Iron Deficiency in Stabled Dutch Warmblood Foals

Forty‐three Dutch Warmblood foals were divided at random into 3 rearing groups immediately after birth: a box‐rest group, a box‐rest with exercise group, and a pasture group. All stabled foals (box‐rest and exercise groups) were fed freshly cut grass harvested from the same pastures on which the pasture group foals were grazing. Blood samples were obtained monthly for CBC and biochemical analyses. At 1–3 months of age, the foals at pasture were active but the foals in the box‐rest and exercise groups were listless. Mean hemoglobin concentrations, PCVs, blood iron concentrations, and saturation of total iron binding capacity were significantly lower ( P < .05) in the box‐rest group (11.3 ± 1.2 g/dL, 33 ± 3%, 123 ± 67 μg/dL, and 18 ± 9%) and the exercise group (11.6 ± 1.5 g/dL, 34 ± 4%, 101 ± 61 μg/dL, and 15 ± 10%) compared with the pasture group (14.0 ± 0.8 g/dL, 42 ± 3%, 212 ± 67 μg/dL, and 32 ± 10%). Oral supplementation of iron to all foals resulted in significant increases in the values of these variables in the box‐rest group and exercise group at 4–5 months of age, and the stabled foals were as active as the foals at pasture. In the pasture group, no significant changes occurred. Management practices clearly influence the iron state in young growing foals from 1 to 3 months of age, and although not a frequent cause of anemia in the horse, an absolute deficit of body iron may occur in stabled foals fed freshly cut grass.