Effects of Rosemary Essential Oil and Zinc on Performance, Egg Quality Traits, and Some Serum Metabolites in Laying Hens

This study was conducted to evaluate the effects of dietary supplementation of rosemary essential oil (reo) and zinc (as zinc sulfate) on performance, egg quality traits, and some serum metabolites in laying hens. lohmann lsl-lite laying hens (44-weeks-old) were randomly allocated into four treatments, each comprising of six replicates of six birds. one group served as the control and was fed a corn-soybean meal based diet without reo or zinc supplement. the other groups received the control diet supplemented with 200 mg/kg reo, 40 mg/kg zinc, or both reo and zinc, respectively. 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 with reo. birds fed reo had lower (p < 0.05) serum total cholesterol level compared with the control. however, this effect was not observed by feeding both zinc and reo. these results indicated that the dietary inclusion of reo had a potential to improve the egg quality traits and serum cholesterol level in laying hens.