The effect of different dietary fat sources and various types of growth promoting additives on laying hens performance and egg quality traits in the late phase of production

In this study, the effect of fat source and type of growth promoting additives in laying hens diets on productive performance and egg quality traits was investigated. In a (2×3) factorial experiment,108 ninety-six week-old Hy-Line W-36 laying hens treated with 2 fat sources (vegtable fat - yellow grease and fat powder) and 3 types of growth promoting additives (none-additive,probiotic and antibiotic) for 12 weeks.The birds were allocated randomly in six treatments with six replicates (3 birds per replicat). Results showed that None of the performance variables (egg production rate, egg mass, average egg weight, feed intake and feed conversion ratio) were affected by the supplemental fat sources (P> 0.05). The addition of probiotic in feed resulted in significant reductions in feed intake, egg production and egg mass as well as in yolk percent (P