A team of Spanish researchers, together with Tecnovit-Farm Faes, demonstrated that it is possible to reduce the incidence of the branchial ectoparasite Sparicotyle chrysophrii in sea bream (Sparus aurata) through the use of nutritional strategies based on the incorporation of essential oils in the diet.
Researchers tested a microencapsulated feed additive composed of essential oils of garlic, carvacrol and thymol (AROTEC-G) to evaluate its protective effect on gills. According to Enric Gisbert, head of IRTA’s Aquaculture program, “fish were fed for 65 days with a feed containing the additive and were subsequently exposed to a challenge by cohabiting with parasitized fish for another 39 days.” A transcriptomic analysis (using microarrays) was carried out followed by functional gene analysis, which revealed a pro-inflammatory immune response of the branchial tissue mediated mainly by acidophilic granulocytes, sustained by both antioxidant and anti-inflammatory responses.
These results were contrasted by a histochemical study of the gills that also showed an increase in carboxylated glycoproteins rich in sialic acid in the mucous and epithelial cells of fish fed with essential oils. “These results suggest the promotion of the defense mechanism of the mucosa partly through the modulation of its mucin secretions,” added Gisbert.
The results of the challenge by cohabitation supported the transcriptomic and histological results obtained from the nutritional test since a significant reduction of 78% in the total abundance of S. chrysophrii and a decrease in the prevalence of most of the parasite stages were observed in fish fed the additive.
The results of this study suggest that the microencapsulation of the essential oils of garlic, carvacrol and thymol is an effective feeding strategy with proven antiparasitic properties against S. chrysophrii. “This is an excellent example of joint research with an important presence of the private sector, being a clear success case in which academia and industry have combined their capacities and knowledge to face a problem, offering a concrete solution to a situation that has been affecting gilthead seabream’s cage culture for years in the Mediterranean,” said Gisbert.
These results have been obtained in the frame of the JACUMAR project “Nutritional strategies for the improvement of productive performance: use of functional feed and diets in aquaculture,” financed by MAPAMA and FEMP funds.
Download the study here.
