This experiment was conducted at Poultry field, Agricultural Research and Experiment Station, College of Agriculture, Al-Muthanna University from 12/2/2020 to 6/1/2020. A total of 240 oneday, 40 g, Ross 308 broiler chicks, were used. The chicks were reared in four-storey batteries. Each floor contains a cage of dimensions 1.5 × 1 m. The chicks were randomly distributed to four experimental treatments of 60 chicks. For each treatment, three replicates of the treatment (20 chicks/duplicate). The treatments were as T1, T2, T3 and T4were add water extract of chia seeds to drinking water by 0, 2, 4 and 6 ml/liter of drinking water respectively.