The modulatory effects of Cyberlindnera jadinii on growth performance, health, welfare, and product quality of Atlantic salmon (Salmo salar): A large-scale field experiment

A 26-week trial was conducted to evaluate the effects of Cyberlindnera jadinii on post-smolt Atlantic salmon (2.310 ± 0.015 kg). Diets containing 0 (Diet 1, D1), 6 (Diet 2, D2), 12 (Diet 3, D3), and 18% (Diet 4, D4) C. jadinii were fed to duplicate cages. Decreased growth rate relative to D1 (p = 0.0444) was only observed in fish fed D4. The apparent digestibility coefficients of crude protein, crude lipid, and gross energy decreased (p < 0.01) with an increasing level of C. jadinii in the diet. Fish fed D1 or D2 had higher odds of high scores for gaping of the belly and wounds, respectively, relative to fish fed D4. The expression of il-8 , tgfb , and il-10 in the distal intestine (DI) was significantly higher in fish fed D4 compared to fish fed D1 or D3 (p ≤ 0.05). The increased expression of tgfb and il-10 was correlated with il-8 (p ≤ 0.05). Also, there was a reduction in alpha-diversity in fish fed C. jadinii in digesta- and mucus-associated microbiota, while beta-diversity in digesta-associated microbiota showed a clear separation of fish fed D1 from the fish fed C. jadinii . A greater percentage area of the simple fold with MHCII and CD3 positive cells was reported in the DI of fish fed D4 compared to D1. Overall, this study suggests that an inclusion level of up to 12% C. jadinii is possible in diets for Atlantic salmon reared in seawater cages, supporting growth, health, welfare, and product quality of fish similar to that of a commercial-like control diet. • C. jadinii can be included at up to 12% in diets for Atlantic salmon in seawater. • C. jadinii did not adversely affect fish welfare or product quality. • Inclusion of 18% C. jadinii modulated the immune response in the distal intestine. • C. jadinii modulated the digesta- and mucosa-associated microbiota.