Abstract Background: As amajor part of the cost of broiler farms is related to their feed, breeders are looking for diets at a reasonable price. One of these affordable ingredients is sesame meal (SM), which can be used to replace soybeanmeal (SBM) in diets. Objectives: This study aims to investigate the effect of replacing SBMwith SM in diets with different levels of calcium (Ca) and phytase (Phy) during the grower (11–24 days), finisher (25–42 days) and whole phases (11–42 days) on the growth performance, carcass characteristics and blood serum parameters of broiler chickens. Methods: A total of 600 1-day-old Ross 308 broiler male chicks were randomly dispensed to 12 dietary treatments with five replicates (10 birds per replicate) based on a completely randomized design in a factorial arrangement of 3 × 2 × 2 with 3 levels of SM (0%, 10% and 20%), 2 levels of Ca (standard (0.87% and 0.79% for grower and finisher phases, respectively) and 0.2% higher than the standard amount) and 2 levels of Phy (0 and 700 FTU/kg diet). Results: During the study, the significant effects of SM, Ca and Phy on the daily average body weight gain (DAWG) and daily feed intake (DFI) were observed, whereas for the feed conversion ratio, only the effect of SM was significant (p < 0.05). During the finisher and whole phases, the SM and Ca levels influenced the DAWG and DFI, whereas the interaction between Phy and Ca was also significant forDAWG(p<0.05). The main effects of SM and Ca on the relative weights of breast, heart and liver were significant (p<0.05).Application of 20% ofSMsignificantly reduced serumCa concentration (p < 0.05). Conclusion: Generally, the inclusion of more than 10% of SM in the broilers diet is not recommended. In addition, the use of Phy and Ca levels 0.2% higher than standard in broilers diet could improve the birds’ performance.

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