The present study was conducted to investigate the effect of calf starter with treated and untreated wheat straw with different levels of protein on calf performance. 25 male and female Holstein calves were randomly assigned to each of the four treatments (n = 15) in a randomized complete block design with a 2 × 2 factorial experiment with two levels of nourishing feed protein (19.5 and 23.5%) and two types of Wheat straw(treated with alkali and untreated) was used. Treatments included: 1) starter feed with 5% wheat straw treated with sodium hydroxide (based on dietary dry matter) and protein level 19.5% (based on dry matter diet). 2) Starter feed with 5% wheat straw (based on dry matter) and protein level 19.5% (based on dry matter diet). 3) starter feed with 5% wheat straw treated with sodium hydroxide (based on dietary dry matter) and protein level 23.5% (on The basis of dry matter ration). 4) Starter feed with 5% wheat straw (based on dry matter) and protein level 23.5% (based on dry matter diet). During the experiment, the calves received milk (310 kilograms and 5 kilograms per day, respectively, per head), and received free access to fresh water and feed. Consumption dry matter, average daily gain and daily feed intake were calculated. Also, on days 35 and 70, four calves were taken per treatment using a rumen fluid esophagus tube. Apparent digestion was measured on day 70. The results of this study showed that the effect of nutrient protein level on nourishing feed intake (p 0.01), daily gain (p 0.01), weight gain (p 0.01) and final weight (P 0.01) was meaningful. The digestibility of dry matter (p = 0.04) and crude protein (p = 0.05) at 70 days of age was higher in treatments containing 23.5% crude protein, and the effect of wheat straw treatment on improving the insoluble fiber in neutral detergent (p 0.01) and insoluble fiber in acid detergent (p = 0.05). Amount of ruminal ammonia was increased at 70 days (p = 0.04), and the concentration of propionic acid was also significant (p = 0.04). Overall, the results of this study showed that increasing the level of crude protein in the diet along with the treatment of wheat straw with alkali can be one of the important factors in improving the response of infants' calves in feed forage. Key words : Infant calf, Alkali-treated wheat straw, Crude protein level