Potassium diformate in the diet of sterlet sturgeon ( Acipenser ruthenus ): Zootechnical performance, humoral and skin mucosal immune responses, growth‐related gene expression and intestine morphology

Abstract

This study evaluated the dietary effect of potassium diformate (KDF) on growth performance, body composition, humoral and skin mucosal immune responses, growth-relevant gene expression and intestine histomorphology in sterlet sturgeon. Sterlet fingerlings (N = 270; 6.86 ± 0.14 g) were scattered randomly into 18 tanks (six experimental diets in triplicate groups) and fed with incremental levels of KDF including 0 (control), 3 (KDF3), 6 (KDF6), 9 (KDF9), 12 (KDF12) and 15 (KDF15) g kg−1 for 70 days. The groups fed with KDF6 and KDF9 diets presented significantly higher growth indices and whole-body protein content, whereas the lowest feed conversion ratio was measured in these treatments compared with other groups (p < .05). Total immunoglobulin, lysozyme activity and total protein levels in the serum and skin mucus samples were increased by increasing the levels of KDF, and the highest values were obtained in KDF9. The expression levels of growth hormone, ghrelin, and insulin-like growth factor-I genes were notably upregulated in KDF9 compared with the control, KDF3 and KDF15 groups. The villus length and width of hind-gut were more than doubled in KDF9 treatment compared with the control group (p < .05). These results showed that the application of KDF in sterlet diet had the potential to achieve high overall performance, and also, the optimum inclusion level of KDF ranged from 8.48 to 8.83 g kg−1 based on the second-order polynomial analysis models.