Breeding for resistance or tolerance to coccidia in broiler chickens

肉鸡是最密集选择用于生产的家养物种，艾美耳球虫（球虫）感染是对其健康和生产力最普遍的挑战，估计每年给英国工业造成超过8000万英镑的损失。其控制的各种方法要么是无效的，要么受到长期可持续性的威胁，例如球虫对药物的抗性的发展。通过遗传选择来控制导致这种大量生产损失的疾病的问题仍然没有解决，尽管这是一种有吸引力的可能性。育种者可以选择利用两种宿主策略：抗性（限制病原体复制的能力）和耐受性（限制对宿主生产力或健康影响的能力）。这两种策略对感染结果的相对贡献知之甚少。统计方法分析个体水平上耐受性的遗传基础，并将其视为静态而非动态性状，这阻碍了人们对耐受性的理解。我们最近开发了一种克服这些局限性的方法，通过考虑同时描绘感染严重程度和性能变化的个体感染动态轨迹。本项目的目的是将该方法应用于肉鸡艾美耳球虫感染，以确定：1）对艾美耳球虫的耐受性是否存在遗传变异; 2）不同生产强度下选择的肉鸡基因型如何映射到不同的轨迹类型; 3）这些基因型在对感染的抵抗力和耐受性方面是否相似，以及4）该排名是否受到不同免疫反应调节的不同球虫感染的影响。该提案完全福尔斯BBSRC战略研究优先事项1：农业和粮食安全的职权范围。这与BBSRC的目标是一致的，即“支持对食品安全和食品安全具有深远影响的领域的研究，例如动物健康和福利，以及用于提高产量和抗病能力的遗传学和基因组学”。其目的是支持基础和战略研究，以制定防治地方病的干预战略，在英国（以及在适当的情况下，在国际范围内）为食品生产而养殖的动物或对英国经济具有重要意义的其他驯养动物的福利。学生将接受与食品安全和食品安全（动物育种和遗传学，寄生虫学，动物科学，统计技术）相关的多个学科的培训，通过这样做，它将推进BBSRC的目标，即“确保英国技能基础具有适当的临界质量和专业研究专长，以支持这些学科”。

Broiler chickens are the domestic species most intensively selected for production and Eimeria (coccidia) infections are the most pervasive challenge to their health and productivity, estimated to cost the UK industry > £80m per annum. The various method of its control are either not effective or are threatened by long term sustainability, such as the development of coccidian resistance to drugs The issue of controlling through genetic selection for diseases that cause such substantial production losses remains unresolved, although it is an attractive possibility. The breeder has the choice of exploiting two host strategies: resistance to (the ability to limit pathogen replication) and tolerance of (the ability to limit the impact on host productivity or health). The relative contribution of these two strategies to infection outcomes, is poorly understood. Understanding has been hampered by statistical methods to analyse the genetic basis of tolerance at individual level and by considering it as a static as opposed to a dynamic trait. We recently developed a methodology that overcomes these limitations, by considering individual infection dynamic trajectories portraying simultaneously changes in infection severity and performance. The aim of this project is to apply this methodology to Eimeria infections of broilers to determine: 1) whether there is genetic variation in tolerance to Eimeria; 2) how broiler chicken genotypes selected for different production intensities map onto distinct trajectory types; 3) whether these genotypes rank similarly in terms of resistance and tolerance to infection and 4) whether this ranking is affected by different coccidian infections regulated by different immune responses.The proposal falls entirely under the remit of BBSRC Strategic Research Priority 1: Agriculture and Food Security. It is consistent with BBSRC aim to 'support research in areas that have profound implications for food security and food safety, such as animal health and welfare, and genetics and genomics for improved production and disease resistance'.The studentship falls within the remit of the animal Health priority of BBSRC, which aims to to support fundamental and strategic research leading to the development of intervention strategies for combating endemic diseases that reduce the health and welfare of either animals farmed for food production in the UK (and where appropriate, in the international context) or other domesticated animals of importance to the UK economy. The student will be trained in a number of disciplines that are of relevance to food security and food safety (animal breeding and genetics, parasitology, animal science, statistical techniques), and by doing so it will advance the BBSRC aim of 'ensuring that the UK skills base has appropriate critical mass and specialist research expertise to support these disciplines'.