This study evaluated the effects of organic trace mineral supplementation on growth performance, antioxidant indices, mineral status, and diarrhea incidence in dairy calves raised in arid climates. Twenty-five male Holstein calves were randomly assigned to five dietary treatments for 21 days, as follows: (1) control group (no organic mineral supplementation), (2) copper-methionine (Cu-Met) supplemented diet, (3) zinc-methionine (Zn-Met) supplemented diet, (4) manganese-methionine (Mn-Met) supplemented diet, and (5) Zn-Met + Cu-Met + and Mn-Met in a premix supplemented diet. Mineral supplementation had no effect on final body weight or average daily gain. However, the concentrations of Zn, Cu, and Mn significantly increased (p < 0.01) in blood and feces of treated animals. The highest blood concentrations of Zn and Mn were observed in calves receiving Zn-Met, while Mn-Met supplementation significantly influenced blood Cu levels. The highest Zn excretion was recorded in calves receiving the organic mineral premix, whereas the highest Mn and Cu excretion was observed in the Cu-Met group. Additionally, mineral supplementation enhanced total antioxidant capacity and superoxide dismutase activity in plasma samples (p < 0.01). These findings suggest that organic mineral supplementation could be an effective strategy to improve mineral bioavailability and support the health of dairy calves during early life in arid climates.

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