This experiment was conducted to determine the effects of calcium salts of fatty acids on laying hens performance. The MEn values of fatty acids and calcium salts of fatty acids estimated by biological assay and the regression equations of MEn values of fatty acids and calcium salts on rate of inclusion of fatty acids or calcium soaps in diet were calculated.The MEn of the fatty acids and calcium salts were, 6588 (Kcal/g) and 5760 (KcaI/Kg) respectively. 189 White Leghorn (Hy-Line) layers. 52-wk-old. having similar body weight and egg production. were divided into seven groups with three replicates, fed six diets with different fat source (fatty acids or calcium soaps) and rate of inclusion (1.5%, 3%, 4.5%) or control diet (had nO supplement of fatty acids or calcium soaps). The period of experiment was 12 wk. A randomized complete design with 7 diets, 3 replicate with 9 hens in each replicate was employed to analyse the data. During the length of experiment. 8 variables including: egg weight. Haugh unit, shell weight. percent of shell, egg production, feed consumption. egg mass, were measured and feed conversion ratio were calculated.The obtained results show that: weight, Haugh unit, shell weight and percent of shell of egg were not significantly affected by dietary treatments, but egg production. feed consumption, egg mass and feed conversion ratio were affected (p
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