Pakistan Journal of Biological Sciences1028-88801812-5735Asian Network for Scientific Information10.3923/pjbs.2007.3557.3563KarimiA. KaramiH. MoiniM. M.SefatA.A. AhmadiHaghvirdiluE. 1220071020In order to determine different protocols of synchronization and their efficiency on pregnancy rate after fixed-timed AI (TAI), 120 dairy Holstein cows (n = 120) were assigned randomly to six groups: 1) two injections of Prostaglandin F2α (PGf2α) with 12 days apart as a control group, 2) two injections of Gonadotropin Releasing hormone (GnRH) with 9 days apart and an injection of PGf2α at day 7, 3) injection of GnRH and PGf2α with 7 days apart, then single injection of Estradiol Benzoate (EB) after 48 h, 4) injection of progesterone (P4) in conjugation with EB then after 7 days PGf2α injection and after 48 h an injection of GnRH were done, 5) as group 4 but EB was used instead of GnRH, 6)injections of PGf2α and EB conjugated with Human Chronic Gonadotrophin (hCG) with 12 h apart. Animals in group 1 (control), groups 2-5 and group 6 were inseminated after 72, 20 and 36 h, respectively. Serum P4 concentration of group 4 (4.43± 1.50 ng mL-1) was higher than control group (2.34±1.36 ng mL-1) at day 5 after insemination (p<0.05); P4 concentrations of groups 3 and 4 have significant differences with control group (2.69±2.64 and 2.56±1.40 versus 0.81±0.41 ng mL-1, respectively, p<0.05) at a day after second injection and groups 4 and 5 were in higher level of P4 concentration than control group at insemination time (3.14±1.9 and 2.89±1.8 versus 0.45±0.19 ng mL-1 respectively, p<0.05). Pregnancy rate were 0, 50, 45, 10, 30 and 45% for group 1 (control) through 6, respectively.]]>Ahuja, C., F. Montiel, R. Canseco, E. Silva and G. Mapes,20052α treatment of low body condition, anestrous Bos taurus by Bos indicus crossbred cows during the summer months in a tropical environment.]]>87203213Arechiga, C.F., C.R. Staples, L.R. McDowell and P.J. Hansen,199881390402Bartolome, J., L. Archbald, P. Morresey, J. Hernandez and T. Tran et al.,200053815825Britt, J.S. and J. Gaska,1998212210212Burke, J.M., R.L. De la Sota, C.A. Risco, C.R. Staples, E.J.P. Schmitt and W.W. Thatcher,19967913851393Burke, C.R., M.P. Boland, K.L. Macmillan,1997552333Calder, M.D., B.E. Salfen, B. Bao, R.S. Youngquist and H.A. Garverick,19997730373042Cavalieri, J., A.R. Rabiee, G. Hepworth and K.L. Macmillan,2005903955De la Sota, R.L., J.M. Burke, C.A. Risco, F. Moreira, M.A. DeLorenzo and W.W. Thatcher,199849761770Duncan, D.B.,195511142Fricke, P.M. and M.C. Wiltbank,19995211331143Ferguson, J.D. and D.T. Galligan,199315646655Folman, Y., M. Kaim, Z. Herz and M. Rosenberg,19907328172825Garverick, H.A.,1997809951004Gilbert, R.O.,1997821114Hobson, W.C. and W. Hansel,197291185190Khanum, S.A., M. Hussain and R. Kausar,2006Capra hircus) using estrumate under different management conditions.]]>9297106Kim, I.H., G.H. Suh and D.S. Son,200360809817Kristula, M., R. Bartholomew, D. Galligan and C. Uhlinger,19922a synchronization program in lactating dairy cattle.]]>7527132718Lauderdale, J.W., B.E. Seguin, J.N. Stellflug, J.R. Chenault, W.W. Thatcher, C.K. Vincent and A.F. Loyancano,1974f2α injection.]]>38964967Le Blanc, S.J., K.E. Leslie, H.J. Ceelen, D.F. Kelton and G.P. Keefe,19982α.]]>81375381Lopez-Gatius, F.,200054551558Macmillan, K.L. and A.J. Peterson,199333125Martinez, M.F., J.P. Kastelic, G.P. Adams, B. Cook, W.O. Olson and R.J. Mapletoft,20025710491059Mialot, J.P., F. Constant, P. Dezaux, B. Grimard, F. Deletang and A.A. Ponter,200360319330Michael, J., R. James, E. Kinder, K. Fike, F. Kojima, D. Colin, R. Ogle and C.R. Bunt,200050277320Momcilovic, D., L.F. Archibald, A. Walters, T. Tran, D. Kelbert, C. Risco and W.W. Thatcher,19982α (PGf2α) for synchronization of estrus and ovulation.]]>5011311139Osawa, T., T. Nakao and M. Kimura,199544835847Padula, A.M. and K.L. MacMillan,2002702336Patterson, D.J., S.L. Wood, F.N. Kojima and M.F. Smith,20002000pp: 97-110pp: 97-110Peter, A.T.,19981998pp: 349-354pp: 349-354Peters, A.R.,200588155167Pursley, J.R., M.O. Mee and M.C. Wiltbank,19952α and GnRH.]]>44915923Pursley, J.R., M.R. Kosorok and M.C. Wiltbank,199780301306Pursley, J.R., M.C. Wiltbank, J.S. Stevenson, J.S. Ottobre, H.A. Garverick and L.L. Anderson,199780295300Ryan, D.P., S. Snijders, A. Aarts and K.J. O`Farrell,199543310310Rayon, A.A., G. Evargas, C.A.Valdez and D.B. Marcial Jr.,1998363539Ryan, D.P., J.A. Galvin and K.J. O'Farrell,199956153168Schmitt, E.J.P., M. Drost, T. Diaz, C. Roomes and W.W. Thatcher,199674154160Schmitt, E.J.P., T. Diaz, M. Drost and W.W. Thatcher,19967410841091Stevenson, J.S., M.K. Schmidtand E.P. Call,198467140145Steveson, J.J., Y. Konayashi, M.P. Shipka and K.C. Rauchhotz,19962α.]]>79402410Stevenson, J.S., Y. Kobayashi and K.E. Thompson,19992α.]]>82506515Taverne, M.A.M.,199228433-440Tebble, J.E., M.J. O`Donnell and H. Dobson,2001148411413Thatcher, W.W., M. Drost, J.D. Savio, K.L. Macmillan and K.W. Entwistle et al.,1993332749Thatcher, W.W., F. Moreina, S.M. Pancarci, J.A. Bartolome and J.E.P. Santos,200223243254Todoroki, J., H. Yamakuchi, K. Mizoshita, N. Kubota and N. Tabara et al.,20015519191932Trigg, T.,200588141153Trimberger, G.W.,1948153325Twagiramungu, H., L.A. Guilbault and J.J. Dufour,19957331413151Webb, R., B.K. Campbell, H.A. Garverick, J.G. Gong, C.G. Gutierrez, and D.G. Armstrong,1999543348Xu, Z.Z., L.J. Burton and K.L. Macmillan,1995f2α and progesterone.]]>47687701