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Genetic parameters and genomic breeding values for digital dermatitis in Holstein Friesian dairy cattle: host susceptibility, infectivity and the basic reproduction ratio.
Genetics Selection Evolution ( IF 4.1 ) Pub Date : 2019-11-20 , DOI: 10.1186/s12711-019-0505-3
Floor Biemans 1, 2 , Mart C M de Jong 1 , Piter Bijma 2
Affiliation  

BACKGROUND For infectious diseases, the probability that an animal gets infected depends on its own susceptibility, and on the number of infectious herd mates and their infectivity. Together with the duration of the infectious period, susceptibility and infectivity determine the basic reproduction ratio of the disease ([Formula: see text]). [Formula: see text] is the average number of secondary cases caused by a typical infectious individual in an otherwise uninfected population. An infectious disease dies out when [Formula: see text] is lower than 1. Thus, breeding strategies that aim at reducing disease prevalence should focus on reducing [Formula: see text], preferably to a value lower than 1. In animal breeding, however, [Formula: see text] has received little attention. Here, we estimate the additive genetic variance in host susceptibility, host infectivity, and [Formula: see text] for the endemic claw disease digital dermatitis (DD) in Holstein Friesian dairy cattle, and estimate genomic breeding values (GEBV) for these traits. We recorded DD disease status of both hind claws of 1513 cows from 12 Dutch dairy farms, every 2 weeks, 11 times. The genotype data consisted of 75,904 single nucleotide polymorphisms (SNPs) for 1401 of the cows. We modelled the probability that a cow got infected between recordings, and compared four generalized linear mixed models. All models included a genetic effect for susceptibility; Models 2 and 4 also included a genetic effect for infectivity, while Models 1 and 2 included a farm*period interaction. We corrected for variation in exposure to infectious herd mates via an offset. RESULTS GEBV for [Formula: see text] from the model that included genetic effects for susceptibility only had an accuracy of ~ 0.39 based on cross-validation between farms, which is very high given the limited amount of data and the complexity of the trait. Models with a genetic effect for infectivity showed a larger bias, but also a slightly higher accuracy of GEBV. Additive genetic standard deviation for [Formula: see text] was large, i.e. ~ 1.17, while the mean [Formula: see text] was 2.36. CONCLUSIONS GEBV for [Formula: see text] showed substantial variation. The mean [Formula: see text] was only about one genetic standard deviation greater than 1. These results suggest that lowering DD prevalence by selective breeding is promising.

中文翻译:

荷斯坦黑白花奶牛数字性皮炎的遗传参数和基因组育种值:寄主易感性,传染性和基本繁殖率。

背景技术对于传染病,动物被感染的可能性取决于其自身的易感性,以及传染性同伴的数量及其传染性。连同传染期的持续时间,易感性和传染性一起决定了该疾病的基本繁殖率([公式:见正文])。[公式:见正文]是在没有感染的人群中,典型的感染者引起的平均继发病例数。当[公式:参见文本]低于1时,传染病就会消失。因此,旨在降低疾病患病率的育种策略应集中于降低[公式:参见文本],最好降低到小于1的值。在动物育种中,但是,[公式:参见文字]很少受到关注。在这里,我们估算宿主易感性的累加遗传方差,宿主感染性,以及荷斯坦黑白花奶牛的地方性爪状疾病数字皮炎(DD),并估算这些特征的基因组育种值(GEBV)。我们记录了来自荷兰12个奶牛场的1513头母牛的后爪的DD病状态,每2周11次。基因型数据由1401头母牛的75,904个单核苷酸多态性(SNP)组成。我们对两次录音之间母牛被感染的可能性进行了建模,并比较了四个广义线性混合模型。所有模型都包括易感性的遗传效应。模型2和4还包括传染性的遗传效应,而模型1和2包括农场*时期的相互作用。我们通过抵消补偿了对传染性羊群接触的变化。结果[公式:从包含遗传敏感性遗传模型的模型中,基于农场之间的交叉验证,其准确度仅为〜0.39,考虑到数据量有限和性状复杂性,该准确性非常高。具有传染性遗传效应的模型显示出较大的偏差,但GEBV的准确性也略高。[公式:参见文本]的相加遗传标准偏差较大,即〜1.17,而平均值[公式:参见文本]为2.36。结论[公式:见正文]的GEBV表现出很大的差异。平均值[公式:参见文字]仅约为1的遗传标准偏差。这些结果表明通过选择性育种降低DD患病率是有希望的。考虑到有限的数据量和特征的复杂性,这是非常高的。具有传染性遗传效应的模型显示出较大的偏差,但GEBV的准确性也略高。[公式:参见文本]的相加遗传标准偏差较大,即〜1.17,而平均值[公式:参见文本]为2.36。结论[公式:见正文]的GEBV表现出很大的差异。平均值[公式:参见文字]仅约为1的遗传标准偏差。这些结果表明通过选择性育种降低DD患病率是有希望的。考虑到有限的数据量和性状的复杂性,这是非常高的。具有传染性遗传效应的模型显示出较大的偏差,但GEBV的准确性也略高。[公式:参见文本]的相加遗传标准偏差较大,即〜1.17,而平均值[公式:参见文本]为2.36。结论[公式:见正文]的GEBV表现出很大的差异。平均值[公式:参见文字]仅约为1的遗传标准偏差。这些结果表明通过选择性育种降低DD患病率是有希望的。结论[公式:见正文]的GEBV表现出很大的差异。平均值[公式:参见文字]仅约为1的遗传标准偏差。这些结果表明通过选择性育种降低DD患病率是有希望的。结论[公式:见正文]的GEBV显示出很大的差异。平均值[公式:参见文字]仅约为1的遗传标准偏差。这些结果表明通过选择性育种降低DD患病率是有希望的。
更新日期:2020-04-22
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