IRON METHIONINE AND IRON SULFATE AS SOURCES OF DIETARY IRON FOR CHANNEL CATFISH ICTALURUS-PUNCTATUS

The dietary iron requirement for normal growth and optimum hematologic al values and bioavailability was determined for channel catfish Ictal urus punctatus fingerlings using egg-white based diets supplemented wi th 0, 5, 10, 20, 60, and 180-mg iron/kg from iron methionine or 20, 60 , and 180-mg iron/kg from iron sulfate. The basal diet which contained 9.2-mg iron/kg, 34% crude protein and 3.1 kcal of digestible energy/g was fed to channel catfish fingerlings (8.5 g) in triplicate flow-thr ough aquariums to satiation twice daily for 8 wk. Fish fed the basal d iet without iron supplementation exhibited poor growth throughout the 8-wk period. Fish fed iron-supplemented diets did not differ with rega rd to final weight gain. Survival, feed conversion, total blood cell c ount, mean corpuscular hemoglobin concentration, serum iron, total iro n binding capacity, and transferrin saturation were not significantly affected by dietary iron level. Hemoglobin, hematocrit, mean corpuscul ar hemoglobin, and mean corpuscular volume were significantly lower in fish fed the basal diet. These values were also consistently lower fo r fish fed diets with 5 and 10-mg iron/kg from iron methionine. Howeve r, differences were not always significant. Results of this study indi cate that supplementation of 5-mg iron from iron methionine was suffic ient for growth. However, a supplemental iron level of 20-mg/kg diet o r a total iron Level of 30-mg/kg of diet appeared to be needed for opt imum hematological values. Iron methionine and iron sulfate were equal ly effective in preventing anemia in channel catfish.