Twomey Alan J, Ring Siobhán C, McHugh Noirin, Berry Donagh P
Animal and Grassland Research and Innovation Centre, Teagasc, Moorepark, Fermoy, Co. Cork, Ireland.
Irish Cattle Breeding Federation, Highfield House, Bandon, Co. Cork, Ireland.
J Anim Sci. 2020 Nov 1;98(11). doi: 10.1093/jas/skaa321.
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.
牛肉源自奶牛或肉牛母畜的后代。本研究的目的是确定导致这两种母畜类型后代胴体品质差异的影响因素。通过使用来自16414头桶饲奶牛（DXD）、5407头桶饲奶肉牛（BXD）、42102头来自肉牛×奶牛F1杂交母畜的吮乳饲养动物（BXF1）以及93737头来自肉牛×肉牛母牛的吮乳饲养动物（BXB）的屠宰记录，实现了这一目标。线性混合模型用于量化不同后代基因型胴体特征的最小二乘均值。模型中调整的干扰固定效应包括：动物杂种优势和重组损失、母畜胎次、屠宰年龄以及同期组；当因变量为屠宰年龄时，屠宰年龄被胴体重和胴体脂肪评分作为自变量所取代。在后续分析中，对模型进行重新分析，其中对父系的遗传价值进行了调整；进一步的分析将母系的遗传价值设置为对于奶牛和肉牛母畜在因变量上相同。最终分析调整为共同的父系和母系遗传价值，便于估计早期饲养策略的差异。无论父系和母系的遗传价值如何，来自肉牛群的动物胴体更重且更符合标准。与DXD动物相比，BXB动物的胴体重67千克，体型评分（从1[差]到15[优]）高5个单位。当所有母畜的遗传价值设定相等时，BXB动物比BXD动物更重且体型更好。当父系和母系的遗传价值都设定相等时，与DXD动物相比，BXB动物的胴体重15千克，体型评分高0.69个单位；这种差异归因于早期生活经历。总之，与肉牛群相比，奶牛群犊牛胴体指标的大部分劣势是由于亲本遗传价值的差异。然而，即使将亲本调整到相同的遗传价值，奶牛群的后代仍然不如出生在肉牛群的同期动物，这很可能是由于早期生活经历的持续性。
