Effects of a dietary anionic alkali mineral complex in juvenile olive flounder (Paralichthys olivaceus) during low water temperature season

Abstract

This study was conducted to investigate the effects of different supplementary levels of an anionic alkali mineral complex (AAMC) containing sodium metasilicate, potassium carbonate, sodium carbonate, sodium tetraborate, sodium chloride, sodium thiosulfate, silver nitrate and sucrose on growth, innate immunity and disease resistance of juvenile olive flounder (Paralichthys olivaceus) during the low temperature season (15.0 ± 2.6 ºC). The control diet was a commercial feed and 0.5%, 1% and 2% of AAMC were sprayed to the control diet to prepare experimental diets (Control, MC-0.5, MC-1.0, and MC-2.0). Quadruplicated groups of juvenile olive flounder (9.11 ± 0.04 g) were distributed in a flow-through system as 45 fish per tank and fed one of the experimental diets to apparent satiation twice a day (08:30 and 16:30 h) for 12 weeks. The dietary supplementation of AAMC improved the feed utilization of fish. Growth performance of fish was significantly improved by feeding MC-2.0 diet compared to control group. Fish fed MC-2.0 diet showed significantly higher blood hemoglobin level compared to the control. Gut morphology of fish was improved by dietary AAMC. Innate immunity and antioxidant capacity of fish were also significantly improved by dietary AAMC. Apparent digestibility coefficient of dry matter was significantly increased in MC-1.0 diet, while protein digestibility was significantly higher in both MC-1.0 and MC-2.0 diets. The cumulative mortalities of challenged fish fed MC-1.0 and MC-2.0 diets were significantly reduced. In conclusion, the dietary supplementation of 2% AAMC significantly improved the growth performance, innate immunity, diet digestibility and disease resistance against Edwardsiella tarda in juvenile olive flounder reared in low water temperature season.