Comparison of Hydroxychloride Versus Oxide and Sulfate Sources of Manganese, Zinc, and Copper in Rearing Diets on Pullet Growth, Tibia Traits, and Egg Production and Eggshell Quality in ISA Brown Hens up to 50 Weeks

(1) Background: this study compared hydroxychloride and traditional oxide/sulfate sources of zinc (Zn), manganese (Mn), and copper (Cu) in ISA Brown pullet diets, focusing on growth, tibia strength, egg production, and eggshell quality. (2) Methods: in total, 120 pullets were divided into two groups, each with six replicates of 10 birds, receiving diets with hydroxychloride or oxide/sulfate sources of Mn, Zn, and Cu (65, 50, and 5 mg/kg, respectively) during rearing. At 16 weeks, 18 pullets per group transitioned to individual cages and were fed a standard diet with Mn-oxide, Zn-oxide, and Cu-sulfate until 50 weeks. (3) Results: pullets fed hydroxychloride minerals exhibited a higher feed conversion ratio (<i>p</i> = 0.023) and a trend toward higher average daily feed intake (<i>p</i> = 0.059) compared to those on oxide/sulfate sources during the rearing phase. During the laying phase, while no significant differences were observed in egg production until 24 weeks, hens previously fed hydroxychloride minerals demonstrated increased average daily feed intake and egg weight from 25 to 50 weeks of age (<i>p</i> < 0.05). (4) Conclusions: rearing diets supplemented with hydroxychloride minerals influenced feed intake and efficiency, with carryover effects that enhanced laying-phase performance.