A study carried out by the Chilean Interdisciplinary Center for Aquaculture Research (INCAR), together with ACUAIM and ACUANATIVA, validated the use of L-END, a 100% botanical functional additive, against sea lice (Caligus rogercresseyi) in salmon. The study found that the additive protects Atlantic salmon against sea lice infestation when added to feed, modulating relevant genes for the development of the parasite as well as others involved in salmon mucosal immunity.

“The control strategies for sea lice in Chile have focused on the use of drugs administered orally or bath treatments. Phytogenic additives (100% standardized botanicals) incorporated in fish feeds have been established as an alternative to the use of drugs as an environmentally friendly prophylactic approach, stimulating the immune response, preventing infectious diseases, improving tolerance to stress and general health of the fish and, therefore, optimizing growth and/or production efficiency with less environmental impact. L-END is a phytogenic additive formulated and developed to establish strategies for the integrated management of sea lice parasitosis, through its incorporation in fish feeds,” explained associate researcher from INCAR and Laboratory of Immunology and Stress of Aquatic Organisms of the Austral University of Chile, Alex Romero.

The study found that aquafeeds with 1 kg/ton of the phytogenic additive for a period of 14 days significantly reduced the parasite load in Atlantic salmon (5.7 Caligus/fish) compared to the control diet (12.8 Caligus/fish), with a percentage of efficacy on total Caligus of 55.9% compared to the control group.

“This effect would be associated with the modulation of the expression of key genes in the molting and reproductive processes of the parasite. It was reflected in significant differences in the thickness of the ovigerous capsule in females and alterations in the development of the parasites, evidenced in the changes in the proportion of stages at the end of the trial, with a predominance of chalimus IV in the case of the fish fed with the additive,” researchers said. 

At the same time, the inclusion of the additive in the diet significantly increased the expression of fish mucosal immunity genes, which suggests the positive effect of this functional diet on the skin immunity of Atlantic salmon.