Pakistan Journal of Biological Sciences1028-88801812-5735Asian Network for Scientific Information10.3923/pjbs.2007.152.155Shams-EsfandabadiN. ShiraziA. 12007101It was hypothesized that suboptimal progesterone concentrations during the late embryo and early fetal period may act to compromise conceptus development in dairy cattle. The importance of progesterone during early pregnancy in cows is well established. Adequate secretion of progesterone is clearly the major requirement for success of early pregnancy. The aim of this study was to evaluate the efficacy of exogenous progesterone injection from day 2 to 5 following AI on conception rate in dairy cattle. At 48 h after the AI the cows were alternately assigned to treatment group (n = 40), received 4 consecutive day, from Day 2 to 5, i.m. injection of 100 mg progesterone (Vetagesterone, Aburaihan, Iran, Each mL contains: 2.5 mg progesterone) and control group (n = 68), received no treatment. The study population was stratified by parity, milk yield production, number of AI and days in milk. Pregnancy proportion in treatment and control groups were 30.88 and 35%, respectively. The results demonstrated that there was no significant differences between two groups (p<0.05).]]>Bage, R., H. Gustafsson, B. Larsson, M. Forsberg and H. Rodriguez-Martinez,20025722572269Butler, W.R.,19988125332539Cartmill, J.A., S.Z. El-Zarkouny, B.A. Hensley, G.C. Lamb and J.S. Stevenson,20018410511059Chebel, R.C., J.E.P. Santos, J.P. Renolds, R.L. Cerri, S.O. Juchem and M. Overton,200484239255Garrett, J.E., R.D. Geisert, M.T. Zary and G.L. Morgan,198888437446Geisert, R.D., J.L. Morgan, E.C. Short and M.T. Zavy,19924301305Grohn, Y.T. and P.J. Rajala-Schultz,200060-61605614Hansen, P.J. and C.F. Arechiga,1999773650Kerbler, T.L., M.M. Buhr, L.T. Jordan, K.E. Leslie and J.S. Walton,199747703714Lopez-Gatius, F., P. Santolaria, J.L. Yaniz and R.H.F. Hunter,20046215291532Lucy, M.C.,20018412771293Mann, G.E. and G.E. Lamming,199934269274Mann, G.E. and G.E. Lamming,2001121175180Mann, G.E., M.D. Fray and G.E. Lamming,2006171500503Moreira, F., C. Orlandi, C.A. Risco, R. Mattos, F. Lopes and W.W. Thatcher,20018416461659Robinson, R.S., G.E. Mann, G.E. Lamming and D.C. Wathes,19991602133Santos, J.E.P., W.W. Thatcher, R.C. Chebel, R.L.A. Cerri and K.N. Galvao,200482-83513535Santos, J.E.P, S.O. Juchem, R.L.A. Cerri, K.N. Galvao and R.C. Chebel et al.,200487868881Shelton, K., M.F.G. De Abreu, M.G. Hunter, T.J. Parkinson and G.E. Lamming,199090110Starbuck, G.R., A.O. Darwash, G.E. Mann and G.E. Lamming,20012001Starbuck, M.J., R.A. Dailey and E.K. Inskeep,2004842739Strong, A.J.H., J.M. Sreenan, M.G. Diskin, J.F. Mee, D.A. Kenny and D.G. Morris,20056412121224Villarroel, A., A. Martino, R.H. Bondurant, F. Deletang and W.M. Sischo,20046115131520Walton, J.S., G.W. Halbert, N.A. Robinson and K.E. Leslie,199054305308