EUROPE - The period of transfer from the hatchery to the sea cage, is a challenging time for marine fish fry. Young fish are more prone to disease and stress after travelling long distances to the sea. However, with the help of new starter and transfer feeds, fish performance and health can be maintained to the highest standard during this difficult period.
"Marine fish fry are produced in hatcheries where the environment parameters like water filtration, temperature, light and bacterial contamination are controlled and stable," explained Michel Autin, Technical Director for BioMar’s EMEA Division and Stéphane Ralite, Aquaculture Product Manager at Lallemand Animal Nutrition, speaking to The Fish Site.
"When fry are transferred from this protected environment to sea cages, they are usually transported by truck or boat at high density for one or two days, and then released into large cages in the open sea. Here, the environment is more aggressive and fish can have to face parasites or pathogens," they continued.
In order to help Mediterranean fish fry species, such as seabass, seabream and meagre, cope with the introduction to an uncontrolled environment and to reduce post-transfer losses, the new feeds from BioMar, named INICIO Plus M and INTRO Plus MT, combine B-Wyse™, a new yeast based functional ingredient, the probiotic Bactocell® and high doses of anti-oxidant vitamins C and E.
"Together with the other ingredients in the feed, the combination of Bactocell and B-Wyse provides higher resistance to disease and better performance, as has been documented in BioMar and Lallemand tests, both in controlled conditions and in large scale trials," explained Mr Autin.
Developed by Lallemand, B-Wyse is a combination of several yeast strains that have been selected with a new technology - Atomic Force Microscopy (ATM) - that allows the yeast to be evaluated for its capacity to attach to pathogens at the molecular level.
“The yeast strains are found in the natural environment, making it a natural and sustainable ingredient. Furthermore, the quantities needed are small compared to other ingredients and so the cost/benefit of their use is positive,” said Mr Ralite.
"It can also be produced with low impact technologies and has no negative environmental consequences in the farm outlet, or in hatchery water quality," Mr Ralite added.
B-Wyse is also very beneficial to the fish for the production of mucus, which is one of the most important defence mechanisms for fighting off pathogens. By strengthening the mucosal barriers in intestines, skin and gills, the external barriers of the fish are boosted against environmental threats.
Field tests revealed that mucus production was increased in salmon and trout fed the B-Wyse feed vs a control feed and seabass showed +18 per cent more mucus when fed Bactocell+B-Wyse.
“The use of Bactocell in the feed offers a natural way to re-inforce fish health through synergetic immune response,” said Mr Autin.
The probiotic, which is the only probiotic approved for the use in aquaculture in the EU, reduces vertebral deformities in the fish. It has also been shown to improve gut health and increase resistance to bacterial diseases.
"Various test show that the combination of B-Wyse and Bactocell have clear positive impacts on health parameters and by this is perfectly suited to strengthen the fragile marine fry and prepare it for transfer to the harsh environment in sea cages,” Mr Autin added.
Furthermore, the new starter and transfer feeds present a higher digestible protein/digestible energy ratio, with the objective to better control and to lower fat deposition around the gut and therefore create better liver condition of the fish, which contributes to enhancing its global health status.
"It is very common to have excess fat in the gut of farmed fish and this has a negative influence on the overall health of the fish. Using a lower fat diet in juveniles’ feed combined with proper feeding practices helps better control this,” said Mr Autin.
"We are confident that our customers soon will experience the positive effects of this revolutionary new concept as we expect that our new marine fry and transfer feeds considerably will improve survival rates and the health status the fragile young fish and protect them against some of the very common diseases in Mediterranean fish farming,” Mr Autin concluded.