Bioavailability of Different Sources of Dietary Iron Fed to Pitman-Moore Miniature Pigs

Prevention of Fe deficiency was studied with eight Pitman-Moore miniature pigs in each of seven groups. From 5 to 33 days of age the animals received identical cereal-milk diets except for Fe content: diet 1, no added Fe (8 ppm); diet 2, ferrous sulfate; diet 3, catalytically reduced Fe; diet 4, electrolytic Fe powder; diet 5, sodium Fe pyrophosphate; diet 6, ferripolyphosphate powder; diet 7, disodium Fe EDTA. Diets 2–7 provided 64 to 69 ppm of supplemental Fe. Body weight and gain in weight of pigs fed diet 1 did not differ significantly from those of pigs fed diets 2–7; however, gain in body weight between 21 and 28 days of the feeding trial was significantly less in pigs fed diets 1 or 5 than in pigs fed diets 2, 6 or 7. Final Hb and hematocrit values were less than initial values in pigs fed diets 1, 3, 4 and 5. The change in Hb, hematocrit and total Hb Fe of pigs fed diets 1, 3 or 5 differed significantly from those of pigs fed diets 2, 6 or 7. The efficiency with which supplemental Fe was incorporated into Hb ranged between 27 and 30% in pigs fed diets 2, 6 or 7, was 21% in pigs fed diet 4 and approximately 10% in pigs fed diets 3 or 5. Pigs fed diet 1 differed from those fed the other diets in the following manner: liver weight was significantly less; weights of spleen, heart and kidney were significantly greater; less of an intraperitoneal injection of 59Fe was retained in Hb and in organs; of the retained 59Fe, significantly less was found in Hb and significantly more in tissues. Fe status as measured by Hb and hematocrit appeared to be inversely correlated with 59Fe concentration in liver, spleen, kidney and heart.