N. Zahroojian - Department of animal science, Faculty of Agriculture and Natural Resources, University of Tehran, P. O. Box: ۳۱۵۸۷-۷۷۸۷۱, Karaj, Islamic Republic of Iran.
H. Moravej - Department of animal science, Faculty of Agriculture and Natural Resources, University of Tehran, P. O. Box: ۳۱۵۸۷-۷۷۸۷۱, Karaj, Islamic Republic of Iran.
M. Shivazad - Department of animal science, Faculty of Agriculture and Natural Resources, University of Tehran, P. O. Box: ۳۱۵۸۷-۷۷۸۷۱, Karaj, Islamic Republic of Iran.

In this experiment, a total of ۱۲۸ Hy-line W۳۶ hens at ۶۳ weeks of age were used. The hens were put at random into ۴ treatment groups (۴ replicates and ۳۲ hens per treatment) and were fed four different diets: three diets with different levels of Spirulina (۱.۵, ۲.۰ and ۲.۵%) and one control group based on wheat and soybean meal. All birds were housed in commercial cages, had ad libitum access to water, and were fed ۱۰۰ g bird-۱ per day. Egg production, feed intake, feed conversion ratio, egg weight, yolk index, Haugh unit, shell thickness, shell weight, specific gravity, egg yolk cholesterol, and yolk color were compared with the control group. Egg yolk color was measured by the BASF Ovo-color fan. Our results indicated that these traits did not show any significant changes with the Spirulina addition (P> ۰.۰۵), while a significant increase in egg yolk color was observed in the treatments that received the Spirulina (P< ۰.۰۰۰۱). Yolk color scores of the control group and different levels of Spirulina (۱.۵, ۲.۰ and ۲.۵%) were ۱.۵, ۱۰.۵, ۱۱.۴ and ۱۱.۶ in BASF color fan, respectively. There were not significant differences between the treatments with ۲.۰ and ۲.۵% of Spirulina. In conclusion, this study can suggest use of ۲.۰~۲.۵% of Spirulina in diet to produce an aesthetically pleasing yolk color.

Natural pigment, Marine algae (Spirulina platensis), Yolk cholesterol, Yolk color