The objective of the current study was to determine the effect of injected amino acid arginine on reproductive performance in ewes and on the levels of some hormones. Twenty-one non pregnant Awassi Turkish ewes were used. These ewes were divided into three equal groups. The first group were not treated which serve as control group (T1), and injected with 5-10 ml of normal saline in intramuscular. Ewes of second group (T2) were treated by injected with a 155µmol/kg arginine I.V. The third group (T3) was treated by injected with 155µmol/kg arginine intramuscular. All treated ewes were inseminated by rams for 7 days. Blood samples were taken from jugular vein on the 1st and 2nd days of arginine injection and then insert CIDR and on the 3rd
, and 16th
days of this treatment to measure the change in the levels of some hormones during treatment. The results showed arithmetic difference in the time of the estrus where the treatment of intramuscular arginine injection came first and it was followed by intravenous arginine injection and then the control. Arginine treated groups significantly the control group in the estrus appearance rate. The estrus appearance estrus rate in intravenous injection group, intramuscular injection group and control group were 71.43, 57.14, and 42.85% respectively, also there is significant increase in fertility rates were 71.43, 57.14 and 42.85% respectively. There was a significant increase in pregnancy rates were 71.43, 57.14 and 28.85% respectively. However, birth rates were 71.43, 57.14 and 28.57% respectively. Intravenous treatment showed the lowest than other treatments. The results of current research revealed no significant difference between groups in the level of progesterone hormone, furthermore there is no significant change in the hormone during all periods of the experiment except the 7th
period in IV arginine treated group. It was also observed a significant decrease in the estrogen concentration level in arginine intravenous (14.62 ±1.02) and intramuscular (15.00 ±1.98) injected groups in compared with control group (16.82 ±1.25) respectively during the first and 7th
periods of injection after the insert of CIDR as compared with the other periods. There were no significant differences in the level of cortisol between the treated groups and the control group, and also between all periods of the experiment. It was concluded from this study that injection of amino acid arginine improved the reproductive performance of Awassi Turkish ewes, taking into consideration the superiority of intravenous injector as compared with intramuscular injection which gave higher rates of estrus, fertilization, fertility, pregnancy and birth and gave the lowest proportion of barrenness as compared with control group. However, arginine had no significant effects on the level of estrogen, progesterone and cortisol.