Physical performance of veal calves during chronic iron deficiency anaemia and after acute iron overload.

Treadmill experiments were performed with calves fed milkreplacer (MR) containing 8, 18, 52, or 86 mg of iron (Fe)/kg during the fattening period. Calves walked at 1 m/s for 10 min and then recovered for 15 min. Calves fed 8 and 18 mg of Fe/kg of MR developed severe hypoferraemia and anaemia whereas plasma (PFe) and haemoglobin (Hb) concentration, erythrocyte number (EC) and packed cell volume (PCV) in calves fed 52 and 86 mg of Fe/kg of MR were normal. PFe did not change, whereas Hb, EC, PCV, and blood lactate, heart rate (HR), respiratory rate (RR), respiratory minute volume (VE), fractional oxygen extraction rate (FO2) and O2 consumption (VO2) rapidly increased during walking, and then decreased during recovery. Hb, EC, PCV, partial O2 pressure of blood, FO2, and VO2 were lower, whereas HR, RR, respiratory exchange rate (RER) and blood lactate were higher in calves fed lowest as compared with those fed highest amounts of Fe, while these traits usually were intermediate in other groups. Calves fed 8 mg of Fe/kg of MR were in addition iv injected with FeOH for 3 d before walking. PFe, but not Hb, EC, and PCV, was drastically rised by FeOH. During walking, merely VO2 was improved, but only slightly. In conclusion, adjustments in calves with severe Fe deficiency anaemia were markedly impaired, and barely improved by acute elevation of PFe.