Pakistan Journal of Biological Sciences1028-88801812-5735Asian Network for Scientific Information10.3923/pjbs.2006.2503.2507Shams-EsfandabadiN. ShiraziA. BonyadianM. 122006913Various hormonal treatments have been used in attempts to improve pregnancy rate. In cattle GnRH or GnRH agonists were used at first or later AI and at times ranging from 6 h before to 5, 6, 11, 14, or 15 days after AI. The objective of this study was to evaluation the effect of administration of GnRH within 3 h after estrous observation on conception rate in dairy cows. Within 3 h after standing estrous cows in treatment group (n = 42) received an i.m. injection 5 mL of GnRH (gonadorelin, Aburaihan, Iran, Each mL contains: 5 μg luliberin A). Controls cows (n = 42) did not received any treatment. The study population was stratified by parity, milk yield production, days in milk and number of AI. Pregnancy rate between GnRH treated and control cows were 28.57 and 38.09%, respectively. There was no significant differences between two groups (p<0.05).]]>Butler, W.R., J.J. Calaman and S.W. Beam,199674858865Bulter, W.R.,200060/61449457Chebel, R.C., J.E.P. Santos, J.P. Renolds, R.L. Cerri, S.O. Juchem and M. Overton,200484239255Chenault, J.R.,199073633638Coulson, A., D.E. Noakes, J. Hamer and T. Cockrill,1980107108109Day, M.L.,20032003pp: 179185De Vries, A. and C.A. Risco,20058831553165Diskin, M.G. and J.M. Sreenan,198059463468Garrett, J.E., R.D. Geisert, M.T. Zary and G.L. Morgan,198888437446Gombes, S. and W. Hansel,197337728733Henricks, D.M., J.F. Dickey and G.D. Niswender,19702346351Hermans, S.A., C.W. Young and J.W. Rust,198770712715Howard, J.M., R. Manzo, J.C. Dalton, F. Fargo and A. Ahmadzadeh,200595224233Inskeep, E.K., 20022002pp: 255-279pp: 255-279Kaim, M., A. Bloch, D. Wolfenson, R. Braw-Tal, M. Rosenberg, H. Voet and Y. Folman,20038620122021Kerbler, T.L., M.M. Buhr, L.T. Jordan, K.E. Leslie and J.S. Walton,199747703714Lamming, G.E., A.O. Darwash and H.L. Back,198937245252Lee, C.N., J.K. Kritser and R.L. Ax,19856814631470Lewis, G.S., D.W. Caldwell, C.E. Reroad, H.H. Jr. Dowlen and J.R. Owen,19907366`72Lopez-Gatius, F., P. Satolaria, A. Martino, F. Deletang and F. De Rensis,200665820830Lucy, M.C. and J.S. Stevenson,198635300311Lucy, M.C.,20018412771293Mann, G.E., G.E. Lamming, R.S. Robinsom and D.C. Wathes,199954317328Mann, G.E. and G.E. Lamming,2001121175180Mee, M.O., J.S. Stevenson, R.K. Scoby and Y. Folman,19907315001507Mee, M.O., J.S. Stevenson, B.M. Alexander and R.G. Sasser,1993in vitro production of progesterone in dairy cows.]]>71185198Nakao, T., J. Shirakawa, M. Tsurobayashi, K. Oboshi, T. Abe, Y. Sawamukai, N. Tsunoda and K. Kawata,19847489495Nebel, R.L. and S.M. Jobst, 19988111691174Perry, G.A., T.W. Geary, M.C. Lucy,2002805252Perry, G.A., M.F. Smith and M.C. Lucy,2003815252Ryan, D.P., S. Snijders, T. Condon, M. Grealy, J. Sreenan and K.J.O. Farrell,199434179191Santos, J.E.P., W.W. Thatcher, R.C. Chebel, R.L.A. Cerri and K.N. Galvao,200482-83513535Sartori, R., G.J.M. Rose and M.C. Wiltbank,20028528132822Sreenan, J.M., M.G. Diskin and D.C. Morris,20002693104Thatcher, W.W., K.L. Macmillan, P.J. Hansen and M. Drost,198931149164Twagiramungu, H., L.A. Guilbault and J.J. Dufour,19957331413151Ullah, G., J.W. Fuquay, T. Keawkhong, B.L. Clark, D.E. Pogue and E.J. Murphey,19967919501953Washburn, S.P., W.J. Silvia, C.H. Brown, B.T. McDaniel and A.J. McAllister,200285244251Wilson, S.J., R.S. Marino, J.N. Spain, D.E. Spiers, D.H. Keisler and M.C. Lucy,19988121242131Wiltbank, M.C., P.M. Fricke, S. Sangsritavong, R. Sartori and O.J. Ginther,20008329983007Wolfenson, D., W.W. Thatcher, J.D. Savio, L. Badinga and M.C. Lucy,199442633644Wolfenson, D., H. Sonego, A. Bloch and A. Shaham-Albalancy,2002228190Yaniz, J.K., K. Murugavel and F. Lopez-Gatius,2004398993