SUMMARY
The current study aimed to investigate rumen-protected L-arginine (ARG) and equine Chorionic Gonadotropin (eCG) treatments effect on ovarian activity, fertility parameters, lamb birth weight, and certain blood parameters in synchronized ewes under Upper Egypt condition. Thirty six native adult and clinically healthy ewes were divided into three equal groups (12 ewes/each), G1: (CG) control group, G2: (eCG), the animals received a vaginal sponge impregnated with 40 mg medroxy progesterone acetate (MAP) for 14 days and injected with 400 IUeCGat the day of sponges withdrawal, and G3: (ARG) ewes were treated with vaginal sponges for 14 days during the same time animals were treated orally with 20 mg/kg body rumen-protected L-Arginine. An ultrasonic device was used to monitor ovarian activity and serum samples were taken 24hrs, 48hrs, and 72hrs after therapy ended, as well as once a month for the first three months of pregnancy to determine glucose, urea, AST and ALT levels. Natural mating was used with fertile rams when estrus behavior was detected. The results demonstrated significant (P<0.05) changes in the diameter of large-follicles on the right and left ovaries after 24hrs of treatment among the treated and control groups. After 72hrs of treatments, the ARG group had a considerably higher (P<0.05) diameter of small and large follicles on the right ovary than the other groups .the diameter of large follicles and CL in the ARG group on the left ovary were significantly larger (P<0.05) than that of the other animals. However, comparing the treatment and control groups, there were significant differences (P<0.05) in estrus response, conception, lambing and fecundity rate. After the 7th and 15th days of lambing the ARG group had heavier (P<0.01) lambs than that of control group. The concentrations of the serum glucose, urea, ALT and AST were higher in the treated groups than that in the control groups. In conclusion, after progestagine synchronization therapy with eCG or rumen protected L-arginine improved reproductive indices in ewes and lamb birth weight under Upper Egypt conditions.