Responses to Excess Dietary Magnesium as Affected by Experimental Eimeria acervulina Infection or by Dietary Ammonium Chloride Ingestion in the Chick

Three experiments were conducted to investigate the effect of experimental Eimeria acervulina infection on excess Mg ingestion in the chick and to investigate the effect of NH4Cl addition to the diet on the coccidiosis × Mg interaction. Two Mg sources were evaluated, MgO and MgSO4·7H2O. Gain, efficiency of feed utilization, bone ash percent (BAP), bone Ca and duodenal pH were lower in coccidiosis-infected chicks than in uninfected chicks. However, bone P and bone Mg levels were higher as a result of the coccidial infection. Bone Mg levels were higher and bone Ca levels and BAP were lower in chicks fed excess dietary Mg, either as the oxide or sulfate forms. Gain and feed efficiency of chicks fed excess Mg, as MgO but not as MgSO4·7H2O, were lower than in chicks fed the basal level of Mg. Coccidiosis × Mg interactions were observed in bone Mg and bone Ca concentration data; bone Mg uptake was greater when high dietary Mg and the coccidial infection were in combination. In some instances, a similar interactive effect was observed in bone Ca concentration data; bone Ca loss tended to be greater as a result of the combination of high dietary Mg and the coccidial infection.