Jenkins T G, Leymaster K A, MacNeil M D
Roman L Hruska U.S. Meat Animal Research Center, ARS, USDA, Clay Center, NE 68933, USA.
J Anim Sci. 1995 Dec;73(12):3627-32. doi: 10.2527/1995.73123627x.
Regression equations to predict kilograms of fat-free soft tissue (the sum of water and protein from chemical analyses) were developed from data collected on 526 steers and heifers. Straightbred animals representing Angus, Braunvieh, Charolais, Gelbvieh, Hereford, Limousin, Pinzgauer, Red Poll, and Simmental breeds of cattle contributed to the data set. Cattle ranged in slaughter weight and age from approximately 350 to 575 kg and from 13 to 23 mo, respectively. Diets (100% ground alfalfa, 67% ground alfalfa and 33% ground corn or 33% ground alfalfa and 67% ground corn) were cross-classified with breed and sex. Estimative traits included in the equation were warm carcass weight, fat depth at the 12th rib, and body impedance. Carcass soft-tissue samples were taken for determination of chemical constituents. The prediction equation accounted for 94% of the variation in fat-free soft tissue of the carcass. Adjusting for breed-sex-diet contemporary groups increased the R2 value by 2% units. The prediction model was evaluated using data collected on 65 steers sired by Charolais or by Hereford bulls at the Ft Keogh Livestock and Range Research Laboratory (Miles City, MT). Postweaning feeding strategies and slaughter ages varied among these animals. Carcass weight, back fat depth, and resistive impedance measures were recorded. Carcass soft-tissue samples were taken for determination of chemical constituents. Values of estimator variables recorded at Ft. Keogh were used in the regression equation to predict fat-free soft tissue for each animal. The values for kilogram of fat-free soft tissue determined from chemical analysis were regressed on predicted fat-free soft tissue. the results indicate that fat-free soft tissue of carcasses can be accurately predicted using estimative traits that do not diminish carcass value.
利用收集到的526头公牛和母牛的数据，建立了预测无脂软组织（通过化学分析得出的水和蛋白质的总和）千克数的回归方程。代表安格斯、西门塔尔、夏洛来、海福特、利木赞、皮兹高尔、红白花、格尔布维、布劳恩维赫等品种的纯种动物为数据集提供了数据。牛的屠宰体重和年龄范围分别约为350至575千克和13至23月龄。日粮（100%苜蓿粉、67%苜蓿粉和33%玉米粉或33%苜蓿粉和67%玉米粉）与品种和性别进行交叉分类。方程中包含的估计性状有热胴体重、第12肋骨处的脂肪厚度和身体阻抗。采集胴体软组织样本以测定化学成分。预测方程解释了胴体无脂软组织变异的94%。对品种 - 性别 - 日粮当代组进行调整后，R2值提高了2个百分点。使用在Ft Keogh牲畜与草原研究实验室（蒙大拿州迈尔斯城）收集的65头由夏洛来公牛或海福特公牛所生公牛的数据对预测模型进行评估。这些动物断奶后的饲养策略和屠宰年龄各不相同。记录胴体重、背膘厚度和电阻抗测量值。采集胴体软组织样本以测定化学成分。将在Ft Keogh记录的估计变量值代入回归方程，以预测每头动物的无脂软组织。将通过化学分析确定的无脂软组织千克数的值与预测的无脂软组织进行回归分析。结果表明，使用不降低胴体价值的估计性状可以准确预测胴体的无脂软组织。
