Effects of feeding whole milk, whole milk with iron supplementation or milk replacer on hematological parameters, plasma enzymes, and copper status in Holstein calves

The objective was to determine the effects of three different milk feeding strategies with varying levels of iron (Fe) and copper (Cu) on calves’ hematocrit (Hct), hemoglobin (Hb), Cu status and plasma enzyme markers. The treatments were whole milk (CONTROL, <4 mg Fe per day, <1 mg Cu per day in milk), whole milk supplemented with iron (IRON, 110 mg Fe per day,<1 mg Cu per day) and milk replacer (MR, 152 mg Fe per day, 14.3 mg Cu per day). At birth Hct was 30.4 ± 0.7% in average. CONTROL had decreasing Hct levels with nadir in week 5 of 22.5 ± 0.8%. IRON and MR had increasing Hct levels, with zenith at 38.4 ± 1.3% in week 5 and 34.7 ± 0.8% in week 2, respectively. Hepatic Cu concentrations were greater (636 ± 46 mg/kg DM) in MR compared with IRON and CONTROL (172 and 163 ± 46 mg kg DM, respectively).