膨化温度对鱼类饲料利用及养殖废物营养素归趋过程的影响

Improving feed utilization is an efficient way to reduce feed costs and environmental pollutions for achieving healthy aquaculture. Thermal processing, a key technology of improving feed utilization, is involved in several segments of the commercial feed production line. However, it is still unclear about effects of extrusion temperature on fish feed utilization in aquaculture. Most remarkably, little is known about dynamics of degradation and utilization of aquaculture wastes from fish supplied with feeds at different extrusion temperatures. In this project, we will target herbivorous grass carp (Ctenopharyngodon idellus), a commonly farmed species with the highest productions. The objectives of this project are 1) to explore effects of fishmeal and plant proteins -based feeds at different extrusion temperatures on fish growth performance, fecal compositions and properties, and water quality parameters; 2) to study benthic nutrient cycling at sediment-water interface; 3) and to characterize bacterial community dynamics in sediments from aquaculture wastes and the abundances of functional genes involved in microbial transformations of carbon, nitrogen and phosphorus, as well as the related extracellular enzymatic activity. The results from this project will help in understanding the processes and mechanisms of degradation and utilization of aquaculture wastes, providing insights into theoretical basis for feed productions in term of extrusion technology and environmental protection in aquaculture.

提高饲料利用效率是降低饲料成本、减少环境污染、实现水产养殖绿色发展的关键科学问题之一。热加工是提高饲料利用效率的加工技术之一，普遍应用于水产饲料或原料的加工生产。但饲料的不同膨化温度如何影响其利用效率仍不清楚，而且不同膨化温度的饲料所产生的养殖废物在水环境中如何分解利用缺乏动态的系统的研究。本项目拟以养殖产量最高的草鱼为研究对象，通过开展不同膨化温度加工的鱼粉饲料和植物蛋白饲料的养殖实验，分析鱼类生长、水质变化以及养殖废物的营养物碳氮磷的动态归趋；原位研究养殖产生的沉积物与上覆水营养物的动态过程及特征；分析养殖废物到沉积物转化过程中微生物群落演替及与碳氮磷相关的功能基因的差异和酶活性的改变，揭示养殖废物分解与利用的过程和潜在机制。研究结果将为改进膨化工艺、提高饲料利用效率、减少养殖废物排放提供数据支撑，具有重要理论意义和实际应用价值。

水产养殖的快速发展引起了与养殖业密切相关的饲料增长需求和环境可持续发展的问题。提高饲料利用，减少废物排放是实现水产养殖绿色发展的关键。本项目针对养殖行业中植物蛋白源逐渐替代鱼粉以及膨化饲料产量持续增长的现状，选用草鱼和鲈鱼为研究对象，以不同类型的饲料蛋白（植物蛋白和动物蛋白）为主要蛋白来源，开展饲料加工过程中膨化温度对鱼类生长、饲料利用、肠道及环境微生物、养殖水体碳氮磷动态变化及其环境废物排放等方面的研究。本项目主要发现了饲料膨化温度对鱼类生长性能与饲料利用的影响与饲料主要蛋白源类型相关，更高的膨化温度（140℃）提升了草鱼对植物蛋白源为主饲料的利用，而对动物蛋白为主饲料的利用没有影响；膨化温度改变了摄食植物蛋白为主饲料的草鱼的碳氮沉积有效性和碳氮的环境排放，影响了养殖水体碳氮磷的动态变化和环境微生物的多样性及群落结构；植物蛋白为主的饲料引起更多的碳氮排放，而动物蛋白为主的饲料导致更多的磷排放；此外，鲈鱼养殖的碳氮磷排放低于草鱼。研究结果表明合理选择膨化温度、蛋白类型及养殖品种，可实现提高生长性能，降低水产养殖环境负荷，达到增产减排的目标。本项目的实施为水产养殖高效生产，减少养殖废物排放提供了数据支撑，具有实际应用价值，对水产养殖的可持续发展具有指导作用。