El-Zarkouny, S. Z.Cartmill, J. A.Stevenson, Jeffrey S.2011-08-022011-08-022011-08-02http://hdl.handle.net/2097/11942Administering progesterone to lactating dairy cows has sometimes proven effective in increasing pregnancy rates. In this study, cows were treated with the Ovsynch protocol in addition to supplemental progesterone given for 7 days between the first gonadotropin- releasing hormone (GnRH) injection and the prostaglandin F2á (PGF2á) injection. Conception rates were greater in lactating Holstein dairy cows receiving exogenous progesterone (62.5%) than in controls treated with only the Ovsynch protocol (35.5%). In addition, progesterone supplementation increased embryo survival between 28 and 56 days of pregnancy.DairyOvsynch protocolProgesteroneLactating cowsPregnancy ratesConference paper