Rainbow trout production worldwide

Rainbow trout (Oncorhynchus mykiss)is one of the most produced freshwater species in the world. Production during 2018 was 850,000 tons globally, with Iran being the first producing country, followed by Turkey and Chile.

At European level, trout production accounts for about 27% of the world’s production, with Italy, Denmark and France being the leading producing countries. Trout production at European level has declined slightly in recent years. However, globally, the production of this specie has increased by a 19% over the past decade, associated with a marked productive increase in Middle East countries.

In recent years Middle Eastern countries such as the UAE, Oman, Egypt and Iran, among others, are boosting the sector with large investments, of both private and public capital, in the aquaculture sector of the region. These countries are betting on aquaculture as safe, cost-effective and ecological animal production, especially in desertic areas. Trout is an ideal specie for these countries due to its ease of cultivation and productive capacity.

Reproductive parameters in trout and related factors

Trout reach sexual maturity at 2-3 years, although in intensive production they can reach sexual maturity at one year age. Trout is a gonocoric species in which females spawn once a year in spring, producing about 2,000 eggs/kg of female.

In intensive production, trout reproduction is done artificially. Both gametes are extracted manually, after sedation of the animals and once extracted, fertilization is carried out artificially. Fertilized eggs are incubated for 21-28 days in vertical or horizontal incubators.

It is important to ensure the availability of good quality larvae for all aquaculture productions. In the case of trout, artificial reproduction mechanisms have been studied for many years and there are standardized protocols.

However, both egg hatchability and larval survival are conditioned by numerous factors. Among these factors is especially relevant the general status of the breeders, both females, as well as sexually reversed males or females. Under optimal conditions the egg hatchability rate varies between 60-90%.

If the condition of the females is adequate, they will be able to transfer a greater amount and quality of nutrients to the eggs, improving the quality of these and accumulating a greater amount of nutrients in the yolk. Therefore, the general status of females has a direct effect on embryonic development and on the viability of larvae during the first weeks of life.

In the case of sexually reversed males or females, the general state has a direct impact on sperm quality.

Pronutrients – natural solution to improve reproductive parameters in trout

Pronutrients are an effective tool to ensure the overall condition of breeders and improve reproductive parameters in trout. Pronutrients are active molecules of botanical origin that act at the metagenetic level optimizing the normal physiological functioning of the animal.

hese pronutrients induce gene expression associated with functional protein synthesis by improving the functions of cells and animal´s organs.

From Biovet S.A. we have developed AVAL Premium, a natural product based on the combination of different pronutrientes together with amino acids and vitamins, which ensure the overall condition of breeders and improve reproductive capacity in trout. This nutritional supplement provides, among other vitamins, vitamin C closely related to the gonadal development and vitamin E which relates to the gonad quality and the egg hatchability .

This nutritional supplement contains intestinal conditioner pronutrients, which improve the integrity of the intestinal epithelium, thanks to a higher rate of renewal of the enterocytes and the improvement of the joints unions between these intestinal cells. It also provides immunostimulant pronutrients, which enhance both specific and non-specific immune response to improve fish resistance to infections, and liver conditioner pronutrients, which allow to ensure the functioning of the liver, essential for the metabolism of lipids and proteins and, therefore, for a good general condition of the animal. At the same time, intestinal conditioner pronutrients improve the absorption and use of vitamins and amino acids provided by the product.

The product has been evaluated in field conditions in a study conducted in rainbow trout in Pakistan at the end of last year (2020) with 4. 500 females. Egg hatchability rate was evaluated following the administration of this pronutrient-based nutritional supplement.

Two experimental groups were performed, a control group with without pronutrients and an experimental group with AVAL Premium at a dose of 5 ml/kg in feed.

The fertility rate in females in the control group was 15-20%, while in the case of females supplemented with pronutrients fertility reached 40%, which means a 100% improvement in egg hatchability rate.

Conclusion

Rainbow trout (Oncorhynchus mykiss) is one of the most produced freshwater aquaculture species in the world and its production will increase markedly in the coming years in Middle East countries.

Although artificial breeding methods in this species are widely known, there are several factors that can affect the viability of eggs and larvae. The overall condition of the breeders is one of the most important factors, since the quality of the gametes and the yolk depends on it.

AVAL Premium is a natural product based on pronutrients, active molecules of botanical origin, capable of improving intestinal health, optimizing the immune response and ensuring liver function. The combination of these pronutrients together with essential vitamins and amino acids, improves the overall condition of the breeders and, therefore, their reproductive performance.

Field trials have shown that the use of Premium AVAL in trout improves egg hatchability rate by 100% in trout.

• AVAL Premium is a natural product, developed and marketed by Biovet S.A.-

 

Bibliography:

• Alabal-k, Bir & G-kku-a-, -leletmesindeki & Dam-zl-klar-n-n, Alabal-&Performans-, -retim & Bir, Azerine & Mustafa, Al-am & Ozgur, Me & Bayir, smail. (2013). A Research on Reproduction Performance for Broodstocks of Rainbow Trout in A Fish Farm.
• Borrell, Use of plant-based pronutrients in veterinary medicine, Royal Academy of Veterinary Sciences (RACVE), available at: http://www.racve.es/publicaciones/uso-de-pronutrientes-de-origen-natural-en-veterinaria/
• Maguregui, Ekaitz. (2020). The immune system of fish: improves aquaculture production through immunity. VeterinariaDigital.com
• Schreck, C.B., Contreras-Sanchez, W., & Fitzpatrick, M.S. (2001). Effects of stress on fish reproduction, gamete quality, and progeny-Oregon Agricultural Experiment Station Technical Report Number 11578. Reproductive Biotechnology in Finfish Aquaculture, 3-24. https://doi.org/10.1016/b978-0-444-50913-0.50005-9