2×3 析因设计（1 个参考组、2 个性别和 3 个屠宰体重）。当组平均活重达到 380±19.5kg（6 头公牛和 5 头阉牛）、440±19.2kg（6 头公牛和 5 头阉牛）和 500±19.5kg（5 头公牛和 5 头阉牛）时，其余动物被屠宰。在屠宰前，动物被引导通过一个挤奶槽，在那里进行 BM 测量，包括钩骨宽度（HBW）、针骨宽度、腹部宽度（AW）、体长（BL）、臀部高度、肩高、骨盆带长度（PGL）、肋骨深度（RD）、胸围周长（GC）、臀部深度、体对角线长度（BDL）和胸腔宽度。此外，还获得了以下死后测量值：总体表（TBS）、体体积（BV）、皮下脂肪（SF）、内部物理脂肪（InF）、肌肉间脂肪、胴体物理脂肪（CF）、空体物理可分离脂肪（EBF）、胴体化学脂肪（CFch）、空体化学脂肪（EBFch）、第 12 肋骨脂肪厚度和第 9-11 肋骨段脂肪。使用逐步程序开发了方程，以选择应进入模型的变量。和均方根误差（RMSE）用于说明精度和准确性。TBS 的和 RMSE 范围分别为 0.852 至 0.946 和 0.0625 至 0.103m；BV 的和 RMSE 范围分别为 0.942 至 0.998 和 0.004 至 0.022m；SF 的和 RMSE 范围分别为 0.767 至 0.967 和 2.70 至 3.24kg；InF 的和 RMSE 范围分别为 0.816 至 0.900 和 3.04 至 4.12kg；CF 的和 RMSE 范围分别为 0.830 至 0.988 和 3.44 至 8.39kg；EBF 的和 RMSE 范围分别为 0.861 至 0.998 和 1.51 至 10.98kg；CFch 的和 RMSE 范围分别为 0.825 至 0.985 和 5.96 至 8.46kg；EBFch 的和 RMSE 范围分别为 0.862 至 0.992 和 5.54 至 12.19kg。我们的结果表明，AW、GC 或 PGL 可用于准确和精确地估计 CF；HBW 和 RD 可用于估计 CFch；BL 和 BDL 等体长度可用于分别估计 InF 和 SF。
