Dietary zinc, manganese and copper combination in sulphate or amino acid chelate forms impacts laying performance and intestinal morphology in late-phase laying hens.

This study was designed to evaluate the effect of zinc (Zn), manganese (Mn), copper (Cu) combination supplementation in different forms on laying performance, intestinal morphology and antioxidant capacity of laying hens between 64 and 75 weeks of age. A total of 600 Lohmann White layer hens at 64 weeks of age were assigned into 5 treatment groups, with 3 replicates, consisted of the control diet, control group (no supplementation of Zn, Mn and Cu; CG), supplementation of calcium carbonate (CaCO₃) as a carrier of Zn, Mn and Cu sulphate (CCS), sulphate form of Zn, Mn and Cu combination (SF), glycine chelated of Zn, Mn and Cu combination (GC), and Zn + Mn - methionine (Met) chelated, Cu - lysine (Lys) chelated (MLC) group. Hen-day egg production tended to be higher in the GC and MLC groups during experimental period (P < 0.001). It changed between 79.7% and 83.4% in GC and MLC groups between 64 and 75 weeks of age. At 69 and 75 weeks of age, the highest value of egg weight was observed in the GC group with values of 66.8 g and 67.1 g, respectively (P < 0.001). The supplementation of MLC caused an enhancement in villus size, including villus height and surface area, in both duodenum and ileum (P < 0.001). In the duodenum, the villus height was found to be the highest with a value of 2583.2 μm in the CCS group, whereas the villus width was higher in SF (349.9 μm) and MLC (391.7 μm) groups (P < 0.001). In the jejunum, SF caused a stimulation effect for villus efficiency, by increasing villus height (2512.6 μm), villus apparent surface area (723680 µm²), crypt depth (291.1 μm), and VH/CD (9.4, P < 0.05). Zn, Mn and Cu combination in glycine chelated and methionine-lysine chelated forms caused an increment in height of villus in the ileum part of small intestine (1421.7 μm in GC and 1388.0 μm in MLC) when compared other supplementation groups (P < 0.001). In conclusion, it could be suggested that egg production could be improved by 4.3% with supplementation of Zn + Mn-Met and Cu-Lys chelate compared to the commercial diet.