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Dr Neil Auchterlonie Exploring ISAAH
ast week I was lucky enough to attend the International Symposium on Aquatic Animal Health (ISAAH), held in Charlottetown, Prince Edward Island Canada. This event, held on a four-year cycle, draws aquatic animal health professionals from across the world.
The Symposium ran over the whole week, with many different sessions, and there was a great diversity of fish species discussed, reflecting the growth in aquaculture over time. As well as the usual suspects of the modern aquaculture industry, there were even special sessions devoted to the health of cleaner fish, ornamental fish, and zebra fish (for laboratory studies), so it really was all-encompassing in terms of the coverage of subject matter. I was not attending the Symposium out of personal interest though, nor was I on holiday, even though Charlottetown appeared to be a very picturesque location, and worthy of some time spent as a tourist. IFFO had submitted an abstract in order to provide a technical presentation within one of the sessions, the QASH project session. QASH is an acronym that stands for Quantitative Atlantic Salmon Health Assessment, and the project is a collaboration between scientists in Norway, Scotland, Chile and Canada, led by Prof Karin Pittman of the University of Bergen. The aim of QASH is to develop tools that permit rapid and accurate measurements of farmed salmon health, indicating very strong real-world applications of the research. Within salmon farming there are some clear health challenges, often linked directly to pathogens such as sea lice, piscirickettsia, gill amoebae, salmonid alphavirus. The session was split into three, focusing on biomarkers, barriers and stressors, and available toolboxes, with some lively discussion at the end. My IFFO paper focused on the link between nutrition and health in farmed salmon, exploring the changing profile of salmon feeds over time and the nutritional variability that has resulted. None of this is earth-shattering in terms of the messages and many are aware of the substantial progress that has been made in the substitution of marine ingredients over time. That research has largely been undertaken by the feed companies, responding to market competition over time with their changing formulations. Much of this research is understandably commercial and confidential. Although some of the information has reached the public domain, the majority has not. Fish performance, as measured by growth and feed conversion rate, over the time of these changing diets, has been maintained in comparison to the majority marine ingredient diets of 25 years ago. What these metrics fail to consider, is the health and robustness of farmed fish, and although growth is often regarded as a decent proxy for health and welfare it does not tell the whole picture. Equally important to understand is the ability of the fish to cope with infection and physical stressors relevant to modern farming practices. This is less a story about the provision of crude protein and energy in salmon feed and more a story of the micronutrients, and fishmeal is a tremendous source of many of those micronutrients. In terms of nutritional needs for the species, we need look no further than what Atlantic salmon eat in the wild, and in the process of developing my presentation I uncovered a paper that notes the prey items of wild post-smolts in the North Atlantic – blue whiting, sand eels and herring – all important raw materials for fishmeal! Dr Neil Auchterlonie is the Technical Director at IFFO. He has managed aquaculture and fisheries science programmes in both public and private sectors. Academically he holds a BSc in Marine and Freshwater Biology from Stirling University, a MSc in Applied Fish Biology from the University of Plymouth, and a PhD in Aquaculture (halibut physiology) from Stirling University. 10 | October 2018 - International Aquafeed
Targeting fish immunity and natural defences through nutrition
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ew results were revealed in presentations at the AQUA 2018 conference, by Lallemand Animal Nutrition, involving our understanding of aquafeed ingredients and their betterment towards supporting fish health, performance and welfare. Functional feeds are growing to become a crucial component of modern aquafeed to support a responsible and high-performing aquaculture industry. Lallemand’s study discussed fish mucosal surfaces, which constitute an effective line of defences but are also constantly exposed to a high quantity of potential pathogens and non-infectious disrupting factors, such as a physical transfer or chemical exposure during production. Lallemand Animal Nutrition allows for selective application of certain functional ingredients to support and maintain the physical, immunological, and microbial components of the fish mucosal barriers. A study, developed in partnership with the University of Plymouth, followed the expression of 62 targeted genes implicated in mucosal responses, cell mediated immunity, stress and hormonal immunity. This genomic technology was designed to better understand immunomodulatory effects and downstream signalling cascades activated at the mucosal levels with selected functional feed ingredients, such as probiotics. Studies also were conducted in other fish species with a multi-strain yeast faction described for its positive effects on bacteria binding, immune modulation and fish skin mucous secretion. A trial carried out in rainbow trout at the University of Plymouth revealed the supplement had a positive effect on musical barrier protection at the gut and skin level. Skin mucus level was around 30 percent higher with the yeast derivative applied. This study indicated the potential of this ingredient at mitigating pathogens during challenging rearing or transfer periods.