14TSB_ATC_IR: Optimsation and implementation of sterile triploid salmon in Scotland

繁殖不育的三倍体鲑鱼的生产对该行业来说是一种非常有益的养殖选择，有助于防止养殖逃逸鲑鱼与野生鲑鱼之间的潜在杂交，从而实现更可持续的水产养殖，同时提高生产力并保持高营养质量和健康状况的食品。然而，尽管三倍体鲑鱼可以很容易地生产，并且方法已经优化，但在过去，养殖过程中的问题阻碍了该技术在农业部门的采用。在三倍体饲养中遇到的主要问题是骨骼畸形的发生。这些畸形不仅对养殖动物的福利产生重大影响，而且还会降低动物的生长，降低产品加工效率，增加生产成本，并妨碍维持食品质量标准的能力。与哺乳动物不同，鱼类的生长持续一生，是骨骼和肌肉生长之间复杂的相互作用，这是季节性和营养驱动的，因此肌肉和骨骼发育速度的不匹配可能导致骨骼畸形。由于鳍鱼养殖的中心目标是生产肉类，因此了解鱼类营养和环境对肌肉发育和生长的相互作用非常重要。从研究小组过去8年的研究结果来看，二倍体和三倍体发育所需的营养明显不同，这是由于它们在生理、细胞形态和基因组组织方面的根本差异。在这方面，三倍体的主要特征是基因组大小增加（母体染色体增加），其结果不仅使后代不育，而且细胞大小增加，同时细胞数量减少，可能导致基因组不稳定。目前尚不清楚大西洋鲑鱼身上发生了什么，而这些信息对于设计基因改良项目至关重要。本研究的第一个目标是利用基因序列的自然变异来研究哪些染色体拷贝在不同的组织和发育阶段被遗传和表达。然后，我们将研究三倍体如何影响调节肌肉和骨骼生长的激素和基因的信号通路。我们将进行大规模的生命周期试验，其中已知对骨骼发育至关重要的营养物质和矿物质将得到促进，并比较三倍体和二倍体的性能。初步证据已经表明，在淡水养殖早期阶段，磷和其他矿物质在减少畸形发生率和严重程度方面发挥了关键作用。海水养殖期间的研究也将集中在营养增强的饮食上，以实现三倍体鲑鱼的全部生长潜力。最后，该项目将通过挑战研究确定三倍体鲑鱼对主要已知病原体的易感性特征，并测试疫苗副作用以及一系列常规使用的卫生和饲养方法。为了确保项目的成功，该财团汇集了世界领先的鲑鱼养殖公司，包括Marine Harvest Scotland Ltd.、Biomar Ltd.和Pharmaq Ltd.。这项研究将有助于开发常规生产高质量三倍体的实用方法，有利于动物福利和该行业的可持续性和盈利能力。由于养殖鲑鱼是英国饮食中的主要食物来源，每天食用的鲑鱼超过120万份，因此该项目也可以为英国人口的健康和福祉做出重大贡献。通过提高英国养鱼业的可持续性，该项目将有助于保护大部分农村地区6000多个直接就业和与行业相关的工作岗位，并创造新的就业机会。

The production of triploid salmon, which are reproductively sterile, is a highly beneficial culture option to the industry to help prevent potential interbreeding between farmed escapees and wild salmon, thus allowing more sustainable aquaculture whilst enhancing productivity and maintaining a food product of high nutritional quality and health status. However, although triploid salmon can be easily produced and methods have been optimised, problems during culture have prevented the adoption of this technology within the farming sector in the past. The major problem experienced in triploid rearing is the occurrence of skeletal malformations. Not only do such deformities present significant implications for farmed animal welfare, but they can also reduce animal growth, decrease product processing efficiency, increase production costs and prevent ability to maintain food product quality standards. Unlike mammals, growth in fish continues throughout life and is a complex interplay between skeletal and muscle growth which is both seasonally and nutritionally driven, and therefore a mismatch of muscle and bone developmental rates can result in skeletal deformities. Since the central goal of finfish aquaculture is the production of meat, it is therefore important to understand the interactions of fish nutrition and environment on muscle development and growth. From results obtained by the group over the last 8 years, it appears very clearly that the nutritional requirements for development differ between diploids and triploids due to fundamental differences in their physiology, cellular morphology and genome organisation. In this respect, the major feature of triploids is the increased genome size (additional maternal chromosomes), the result of which not only confers sterility in the offspring but also an increase in cell size and a simultaneous reduction in cell number, potentially resulting in genome instability. It is not known what happens in Atlantic salmon and such information is vital for designing genetic improvement programs. The first goal of this research is to use natural variations in the sequence of genes to investigate which chromosomal copies are inherited and expressed in different tissues and stage of development. We will then investigate how triploidy affects the signalling pathways for hormones and genes regulating growth in muscle and bone development. We will carry out a large scale life-cycle trial in which nutrients and minerals known to be critical for the development of the skeleton will be boosted and the performance of triploids and diploids compared. Preliminary evidence already indicated the key role played by phosphorous and other minerals during the early freshwater rearing phase on reducing prevalence and severity of deformity. Research during seawater ongrowing will also focus on nutrient boosted diets to realise the full growth potential of triploid salmon. Finally, the project will characterise triploid salmon susceptibility to major known pathogens through challenge studies and test vaccine side effects as well as a range of routinely used health and husbandry practices. To ensure the success of the project, the consortium brings together world leading companies in salmon farming including Marine Harvest Scotland Ltd., Biomar Ltd. and Pharmaq Ltd. The research will enable the development of practical methods for the routine production of high quality triploids with benefits for animal welfare and the sustainability and profitability of the industry. Since farmed salmon are a major food source in the UK diet, with more than 1.2 million salmon meals eaten per day, this project can also make a significant contribution to the health and well-being of the human population in the UK. By improving the sustainability of the UK fish farming industry, this project will help to protect more than 6000 directly employed and industry-associated jobs in largely rural areas and create new jobs.