Effects of dietary vitamin K3 levels on growth, coagulation, calcium content, and antioxidant capacity in largemouth bass, Micropterus salmoides

Abstract

An 8-week feeding trial investigated the optimum dietary vitamin K3 requirements of largemouth bass. A total of 600 healthy fish (12.96 ± 0.07 g) were fed diets containing varying levels of vitamin K3 at 0.78 (K0), 5.80 (K5), 10.82 (K10), 15.84 (K15), and 20.85 (K20) mg/kg with four replicates per level. Results showed that dietary vitamin K3 enhanced growth, with weight gain rate and specific growth rate in K15 trials significantly higher than K0 trials (P < 0.05). No significant difference was observed in the content of crude protein, crude lipid, moisture, ash, and phosphorus in muscle tissue (P > 0.05). However, the supplementation of vitamin K3 significantly contributed to calcium accumulation in muscle tissues and vertebrae (P < 0.05) and increased red blood cell counts (P < 0.05). The blood coagulation time decreased significantly with increasing dietary vitamin K3 from 0.78 to 10.82 mg/kg (P < 0.05) before stabilizing (P > 0.05). The antioxidant capacity was improved with the addition of vitamin K3, which was inconsistent with the changes in malondialdehyde and MK-4 (a form of menaquinone) within liver and serum, suggesting that the toxicity of excessive artificial vitamin K3 may account for this difference. Using regression analysis, the appropriate dietary vitamin K3 levels within a largemouth bass diet was determined to be in the range of 9.93–15.22 mg/kg, which will provide a reference for the preparation of vitamin premix and artificial diet for largemouth bass.