Effects of Reduced-Level Coated Inorganic Compound Trace Minerals on Breeder Hen Performance, Eggshell Quality, Antioxidant Status, and Progeny Development Compared with an Inorganic Premix

This study evaluated the effects of reduced inclusion levels of coated inorganic compound trace elements as a reduced substitution for uncoated inorganic trace elements in layer breeder diets. A total of 360 Hy-Line Brown layer breeder hens were randomly assigned to three groups, with six replicate pens of 20 hens per group: control group A (inorganic trace elements), group B (500 mg/kg coated inorganic compound trace elements), and group C (1000 mg/kg coated inorganic compound trace elements). Compared with the control, the coated trace element groups significantly increased the laying rate, eggshell strength and yolk color, and decreased the cracked egg rate and feed-to-egg ratio (p < 0.05). Group B had a lower cracked egg rate and a higher egg shape index than group C. Regarding eggshell ultrastructure, group B had a greater effective layer thickness and proportion and a lower mammillary layer thickness and proportion (p < 0.05), while group C presented increased mammillary width. The coated trace elements increased the deposition of Mn, Zn, and Se in eggs and increased serum GSH-Px and Cu-Zn SOD activities and the T3 concentration. No significant differences in hatching performance were observed among the groups. For progeny, groups B and C had higher birth weight, pectoralis muscle weight, and liver weight, as well as improved serum antioxidant indices and intestinal morphology (p < 0.05). The mRNA expression of intestinal tight junction genes was upregulated in group C (p < 0.05) and showed a modest increase in group B. In conclusion, the coated inorganic compound trace elements, when used at reduced inclusion rates, replaced the conventional uncoated inorganic premix without compromising production performance and improved several performance outcomes. The 500 mg/kg inclusion level provided the most balanced improvements in breeder performance and progeny quality while reducing feed costs. These findings suggest that coated mineral technology may sustain productivity at a substantially lower mineral input and may benefit progeny by increasing egg mineral deposition and supporting intestinal development, thereby providing a more sustainable mineral-feeding strategy for breeder hens.