GenPhySE, INRAE, ENVT, Université de Toulouse, 31326, Castanet-Tolosan, France.
PECTOUL, INRAE, 31326, Castanet-Tolosan, France.
Genet Sel Evol. 2020 Jun 26;52(1):34. doi: 10.1186/s12711-020-00552-8.
Pasteurellosis (Pasteurella infection) is one of the most common bacterial infections in rabbits on commercial farms and in laboratory facilities. Curative treatments using antibiotics are only partly efficient, with frequent relapses. Breeding rabbits for improved genetic resistance to pasteurellosis is a sustainable alternative approach. In this study, we infected 964 crossbred rabbits from six sire lines experimentally with Pasteurella multocida. After post-mortem examination and bacteriological analyses, abscess, bacteria, and resistance scores were derived for each rabbit based on the extent of lesions and bacterial dissemination in the body. This is the first study to use such an experimental design and response traits to measure resistance to pasteurellosis in a rabbit population. We investigated the genetic variation of these traits in order to identify potential selection criteria. We also estimated genetic correlations of resistance to pasteurellosis in the experimental population with traits that are under selection in the breeding populations (number of kits born alive and weaning weight).
Heritability estimates for the novel response traits, abscess, bacteria, and resistance scores, ranged from 0.08 (± 0.05) to 0.16 (± 0.06). The resistance score showed very strong negative genetic correlation estimates with abscess (- 0.99 ± 0.05) and bacteria scores (- 0.98 ± 0.07). A very high positive genetic correlation of 0.99 ± 0.16 was estimated between abscess and bacteria scores. Estimates of genetic correlations of the resistance score with average daily gain traits for the first and second week after inoculation were 0.98 (± 0.06) and 0.70 (± 0.14), respectively. Estimates of genetic correlations of the disease-related traits with average daily gain pre-inoculation were favorable but with high standard errors. Estimates of genetic and phenotypic correlations of the disease-related traits with commercial selection traits were not significantly different from zero.
Disease response traits are heritable and are highly correlated with each other, but do not show any significant genetic correlations with commercial selection traits. Thus, the prevalence of pasteurellosis could be decreased by selecting more resistant rabbits on any one of the disease response traits with a limited impact on the selection traits, which would allow implementation of a breeding program to improve resistance to pasteurellosis in rabbits.
巴氏杆菌病（巴氏杆菌感染）是商业农场和实验室设施中兔子最常见的细菌性感染之一。使用抗生素的治疗效果只有部分有效，且经常复发。培育对巴氏杆菌病具有遗传抗性的兔子是一种可持续的替代方法。在这项研究中，我们用多杀性巴氏杆菌对来自六个父系的 964 只杂交兔进行了实验性感染。在死后检查和细菌学分析后，根据兔体病变和细菌传播程度，为每只兔确定了脓肿、细菌和抗性评分。这是首次使用这种实验设计和响应特征来衡量兔群对巴氏杆菌病的抗性。我们研究了这些特征的遗传变异，以确定潜在的选择标准。我们还估计了实验种群中对巴氏杆菌病的抗性与在繁殖种群中选择的特征（活产仔数和断奶体重）之间的遗传相关性。
新的反应特征脓肿、细菌和抗性评分的遗传力估计值在 0.08（±0.05）至 0.16（±0.06）之间。抗性评分与脓肿（-0.99±0.05）和细菌评分（-0.98±0.07）之间存在非常强的负遗传相关性估计。脓肿和细菌评分之间的遗传相关性非常高，为 0.99±0.16。在接种后第一和第二周的平均日增重性状中，抗性评分的遗传相关性估计值分别为 0.98（±0.06）和 0.70（±0.14）。疾病相关性状与接种前平均日增重的遗传相关性估计值是有利的，但标准差较高。疾病相关性状与商业选择性状的遗传和表型相关性估计值与零无显著差异。
疾病反应性状是可遗传的，彼此高度相关，但与商业选择性状没有显著的遗传相关性。因此，可以通过选择对巴氏杆菌病具有更强抗性的兔子，在任何一种疾病反应性状上，都可以在有限程度上影响选择性状，从而降低巴氏杆菌病的流行率，同时允许实施一个改良兔子对巴氏杆菌病抗性的育种计划。
