New mastitis phenotypes suitable for genomic selection in meat sheep and their genetic relationships with udder conformation and lamb live weights
New mastitis phenotypes suitable for genomic selection in meat sheep and their genetic relationships with udder conformation and lamb live weights
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适合肉羊基因组选择的新乳腺炎表型及其与乳房构象和羔羊活重的遗传关系
DOI：
10.1017/s1751731118000393
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发表时间：
2018
期刊：
影响因子：
3.6
通讯作者：
McLaren A
中科院分区：
文献类型：
--
作者：
McLaren A
事实证明，由于处理方法、羔羊生长不良和过早扑杀母羊的成本，饲养用于肉类生产的绵羊患乳房炎的成本可能很高。在乳制品系统中，检测乳房炎最常用的方法是体细胞计数。然而，在许多产肉绵羊群中，母羊不是常规处理的，因此不可能总是进行定期的牛奶采样。因此，值得研究其他表型，如与乳房构象有关的表型，以及评估牛奶中体细胞数量的方法，如加州乳房炎试验。因此，本研究的主要目的是：(A)估计肉用绵羊品种中与乳房炎和乳房形态有关的性状的遗传参数；(B)估计体细胞计数与加利福尼亚乳房炎试验之间的关联程度；以及(C)评估乳房炎与乳房形态和羔羊活重之间的关系。数据是在2015年至2016年期间从英国各地29只特克塞尔母羊身上收集的。每年对母羊进行两次评分，时间为哺乳中期和后期。记录了8种不同的构象特征，与乳房和乳头特征有关，以及乳样。该数据集包括2957只母羊的可用数据。使用的谱系档案包含31775个个体的父系和母系信息。所使用的动物模型符合相关的固定和随机效应。与乳房炎有关的性状(体细胞评分和加利福尼亚乳房炎试验)的遗传力估计分别在0.08到0.11和0.07到0.11之间。体细胞评分与加利福尼亚乳房炎试验之间有很高的遗传相关性(0.76~0.98)，表明加利福尼亚乳房炎试验值得用来评估感染水平，特别是在哺乳期中期。乳房炎性状与乳房形态性状的相关性最强的是乳房深度(0.61~0.75)，也是在哺乳中期。乳房炎与母羊饲养的羔羊体重呈负相关(−为0.15~−为0.23)，表明羔羊体重随感染水平的升高而下降。遗传相关性与零没有显著差异。减少乳房炎将导致畜群生产力的提高以及动物的健康和福利。它还将提高生产效率和应对疾病挑战的能力。因此，这些结果的综合经济效益不仅在这个品种上，而且在整个肉羊业中都是可观的。
Mastitis can prove expensive in sheep reared for meat production due to costs associated with treatment methods, poor lamb growth and premature culling of ewes. The most commonly used method to detect mastitis, in dairy systems, is somatic cell counts. However, in many meat-producing sheep flocks ewes are not routinely handled, thus regular milk sampling is not always possible. It is, therefore, worthwhile to investigate alternative phenotypes, such as those associated with udder conformation and methods of evaluating somatic cell counts in the milk, such as the California Mastitis Test. The main objectives of this study were therefore: (a) to estimate genetic parameters of traits relating to mastitis and udder conformation in a meat sheep breed; (b) estimate the level of association between somatic cell counts and the California Mastitis Test and (c) assess the relationships between mastitis and both udder conformation and lamb live weights. Data were collected from Texel ewes based on 29 flocks, throughout the UK, during 2015 and 2016. The ewes were scored twice each year, at mid- and late-lactation. Eight different conformation traits, relating to udder and teat characteristics, and milk samples were recorded. The data set comprised of data available for 2957 ewes. The pedigree file used contained sire and dam information for 31 775 individuals. The animal models used fitted relevant fixed and random effects. Heritability estimates for traits relating to mastitis (somatic cell score and the California Mastitis Test), ranged from 0.08 to 0.11 and 0.07 to 0.11, respectively. High genetic correlations were observed between somatic cell score and the California Mastitis Test (0.76 to 0.98), indicating the California Mastitis Test to be worthwhile for assessing infection levels, particularly at mid-lactation. The strongest correlations observed between the mastitis traits and the udder conformation traits were associated with udder depth (0.61 to 0.75) also at mid-lactation. Negative phenotypic correlations were estimated between mastitis and the weight of lamb reared by the ewe (−0.15 to −0.23), suggesting that lamb weights fell as infection levels rose. Genetic correlations were not significantly different from zero. Reducing mastitis will lead to improvements in flock productivity and the health and welfare of the animals. It will also improve the efficiency of production and the resilience to disease challenge. The economic benefits, therefore, of these results combined could be substantial not only in this breed but also in the overall meat sheep industry.