Egg Quality, Serum Parameters, and Bone Characteristics in Late-Phase Laying Hens Supplemented with Zinc, Manganese, and Copper with Sulfate or Amino Acids.

The aim of this study was to determine the effect of different zinc (Zn), manganese (Mn), and copper (Cu) combinations in different forms on egg quality, serum parameters, and bone characteristics in late-phase laying hens. A total of 600 Lohmann White layer hens at 64 weeks of age were divided into dietary groups with three repetitions (n = 40 hens/cage) in each group. The experimental groups were created as follows: control diet (Cont), supplementation of calcium carbonate (CaCO) as a mineral carrier (CaCO), sulfate form of Zn, Mn, and Cu (Sulf); Zn, Mn, and Cu-glycine chelate (Gly); Zn + Mn-methionine and Cu-lysine chelate (Met-Lys). The minerals were supplemented with an amount of 1 kg/ton of feed. The mean value of egg production was higher in both Gly (81.5%) and Met-Lys (81.4%) and the lowest in the Cont group (78.7%, P < 0.01). The eggshell thickness was found to be 0.397 mm in the Gly group and 0.399 mm in the Met-Lys group compared to the Cont (0.388 mm, P < 0.01). The lowest number of lymphocytes (34.6%) and the highest number of monocytes (26.3%) and basophils (7.0%) were observed in the Met-Lys group (P < 0.05). The plasma Zn was found to be the highest in the CaCO group (176.2 µg/dL) and the lowest in the Cont (73.3 µg/dL) and Met-Lys groups (66.3 µg/dL, P < 0.001). The breaking strength and the ash content of the tibia and femur were found to be the highest in the Met-Lys group (P < 0.05). The Met-Lys supplementation could improve egg production, egg weight, and eggshell thickness, provide a hepatoprotective effects, and strengthen the effect for femur and tibia bones in laying hens during the late term of the laying period.