Effects of lead contamination in feed on laying performance, lead retention of organs and eggs, protein metabolism, and hormone levels of laying hens

Five hundred seventy-six Hy-Line Brown hens, 40 wk old, were randomly allotted to 4 groups, each of which included 4 replicates of 36 hens. The groups were given a basal corn-soybean meal diet supplemented with 0 (control group), 15, 30, and 60 mg/kg of lead. No differences were observed for laying rate and FCR among the treatments, whereas adding 15, 30, and 60 mg/kg of lead decreased ADFI. Lead concentrations in albumen, yolk, liver, kidney, oviduct, and ovary of the treatment groups were higher than those of the control group. The addition of lead at 60 mg/kg resulted in increased levels of serum urea nitrogen, urea acid, and glutamic oxalacetic transaminase activity. Levels of serum progesterone, follicle-stimulating hormone, and luteinizing hormone in the control group were significantly higher than those of the treatment groups. In conclusion, we indicate that lead concentrations in tissues and eggs have a positive correlation with dietary lead levels, and lead may affect the reproductive performance of hens by reducing the levels of endocrine hormones.