This study aimed to evaluate the influence of choline chloride supplementation on the growth performance of feedlot calves. Thirty-two crossbred calves with a mean initial body weight of 305.71±4.09 Kg were divided into three groups of 10, 11 and 11 animals, randomly. The animals were distributed to one of three dietary treatments, control, choline15 and choline 30 (the rations supplemented with 0, 15 and 30 g choline chloride, respectively). The animals were fed on concentrate feed at a rate of about 2.15% of their live body weight and rice straw open access. Supplementing animal ration with choline chloride did not significantly affect all nutrients' digestibility and feeding value. The animals supplemented with 30 g choline chloride recorded significantly higher (P=0.037) total serum protein concentration compared to the other groups. The group received a ration supplemented with 30 g of choline chloride and recorded significantly higher final weight, total gain, and mean daily gain. Data showed significant improvement in TDN, CP and DCP conversion for the animal received ration supplemented with 30 g choline chloride compared to the control group. In conclusion, supplementing fattening calves' ration with rumen-protected choline could improve average daily gain and feed conversion.