Effects of Different Iron Sources on the Growth and Iron Concentrations of Tissues, Organs, and Blood of Genetically Improved Farmed Tilapia (Oreochromis niloticus)

Abstract

A 70-day feeding trial was conducted to elucidate the effects of different iron (Fe) sources on growth and Fe concentrations in the tissues, organs, and blood of genetically improved farmed tilapia (Oreochromis niloticus). Five experimental diets (45.0% crude protein, 3.7% crude lipid) with the same Fe concentration (100 mg/kg of feed) were formulated from different Fe sources: ferrous sulfate (FeSO4), ferric chloride (FeCl3), ferrous chloride (FeCl2), ferrous citrate (C6H5FeO7), and iron porphyrin (Fe-porphyrin). The results showed that the percent weight gain (%WG) of fish in the FeCl2 group was the greatest among all five groups (p < 0.05). With %WG as the main indicator, FeCl2 was the most suitable source of dietary Fe for O. niloticus．In the FeCl2 group, the content of Fe in the spleen was significantly greater than that in the C6H5FeO7 group on day 28, and that of the FeSO4 group on day 56. The Fe concentrations in the liver, spleen, gill, vertebra, blood, whole intestine, and dorsal white muscle of O. niloticus were not significantly affected by different dietary sources of Fe on day 70. There were only slight dynamic changes to the Fe content of tissues and organs during the experimental period. The Fe contents in different tissues and organs were as follows: spleen > mid-hind intestine > liver > gill, muscle, foregut > spine. The spleen had the highest Fe content in all groups on day 70. These results suggest that FeCl2 is the best source of dietary Fe for O. niloticus with %WG as the main indicator.