Impact of Dietary Supplemental Chromium and Zinc on the Performance of Laying Hens, Egg Quality, and Blood Chemistry.

This study evaluated the individual and interactive effects of dietary chromium (Cr) and zinc (Zn) supplementation on productive performance, egg quality, and blood biochemical parameters in Lohmann LSL-Lite laying hens. A total of 216 hens (42 weeks old) were allocated to a 3 × 2 factorial arrangement with three dietary Cr levels (0, 3, and 6 mg/kg) and two Zn levels (0 and 40 mg/kg) over a 12-week period. Chromium supplementation significantly affected feed conversion ratio (FCR), hen-day egg production (EP), and egg mass (EM), with hens receiving no supplemental Cr exhibiting higher EP and EM than those supplemented with 3 or 6 mg/kg Cr (p = 0.001). Feed intake (FI) was not influenced by either Cr or Zn supplementation (p > 0.05). Both Cr and Zn significantly affected shell thickness (p = 0.0259 and p = 0.0026, respectively), with Zn increasing and Cr decreasing shell thickness. Chromium supplementation also reduced shell weight (p = 0.0138). A significant Cr × Zn interaction was observed for yolk color (p = 0.0429), with the highest values recorded in hens fed 40 mg/kg Zn combined with 3 mg/kg Cr. Blood albumin concentrations increased with increasing dietary Cr and Zn levels (p = 0.0001), whereas blood triglyceride concentrations decreased following Zn supplementation (p = 0.0490). Zinc supplementation increased blood Zn concentrations (p = 0.0267), while Cr supplementation reduced blood Cr concentrations (p = 0.0001). In conclusion, dietary Cr supplementation at the tested levels did not improve laying performance and, in some cases, reduced EP and EM, whereas Zn supplementation enhanced certain egg quality traits and improved blood biochemical profiles. Furthermore, the interaction between Cr and Zn influenced yolk color and blood Cr concentrations.