Abstract
The present study is a trial to improve the reproductive performance of dairy cows following the administration of an immunostimulant prebiotic drug during the transition period. A total number of 30 dairy cows, 3-8 years old and 1-6 parities, were assigned into two comparable groups: 20 cows were taken Celmanax, as a immune-stimulant prebiotic drug, and 10 cows were left as control. The obtained results showed a non-significant reduction in the rate of retained placenta and the number of service/conception, significant shortness in time of uterine involution and the days open as well as improvement of the conception rate for the immunized rather than for the non-immunized dairy cattle. The serum IgG and IgM increased, while the serum Nitric oxide decreased from the 30th day before to the 15th day after parturition in the immunized group. From the present study, it can be concluded that supplementation of dairy cattle by Celmanax, as an immunopotentiating factor, helps in improvement of the reproductive performance of the dairy cattle incorporation with the increase in the serum immune-stimulant responses of IgG / IgM and the decrease in the serum nitric oxide.

Key words: Reproductive performances-Dairy cows-Immunostimulant-Transition period