F. Hajiazizi - Department of Animal Science, College of Agriculture and Natural Resources, Razi University, Kermanshah, Iran.
M. Torki - Animal Science Department, Agriculture Faculty of Razi University
M. Habibian - Department of Animal Science, Faculty of Agriculture, University of Kurdistan, Sanandaj, Iran

This study was conducted to evaluate the effects of dietary supplement-ation of rosemary essential oils (REO) and zinc (as zinc sulfate) on performance, egg quality traits, and some serum biochemical metabolites of laying hens. A total of 144 44-weeks-old Lohmann LSL-Lite laying hens were randomly allocated into four treatments, each comprising six replicates of six birds. The first group was served as control and fed a corn-soybean meal based diet without REO or zinc supplement. The other three groups received control diet supplemented with 200 mg/kg REO, 40 mg/kg zinc, or both feed additives together. Supplementation of REO and zinc to the diet had no significant (P > 0.05) effects on egg production, egg weight, egg mass, feed intake, feed conversion ratio, body weight and production of abnormal eggs. Compared with the control, egg shape index was increased (P < 0.05) in laying hens fed dietary supplementation of REO. Birds fed dietary REO supplementation had lower (P < 0.05) serum total cholesterol level compared with the control. However, this effect was not observed by combination of zinc and REO. These results indicate that the diet inclusion of REO had a potential to improve the egg quality traits and serum cholesterol level in laying hens.

Rosemary, zinc, egg quality, blood metabolites, laying hen