Requirement and Utilization of Iron by the Baby Pig

Hemoglobin and weight-gain data from three experiments indicate that the minimum iron requirement of baby pigs, fed fortified cows’ milk, up to 60 days of age was approximately 60 ppm of the dry matter intake. Estimates of the synthesized hemoglobin, made from these data and radioactivity data, indicate that utilization of the iron at the minimum requirement level was approximately 30%. Making baby pigs anemic (about 6 gm Hb/100 ml blood) by depleting them of iron before initiating iron feeding did not increase iron utilization. Specific activity data of blood, liver, spleen, kidney and bone marrow suggested that at the critical end of iron deficiency, tissue iron needs took precedence over hemoglobin iron need. Once this minimum tissue need was met, however, absorbed iron appeared to be incorporated directly into hemoglobin without equilibrating with tissue iron.