Relationship of iron administration to susceptibility of newborn pigs to enterotoxic colibacillosis.

To determine whether supplemental iron (Fe) administration to newborn pigs reared in concrete pens not only prevents anemia, but renders the pigs more susceptible to Escherichia coli-induced diarrheal disease, pigs were given a large or a small dose of Fe IM or orally before or after challenge exposure with E coli. The controls were challenge-exposed pigs not given Fe and pigs not challenge exposed (Fe-treated and nontreated groups). Although the mortality of the pigs challenge exposed with E coli and administered a large oral dose of Fe shortly after birth was greater than that of the challenge-exposed pigs given no Fe, differences in mortality were not noted between any of the groups tested when the Fe was injected IM. The Fe-treated survivors had severe diarrhea (oral Fe administration) or mild diarrhea (IM Fe administration) for longer periods than did the nontreated survivors. All challenge-exposed pigs treated with a large dose of Fe gained less weight than the nontreated pigs during the diarrheal period and for several days thereafter. Beyond this time period, the weight gain of the Fe-treated pigs was substantially greater than that of their nontreated littermates; the weight gain of the pigs given a small dose of Fe was intermediate. Hemoglobin and hematocrit values of the pigs shortly after birth and weekly thereafter revealed that within 2 weeks, both sets of values from the pigs treated with a large dose of Fe were within acceptable laboratory limits and substantially greater than the values obtained for the nontreated pigs, which were severely anemic.