Effect of dietary iron sources on Cyprinus carpio var. specularis and Lactuca sativa var. ramosa hort in aquaponic system

Abstract

In order to explore the dietary iron sources on Cyprinus carpio (12.54 ± 1.65 g) and Lactuca sativa in aquaponic system, three semi-purified diets with iron contents of around 120 mg/kg were prepared: S-120 (ferrous sulfate); C-120 (ferrous citrate); and G-120 (ferrous glycinate). The results of 2 months trail showed that: (1) The final weight and weight gain of juvenile mirror carp in the C-120 and G-120 group showed a significant increase compared to those in the S-120 group (P < 0.05), and the feed conversion ratio in G-120 group significantly lower than the S-120 group (P < 0.05). (2) The fish muscle and whole-body iron content in the S-120 group were significantly lower than that in the C-120 group and G-120 group (P < 0.05). (3) The ∑n-3PUFA (mainly C22:6n-3) content of fish muscle in G-120 group were significantly higher than S-120 and C120 group (P < 0.05). (4) The liver superoxide dismutase activities in the G-120 and C-120 groups were significantly higher than the S-120 group (P < 0.05). The blood hematocrit level in the C-120 group was significantly higher than that in the S-120 group (P < 0.05). (5) The height, number of leaves, yield and chlorophyll of lettuce in the S-120 group were significantly higher compared to the G-120 group (P < 0.05). (6) The nitrogen utilization of fish in G-120 and C-120 groups was significantly higher than that in S-120 group (P < 0.05), and the nitrogen utilization of vegetables in S-120 and C-120 groups was significantly higher than that in G-120 group (P < 0.05). The total nitrogen utilization rate of S-120 group was higher than that of G-120 and C-120 groups (P < 0.05). Therefore, we suggested to use ferrous citrate as the iron source in feed of mirror carp to enhance the yield of fish and vegetables in the aquaponic system.