In marine fish larval rearing, the early stages are crucial for determining juvenile health, quality, robustness, and performance during on growing. This initial period is influenced by a complex interplay of factors, including egg quality, environmental conditions, and feeding and nutrition.
A holistic farming approach that integrates all these elements is essential for hatchery success. This involves providing well-balanced nutrients, optimizing feeding strategies, and maintaining optimal rearing conditions.
As every hatchery feeding partner, BioMar has focused efforts on both live feed and dry feed feeding strategies to help hatcheries achieve better results and reduce production costs.
For Starters, Focus on live feeds
Rotifers and Artemia have been the predominant live feeds in the aquaculture industry since the 1970s. Both rotifers and Artemia inherently lack sufficient levels of Omega-3 highly unsaturated fatty acids (HUFAs), specifically DHA and EPA. Thus, there is a need for enrichment to enhance their nutritional profile and meet the requirements of the newly hatched larvae.
But enrichment alone is not enough. DHA and EPA are incorporated into the phospholipid fraction of the lipids, as this form can be used much more efficiently for larval growth and development compared to neutral lipids (triacylglycerols). While it is possible to elevate DHA levels in total lipids through enrichment with many of the available commercial products, the phospholipid content often remains inadequate for the nutritional needs of developing larvae.
LARVIVA Multigain, BioMar´s complete live feed enrichment formula, has been designed and optimized over the years to enrich rotifers and Artemia with all the essential nutrients required by marine fish larvae with a special focus on phospholipids, and it features Bactocell®, a probiotic promoting a healthy gut microbiome.
BioMar conducted a series of trials to develop live feed enrichment protocols that optimize the levels of Omega-3-HUFAs in both total lipids and phospholipids. The trials indicated that the duration of enrichment and the dose of LARVIVA Multigain used were critical for optimal fatty acid incorporation. A long (18-20h) Multigain enrichment is recommended to allow sufficient time for DHA to incorporate into phospholipids. Additionally, BioMar developed a computer model that allows hatcheries to adjust parameters to predict enrichment outcomes or set desired phospholipid DHA levels.
Moving onto Microdiets
As the perfect complement for optimally enriched live prey, the transition to a high quality microdiet will have a profound effect on the outcome. But as it happens with the enrichment, for the best potential results in any hatchery, using the best microdiet in the market will not be enough. Feed and feeding need to be adapted to the technical characteristics of the facility, as well as to the physical behavior of the feed that is being used.
LARVIVA ProStart is BioMar´s premium larval feed, with a manufacturing process that ensures nutrient preservation and maximizes physical quality. It is designed to support early larval development up to the post weaning phase, it is nutritionally formulated and balanced to comprehensively fulfil all nutritional requirements of marine fish larvae and, as LARVIVA Multigain, it includes the probiotic Bactocell with a proven positive effect on nutrient assimilation in fish.
For the best potential results, as was done for the enrichment, BioMar conducted a large-scale trial with seabream larvae to optimize LARVIVA ProStart feeding protocols. The trial´s main objective was to test if a feeding strategy relying on the prolonged use of a Top-Quality microdiet like ProStart over the whole larval rearing showed advantages and proved economically sound versus the use of strategies making use of standard, more economical, diets.
The findings from the trial unequivocally indicate that the prolonged use of LARVIVA ProStart until the end of weaning enhances larval performance over the use of standard diets at the late weaning phase. Furthermore, indications from this trial and previous experience point towards the early introduction of microdiet as a beneficial strategy to accelerate digestive system maturation translating into improved performance.
In order to address cost-efficiency, the cost of feeding consumables (artemia cysts, enrichment products, dry feeds) plus the costs of hiring extra staff for removing excess deformities, were combined with the final amount of good quality larvae to obtain a direct-cost analysis.
The results indicate that extending the use of LARVIVA ProStart throughout the entire larval and weaning cycle results in very significant reductions in costs. Despite being more expensive than standard diets, adopting prolonged LARVIVA ProStart strategies remain cheaper overall than strategies which rely on standard, more economical, diets for weaning.
Conclusion
Producing good quality marine larvae is among the greatest challenges that can be found in animal rearing. The complex interplay of factors affecting culture units forces producers to pay enormous attention to detail and to control every aspect of hatchery operation.
Feed and feeding are paramount to achieve this success, starting by the enrichment of rotifers and Artemia with the required fatty acids, particularly in phospholipids, which is crucial for meeting the nutritional needs of fish larvae. LARVIVA Multigain has been designed with this in mind, and the results here presented have served as the base to develop the optimal enrichment protocols for each hatchery to achieve optimal fatty acid levels in their live feed.
Along with the live feed, the introduction, transition and weaning onto dry diets will be instrumental drivers of juvenile quality, the use of LARVIVA ProStart, a top quality microdiet, during larval rearing and weaning has proven to not only enhance culture performance, but to do it while significantly reducing production cost when compared to weaning with feeds at a reduced price. Additionally, the early introduction of LARVIVA ProStart at mouth opening, contributes to further improving results by promoting an early maturation of the digestive system.
In conclusion, the use of LARVIVA Multigain and LARVIVA ProStart, and the adoption of effective live feed and microdiet feeding protocols are powerful tools for boosting hatchery success. By providing well-balanced nutrients, optimizing feeding strategies, and maintaining the best possible hatchery conditions, hatcheries can significantly improve the survival rates and overall health and robustness of fish larvae. A strong start is indeed the key to sustained success in aquaculture.
Get here the article with the full trial and complete results.
