Addis Addisu Hailu, Blair Hugh Thomas, Morris Stephen Todd, Kenyon Paul Richard, Schreurs Nicola Maria
Animal Science, School of Agriculture and Environment, Massey University, Palmerston North 4442, New Zealand.
Animals (Basel). 2020 Apr 9;10(4):651. doi: 10.3390/ani10040651.
Prediction equations have been widely utilized for carcass classification and grading systems in older beef cattle. However, the equations are mostly relevant for common beef breeds and 18 to 24 month old animals; there are no equations suitable for yearling, dairy-origin cattle. Therefore, this study developed prediction models using 60 dairy-origin, 8 to 12 month old steers to indicate saleable meat yield from hind-legs, which would assist with carcass classification and grading. Fat depth over the rump, rib fat depth, and eye muscle area between the 12th and 13th ribs were measured using ultrasound, and wither height was recorded one week prior to slaughter. The muscles from the hind-leg were retrieved 24 h after slaughter. Prediction equations were modeled for the hind-leg muscles weight using carcass weight, wither height, eye muscle area, rump, and rib fat depths as predictors. Carcass weight explained 61.5% of the variation in hind-leg muscles weight, and eye muscle area explained 39.9% ( < 0.05). Their combination in multivariate analysis explained 63.5% of the variation in hind-leg muscles weight. The R of the prediction in univariate and multivariate analyses was improved when data were analyzed per age group. Additional explanatory traits for yearling steers, including body length, hearth girth, and muscle depth and dimensions measured using video image analysis scanning (VIAscan), could improve the prediction ability of saleable meat yield from yearling dairy beef steers across the slaughter age groups.
预测方程已广泛应用于老龄肉牛的胴体分类和分级系统。然而，这些方程大多适用于常见的肉牛品种以及18至24月龄的动物；目前尚无适用于一岁龄、乳用品种牛的方程。因此，本研究利用60头8至12月龄的乳用品种阉牛建立了预测模型，以预测后腿可售肉产量，这将有助于胴体分类和分级。使用超声测量臀部脂肪深度、肋部脂肪深度以及第12和13肋骨之间的眼肌面积，并在屠宰前一周记录体高。屠宰后24小时取出后腿肌肉。以胴体重、体高、眼肌面积、臀部和肋部脂肪深度作为预测因子，建立了后腿肌肉重量的预测方程。胴体重解释了后腿肌肉重量变异的61.5%，眼肌面积解释了39.9%（P<0.05）。在多变量分析中，它们的组合解释了后腿肌肉重量变异的63.5%。按年龄组分析数据时，单变量和多变量分析中预测的R值有所提高。一岁龄阉牛的其他解释性性状，包括体长、胸围以及使用视频图像分析扫描（VIAscan）测量的肌肉深度和尺寸，可提高一岁龄乳用肉牛阉牛在整个屠宰年龄组的可售肉产量预测能力。
