Velazco J, Morrill J L, Grunewald K K
Department of Animal Sciences, Kansas State University, Manhattan 66506-1600, USA.
J Anim Sci. 1999 Jan;77(1):131-6. doi: 10.2527/1999.771131x.
The objective of this experiment was to study the usefulness of bioelectrical impedance analysis (BIA) in determining soft tissue composition (STC) and carcass fat-free mass (CFFM) of Holstein steers at different ages. Growth data and prediction of STC and CFFM were determined for four groups of Holstein steers: 12 of 3 mo, 12 of 6 mo, 15 of 9 mo, and 16 of 12 mo of age. Average weight for animals at 3, 6, 9, and 12 mo were 96.6, 204.7, 354.1, and 465.9 kg, respectively. Average fat content of carcass soft tissue at 3, 6, 9, and 12 mo were 2.6, 9.8, 18.2, and 24.6%, respectively. Average protein content of the carcass soft tissue was 20.7% at 3 mo, 20% at 6 mo, 18.30% at 9 mo, and 16.9% at 12 mo of age. Feed and water were withheld for 20 h before the BIA was applied. Steers were sedated and forced to recumbency in a lateral position on their right sides over a nonconductive surface. Two electrodes were placed on each limb of the right side (metatarsal and metacarpal regions on back and front foot, respectively). Resistance (Rs) and reactance (Xc) were obtained by attaching four terminals to the electrodes. Impedance and other predictors such as Vol1 (L/Rs), Vol2 (L2/(RS2+Xc2).5, Vol3 (geometrical animal volume), L (2 x height + body length), and L2 were calculated from Rs and Xc, and body measurements and were used to generate prediction equations for CFFM and carcass soft tissue composition. Carcass fat-free mass was predicted accurately for all age groups and the pooled data (r2 = .99 at 3 mo, .99 at 6 mo, .97 at 9 mo, .77 at 12 mo, and .98 for the pooled data). Correlation coefficients between impedance readings and CFFM and carcass composition were calculated. Carcass CFFM and kilograms of H2O for the pooled data (across age groups) were both correlated highly to Vol1 (.97), Vol2 (.95), L (.97), and L2 (.97).
本实验的目的是研究生物电阻抗分析（BIA）在测定不同年龄荷斯坦公牛的软组织成分（STC）和胴体去脂体重（CFFM）方面的实用性。测定了四组荷斯坦公牛的生长数据以及STC和CFFM的预测值：3月龄12头、6月龄12头、9月龄15头、12月龄16头。3、6、9和12月龄动物的平均体重分别为96.6、204.7、354.1和465.9千克。3、6、9和12月龄胴体软组织的平均脂肪含量分别为2.6%、9.8%、18.2%和24.6%。胴体软组织的平均蛋白质含量在3月龄时为20.7%，6月龄时为20%，9月龄时为18.30%，12月龄时为16.9%。在进行BIA之前，禁食禁水20小时。给公牛注射镇静剂，并使其右侧卧在非导电表面上。在右侧的每个肢体上放置两个电极（分别位于后脚和前脚的跖骨和掌骨区域）。通过将四个端子连接到电极上获得电阻（Rs）和电抗（Xc）。根据Rs和Xc以及身体测量数据计算阻抗和其他预测指标，如Vol1（L/Rs）、Vol2（L2/(RS2+Xc2).5）、Vol3（几何动物体积）、L（2×身高+体长）和L2，并用于生成CFFM和胴体软组织成分的预测方程。对所有年龄组和汇总数据（3月龄时r2 = 0.99，6月龄时r2 = 0.99，9月龄时r2 = 0.97，12月龄时r2 = 0.77，汇总数据时r2 = 0.98）都准确预测了胴体去脂体重。计算了阻抗读数与CFFM和胴体成分之间的相关系数。汇总数据（跨年龄组）的胴体CFFM和H2O千克数与Vol1（0.97）、Vol2（0.95）、L（0.97）和L2（0.97）都高度相关。
