Endogenous and nutritional determinants of protein and lipid deposition in fish

点击翻译按钮获取中文摘要

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.