Endogenous and nutritional determinants of protein and lipid deposition in fish

鱼类营养的“最新技术”是在可消化蛋白质（DP）和可消化能量（DE）的基础上制定饲料，并使用生物能量学模型来估计产量和饲料口粮。这些方法很有用，而且用户友好。然而，它们有严重的局限性，因为它们过于简单。因此，我的研究计划的中心目标是开发更合理和机械的方法来表示鱼类的生长、饲料和营养利用。为了实现这一目标，我正在开展研究，以获取关于营养利用方面文献记录不足的信息，并通过构建模型整合现有信息。我使用的方法认识到动物的生长是由身体成分（水、蛋白质、脂质、矿物质等）的增加决定的。沉积体成分的数量和营养物质转化为体成分的效率是决定鱼类饲料需要量和废物产量的主要因素。沉积体成分的数量和营养物质转化的效率受到许多内源（物种、遗传、生命阶段）和外源（日粮组成、饲养水平、环境、季节）因素的影响。为了建立准确的模型，必须检查这些不同因素的影响。拟建项目将1)表征磷脂和甘油三酯沉积和动员过程作为膳食和内源性因素的功能，2)更好地定义脂质摄入、甘油三酯沉积速率和脂质储存对氨基酸分解代谢的影响，以及大型（>500 g）虹鳟鱼多余氨基酸转化为脂肪酸的效率，以及3-)建立一个考虑鱼类生物学的机械营养流动模型。鱼类日粮营养利用和分配的特点及水产养殖生产的制约因素。

The "state-of-the-art" in fish nutrition is the formulation of diet on a digestible protein (DP) and digestible energy (DE) basis, and the use of bioenergetics models to estimate production and feed rations. These approaches are useful and user-friendly. However, they have serious limitations since they are too simplistic. The central objective of my research program is, therefore, to develop more rational and mechanistic approaches of representing growth, and feed and nutrient utilization in fish. I am attempting to achieve this objective by carrying out studies to generate information on poorly documented aspect of nutrient utilization, and by integrating available information through the construction of models. The approach I use recognizes that growth of animals is determined by the accretion of body components (water, proteins, lipids, minerals, etc.).  The amounts of body component deposited and efficiency with which nutrients are converted into body components are the main factors determining feed requirement and waste outputs of fish. The amount of body components deposited and the efficiency with which the nutrients are converted, are affected by numerous endogenous (species, genetics, life stage) and exogenous (diet composition, feeding level, environment, season) factors. It is essential to examine the effects of these different factors in order to develop accurate models. The proposed project will 1) characterize phospholipids and triglycerides deposition and mobilization processes as a function of dietary and endogenous factors, 2) better define the effect of lipid intake, triglyceride deposition rate, and lipid stores on amino acid catabolism, and the efficiency conversion of surplus amino acids into fatty acid in large (>500 g) rainbow trout, and 3-) develop a mechanistic nutrient-flow model that takes into account the biology of fish, the characteristics of dietary nutrient utilization and partitioning in fish, and the constraints associated with aquaculture production.