The current study aimed at evaluation the effects of in ovo injection of the myostatin inhibitor, myostatin
pro-peptide (MyoPro) gene on growth performance of Fayoumi chicken. A total number of 200 Fayoumi
fertilized pure breed eggs were obtained from EL-Tkamoly poultry project - EL-Azab – Fayoum. Eggs were
divided into two equal groups. Group 1(control group, n=100) was injected with saline, and group 2 (treated
group, n=100) injected with Myo-pro gene. Growth parameters were recorded (body weight, body weight
gain, feed consumption per group was measured for calculating feed conversion ratio). The obtained results
revealed that injection of myo-pro to Fayoumi eggs resulted in highly significant increase in body weight and
weight gain during all experimental period when compared with control group. Feed conversion ratio of
Myo-pro injected group was significantly lower than control group. However, food intake showed no
significant change between the two groups. From the obtained results, injection of Myo-Pro gene causing
marked increase in body weight gain and improvement in feed conversion ratio without change in food
intake in fayoumi chicken.