Beef originates from the progeny of either dairy or beef dams. The objective of the present study was to identify contributing factors to the differences in the carcass merit of progeny from both dam types. This goal was achieved using slaughter records from 16,414 bucket-reared dairy animals (DXD), 5,407 bucket-reared dairy-beef animals (BXD), 42,102 suckle-reared animals from a beef × dairy F1 cross dam (BXF1), and 93,737 suckle-reared animals from a beef × beef cow (BXB). Linear mixed models were used to quantify the least squares means for carcass characteristics in the various progeny genotypes. Nuisance fixed effects adjusted for in the models were: animal heterosis and recombination loss, dam parity, age at slaughter, and contemporary group; age at slaughter was replaced as an independent variable with both carcass weight and carcass fat score where the dependent variable was age at slaughter. In a follow-up analysis, models were re-analyzed where the genetic merit of the sire was adjusted for; a further analysis set the genetic merit of the dam for the dependent variable to be identical for both the dairy and beef dams. The final analysis adjusted to a common sire and dam genetic merit facilitating the estimation of just differences in early-life rearing strategies. Irrespective of the genetic merit of the sire and dam, animals originating from beef herds had heavier and more conformed carcasses. BXB animals had a 67 kg heavier carcass, with a conformation score (scale 1 [poor] to 15 [excellent]) of 5 units greater compared with DXD animals. When the genetic merit of all dams was set to be equal, BXB animals were heavier and better conformed than BXD animals. When the genetic merit for both the sire and dam were set to be equal, carcasses of the BXB animals were 15 kg heavier, with a 0.69 unit superior conformation score compared with the DXD animals; this difference is due to early life experiences. In conclusion, the majority of the inferiority in carcass metrics of calves from dairy herds compared with beef herds is due to differences in the genetic merit of the parents. Nevertheless, even after adjusting the parents to the same genetic merit, progeny from dairy herds were still inferior to their contemporaries born in beef herds, due most likely to the persistence of early life experiences.

中文翻译：

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肉牛的胴体和效率指标因小牛出生在奶牛场还是肉牛群而异

牛肉源自乳制品或牛肉坝的后代。本研究的目的是确定导致两种大坝类型后代胴体品质差异的影响因素。这一目标是通过使用来自 16,414 只桶养奶牛 (DXD)、5,407 只桶养奶牛肉动物 (BXD)、42,102 只来自牛肉 × 奶牛 F1 交叉坝 (BXF1) 的奶牛和 93,737 只奶牛的屠宰记录来实现的- 用牛肉 × 肉牛 (BXB) 饲养的动物。线性混合模型用于量化各种后代基因型中胴体特征的最小二乘均值。在模型中调整的滋扰固定效应是：动物杂种优势和重组损失、母猪胎次、屠宰年龄和当代群体；屠宰年龄被替换为屠体重量和屠体脂肪评分的自变量，其中因变量是屠宰年龄。在后续分析中，重新分析了模型，其中调整了公牛的遗传价值；进一步的分析将奶牛和牛肉大坝的因变量的遗传价值设定为相同。最终分析调整到共同的父系和母系遗传优点，有助于估计早期饲养策略的差异。不管父系和母系的遗传价值如何，源自牛群的动物的尸体更重、更合身。BXB 动物的尸体重 67 公斤，与 DXD 动物相比，其构象评分（1 [差] 到 15 [优秀]）高 5 个单位。当所有大坝的遗传价值设置为相等时，BXB 动物比 BXD 动物更重，更符合。当父系和母系的遗传价值相同时，BXB 动物的尸体重 15 公斤，与 DXD 动物相比，具有 0.69 单位的优越构象评分；这种差异是由于早年的生活经历造成的。总之，与肉牛群相比，奶牛群小牛的胴体指标的劣势主要是由于父母的遗传价值不同。尽管如此，即使将父母调整为相同的遗传价值，奶牛群的后代仍然不如他们同时代的肉牛群出生，这很可能是由于早期生活经历的持续存在。当父系和母系的遗传价值相等时，BXB 动物的尸体重 15 公斤，与 DXD 动物相比，具有 0.69 单位的优越构象评分；这种差异是由于早年的生活经历造成的。总之，与肉牛群相比，奶牛群小牛的胴体指标的劣势主要是由于父母的遗传价值不同。尽管如此，即使将父母调整为相同的遗传价值，奶牛群的后代仍然不如他们同时代的肉牛群出生，这很可能是由于早期生活经历的持续存在。当父系和母系的遗传价值相等时，BXB 动物的尸体重 15 公斤，与 DXD 动物相比，具有 0.69 单位的优越构象评分；这种差异是由于早年的生活经历造成的。总之，与肉牛群相比，奶牛群小牛的胴体指标的劣势主要是由于父母的遗传价值不同。尽管如此，即使将父母调整为相同的遗传价值，奶牛群的后代仍然不如他们同时代的肉牛群出生，这很可能是由于早期生活经历的持续存在。这种差异是由于早年的生活经历造成的。总之，与肉牛群相比，奶牛群小牛的胴体指标的劣势主要是由于父母的遗传价值不同。尽管如此，即使将父母调整为相同的遗传价值，奶牛群的后代仍然不如他们同时代的肉牛群出生，这很可能是由于早期生活经历的持续存在。这种差异是由于早年的生活经历造成的。总之，与肉牛群相比，奶牛群小牛的胴体指标的劣势主要是由于父母的遗传价值不同。尽管如此，即使将父母调整为相同的遗传价值，奶牛群的后代仍然不如他们同时代的肉牛群出生，这很可能是由于早期生活经历的持续存在。