Effect of dietary supplementation with yeast Saccharomyces cerevisiae on skin, serum and liver of gilthead seabream (Sparus aurata L).

The effect of dietary supplementation with Saccharomyces cerevisiae on gilthead seabream (Sparus aurata L.) was studied. Four replicates of fish (n = 6) were fed with a commercial diet containing 0 (control, no yeast added) or 10 mg per kilogram of heat-killed (30 min, 60°C) S. cerevisiae. After 4 weeks, half of the fish (two replicates) were injured and continued with the same diet. At 3 and 7 days post-wounding, samples of blood, skin mucus, skin and liver were obtained from each fish. The results showed that calcium concentrations were significantly higher (with respect to control fish) in the serum from fish sampled at 3 days post-wounding, whereas antioxidant enzymes in the skin mucus were altered after wounding (at both 3 and 7 days). Histological analyses revealed oedema, signs of inflammation and white cell recruitment together with a reduction in the epidermis layer in the wounded regions of fish fed control diet. Yeast supplementation did not change growth performance and helped maintain the normal serum calcium concentrations in wounded fish. Furthermore, a reduction in inflammation around wounds in the animals fed yeast with respect to that fed control diet was evident in the histological study. Furthermore, increased levels of stress-related gene expression in liver and skin from wounded fish were obtained. Overall, yeast supplementation seemed to be a functional and appropriate dietary additive to improve skin recovery reducing the stress resulting from wounds.