The Atlantic salmon ( Salmo salar) is a prominent species in aquaculture, and optimizing its growth and health is of paramount importance to the aquaculture industry. Brewer’s yeast is a known source of essential nutrients and bioactive substances such as β-glucans, mannan-oligosaccharides, and nucleotides which can potentially enhance the growth and overall health of aquatic species. This study investigates the impact of incorporating two distinct commercial brewer’s yeast additives , an autolysed brewer’s yeast (ABY) and a soluble dried yeast extract (SDYE), manufactured by Leiber GmbH into the diet of Atlantic salmon juveniles on their performance and mucosal health.
A 9 -week feeding trial was conducted in a cold freshwater indoor recirculatory aquaculture system (RAS) with Atlantic salmon juveniles (37.08g) at the University of Plymouth . Three isonitrogenous and isocaloric diets were formulated to meet the known nutrient requirements of Atlantic salmon (Table 1). The control diet (T1) had no brewer’s yeast additive while the other two diets, T2 and T3, were supplemented with 0.25g/100 g of autolysed brewer’s yeast or soluble dried yeast extract, respectively. The fish (20 fish/70 L tank) were fed one of the three diets (n = 3 tanks ) at 1 % of body weight per day. Water quality parameters were monitored throughout the trial. At the end of the feeding trial, skin and intestinal samples were taken for intestinal assessments using light and electron microscopy , expression of immunoregulatory genes, haematology, and 16S rRNA metabarcoding.
The result of the skin histology revealed that t here was a significant enhancement (p<0.05 ) of goblet cell abundance through dietary supplementation in the fish fed T2 (18.22±2.48 /200µm) compared to the T1 (14.56±2.85 /200µm) and T3 (14.44±2.66 /200µm) groups.
Ongoing analysis of histological parameters of the intestinal samples , expression of key immunoregulatory genes , haematology, and a 16S rRNA metabarcoding analysis of intestinal samples.