Submitted to: Journal of the World Aquaculture Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 8, 1997
Publication Date: N/A
Interpretive Summary: Iron is an essential element for growth and well-being of all higher animals including fish due to its importance in cellular respiration and mitosis. Although fish can absorb soluble iron from the water, feed is considered as the major source of iron for fish due to low concentrations of soluble iron in natural waters. Dietary iron requirements for optimum growth and hematological values have been determined of channel catfish using iron sulfate as the course of dietary iron. Recent studies with animals and fish, however, have shown that chelation of minerals to amino acids may increase their absorption rate. Thus, this study was conducted to determine the dietary iron requirement for channel catfish fingerlings using iron methionine (FeM) as the dietary iron source and to compare the bioavailability of FeM and iron sulfate (FeS) using a purified diet. Results of this study showed that 5 mg of supplemental iron/kg diet from FeM was adequate for good growth and survival. However, a supplemental level of 20 mg iron/kg diet from either FeM or FeS or a total 30 mg iron/kg diet was needed for optimum hematological value and prevention of hypochromic microcytic anemia in channel catfish, indicating that both sources of iron are equally available.
Technical Abstract: The dietary iron requirement for normal growth and optimum hematological values and bioavailability was determined for channel catfish fingerlings using egg-white based diets supplemented with 0, 5, 10, 20, 60, and 180 mg iron/kg from iron methionine (FeM) or 20, 60, and 180 mg iron/kg from iron sulfate (FeS). The basal diet which contained 9.2 mg iron/kg was fed to channel catfish fingerlings (8.5 g) in triplicate flow-through aquariums to satiation twice daily for 8 weeks. Fish fed the basal diet without iron supplementation exhibited poor growth throughout the 8-week period. Fish fed iron-supplemented diets did not differ with regard to final weight gain. Survival, feed conversion, total blood cell count, mean corpuscular hemoglobin concentration, serum iron, total iron biding capacity, and transferrin saturation were not significantly affected by dietary iron level. Hemoglobin, hematocrit, mean corpuscular hemoglobin, and mean corpuscular volume were significantly lower in fish fed the basal diet. These values were also consistently lower for fish fed diets with 5 and 10 mg iron/kg from FeM. However, differences were not always significant. Results of this study indicate that supplementation of 5 mg iron from FeM was sufficient for growth. However, a supplemental iron level of 20 mg/kg diet or a total iron level of 30 mg/kg of diet was need for optimum hematological values. Iron methionine and FeS were equally effective in preventing anemia in channel catfish.