2011/701 Atlantic Salmon gastrointestinal health and productivity

By Kamarul Zarman Zarkasi

This project was fundamentally designed to assess and find solutions for "Summer Gut Syndrome" (SGS) in Tasmanian Atlantic Salmon. The focus of the study was to better understand Atlantic Salmon gastrointestinal (GI) microbiology and to connect this data to growth performance, diet formulations and in-farm processes for rapidly assessing salmon with low appetite. Specifically, the project aimed to:

1. Identify key gastrointestinal tract microbial species and community structure drivers that influence most greatly salmonid health.

2. Develop improved knowledge of fish gastrointestinal health in relation to environmental conditions.

3. Develop an in-vitro method to determine effects of different dietary components.

The first outcome of the project was the investigation and publication of improved knowledge of Atlantic Salmon gastrointestinal bacteria within commercial Tasmanian operations. The second study focused on two major goals: 1) How does diet differing in terms of energy and lipid content influence GI tract microbial communities? 2) How does gut flora change in relation to faecal score? The final project explored whether we can develop a rapid in vitro assessment system for GI tract communities of salmon in order to support decisions in feed development.

The results from part one of the project provided a view of the acyclical and highly dynamic community structure in farmed salmon. This data provides a useful baseline for future analysis in terms of defining GI tract communities of fish cohorts and changes that may be related to suboptimal fish performance. The results of part two indicated that diet can influence GI tract communities in farmed salmon but results suggest transient shifts occur despite large diet differences. The development of the rapid in vitro assessment system for GI tract communities demonstrated it has potential for rapid diet formulation pre-testing acting as an avenue to determine survival and growth capacity of probiotic agents and effects of diet additives; however, further improvements to the in vitro testing system are required.