Background: Seaweeds are rich in complex carbohydrates, proteins and low molecular weight nitrogenous compounds, lipids, organic minerals, vitamins and pigments. The aim of the study was to evaluate the effect of seaweed formulations on nutrient utilization, growth performance, serum antioxidant activity and cell mediated immune response of crossbred calves. Methods: Eighteen male crossbred calves (130±7.56 kg body weight) were divided into 3 groups of 6 each based on complete randomized design. Concentrate mixture was formulated with crushed maize, de-oiled soybean meal, wheat bran, mineral mixture and common salt for feeding of calves in control (T0) group, while treatment groups T1 and T2 were supplemented with AF-KWP or AFRD-5 at the rate of 4% of concentrate mixture with 1% calcium carbonate and 1% dicalcium phosphate replacing mineral mixture and common salt offered in T0. Experiment was conducted for a period of 240 days. Blood was collected from each calve at 0, 100 and 200 days of experiment. At the end of the experimental feeding a metabolism trial was conducted and cell mediated immune response was asassed. Result: There was no significant difference between groups regarding nutrient utilization, total dry matter intake, gain in body weight and feed conversion ratio. However, significant (P less than 0.001) differences were observed in serum antioxidants status. Moreover, the mean values for skin thickness differed significantly (P less than 0.001) among different groups and values were 14.03, 15.54 and 16.62 in T0, T1 and T2 group, respectively. Hence seaweed formulations might improve antioxidant status and cell mediated immune response without affecting the nutrient utilization and growth performance of crossbred calves.