Toxicological Effects of Mercury Chloride on Laying Performance, Egg Quality, Serum Biochemistry, and Histopathology of Liver and Kidney in Laying Hens.

The objective of this study was to determine the effects of mercury chloride (HgCl ₂ ) on laying performance, egg quality, hepatic and renal histopathology, and serum biochemical profiles in laying hens. A total of 768 Hy-line brown laying hens aged 40 weeks were randomly allocated to four groups (8 pens per group and 24 hens per pen). The concentrations of mercury (Hg) in four groups were 0.280, 3.325, 9.415, and 27.240 mg/kg. Results revealed that dietary Hg could significantly reduce laying performance (P < 0.05) and egg quality (P < 0.05) and was dose-dependently deposited in albumen, yolk, eggshell, and whole egg. Meanwhile, the thicknesses of palisade layer, mammillary layer, and total layer, and the percent of palisade layer were significantly decreased (P < 0.05), while the percent of mammillary layer was sharply increased (P < 0.05) in eggshell. In addition, with increasing dietary dosage of Hg, accumulation of Hg in viscera was significantly increased (P < 0.05), and histopathological damages in liver and kidney were more and more severe. Serum alanine aminotransferase, aspartate aminotransferase, and globulin were significantly increased (P < 0.05), while serum albumin and albumin to globulin ratio were significantly decreased (P < 0.05) in 27.240 mg/kg Hg group. Blood urea nitrogen, uric acid, and creatinine were significantly increased (P < 0.05) in 3.325, 9.415, and 27.240 mg/kg Hg groups. These results suggested that dietary HgCl ₂ could reduce laying performance and egg quality with hepatic and renal function disorders in laying hens.