FEEDS
Wet multi-layer microdiet for easier weaning of marine fish Abdeslam EL HARRAK, Huddle Corp.
What are the needs of the aquaculture industry at the hatchery level in terms of feed? At the stage where fish are most vulnerable, it is very important that every aspect of their environment is precisely managed to limit the risk of mortality, deformities, and exposure to disease. Different feeds and feeding regimes play a role in mitigating these risks, and although the industry is teeming with different products, a catch-all solution has yet to be found. Therefore, hatcheries must combine the use of several products in order to find what works for their own conditions: finding a solution becomes a real art for hatchery managers more or less based on well-described science. However, despite these differences in hatcheries, there seems to be a standard regime that includes the use of live feed with a period of weaning that leads to a dried inert diet. While it cannot be denied that Artemia and other types of live feed have supported hatchery production up until now, there is a global trend spanning several companies and research institutes to develop practical and scalable solutions to replace Artemia and other live prey with inert feed.
Weaning strategy with inert dry feed Studies highlighted that the replacement of Artemia with dry inert feed was quite challenging. Compound diets are well ingested at the early stage, but larvae are unable to take enough benefit from dry micro-diet. The digestibility and nutritional availability of the dry micro diet were the object of biochemical studies over more than 20 years and have shown that most of the digestive enzymes are present in young larvae and that inadequate diets can delay or maintain the secretion mechanisms for larvae with early weaning inducing mortality and poor growing. Are the dry micro-particles feed too concentrated for the digestive capacity of the larvae? Common
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Seabass larvae at DPH 10 eating VivoHatch®
industrial processes, such as marumerization, spray drying, or micro extrusion, have to manage questions like homogenous composition – especially for smallsize preparation – or low leaching in the water and compromises are difficult to find with additional specifications like palatability, digestibility of particles, and water buoyancy. Dry feeds are in breaking edge with live feeds mainly due to the amount of dry matter consumed by the larvae per particle. The intake of the available nutrient concentration by the larvae is completely different and digestive behavior cannot be similar.
Hatchery Feed & Management Vol 11 Issue 4 2023