
%0 Journal Article
%A Aoyagi, Y. 
%A Ideta, A. 
%A Matsui, M. 
%A Hayama, K. 
%A Urakawa, M. 
%A Miyamoto, A. 
%A Miyake, Y. 
%T 206 EFFECTS OF A COMBINATION OF A PRID, PGF<sub>2&#945;</sub> AND eCG, ON ESTRUS SYNCHRONIZATION AND PREGNANCY RATE FOLLOWING EMBRYO TRANSFER IN HOLSTEIN HEIFERS
%J Reproduction, Fertility and Development
%D 2006/12/12
%V 19
%N 1
%P 220-220
%K 
%R https://doi.org/10.1071/RDV19N1AB206
%U https://www.publish.csiro.au/paper/RDV19N1AB206 
%X Successful bovine embryo transfer requires synchronization of luteolysis, estrus and ovulation. The objective of the present study was to evaluate the effect of a combination of a PRID, PGF2± and eCG, on estrus synchronization and pregnancy rate in recipient heifers. A PRID® (ASKA Pharmaceutical Co., Ltd., Tokyo, Japan) was inserted into the vagina at random days of the estrous cycle for 7 (n = 35) or 9 (n = 43) days. Two days before removal of the PRID, the heifers were injected with PGF2± IM (2 mL Resipron®-C containing 0.25 mg mL-1 cloprostenol; ASKA). About half of the heifers in each group received 250 IU eCG IM (Serotropin®; ASKA) at the time of PRID removal. Blood was collected several times from the start of treatment for 7 (n = 9) or 9 (n = 9) days and on the day of embryo transfer by jugular venipuncture; plasma was immediately separated and stored at -20°C until assayed for plasma concentrations of estradiol-17&#945; (E2) and progesterone (P4). The E2 and P4 determinations were performed by enzyme immunoassay after extraction by diethyl ether. Pregnancy was determined by ultrasonography on Day 30 (Day 0 = estrus). The rates of successful standing estrus (no. in estrus/PRID inserted), embryo transfer (no. transferred/estrus), and pregnancy (no. pregnancy/transferred) were compared between groups. Data were analyzed by chi-square analysis or Fisher&apos;s PLSD test following ANOVA. Injection of eCG at the time of PRID removal had no significant effect on the rates of successful standing estrus, embryo transfer, or pregnancy (P > 0.05). The proportion of heifers treated for 9 days that exhibited standing estrus (93&percnt;, 40/43) was significantly higher than the proportion of heifers treated for 7 days that exhibited standing estrus (66&percnt;, 23/35, P < 0.01). Of the heifers that were treated for 9 days, the proportion of heifers exhibiting standing estrus within 2 days after the end of treatment was significantly higher (93&percnt;, 37/40) than for heifers that were treated for 7 days (65&percnt;, 15/23; P < 0.01). Pregnancy rates of heifers treated for 9 days (84&percnt;, 32/38) and 7 days (81&percnt;, 17/21) were not significantly different. The E2 : P4 ratio normally increases during follicle growth and CL regression. The plasma E2 : P4 ratio between the time of injection of PGF2&alpha; and the time of PRID removal was significantly higher for heifers that were treated for 9 days than it was for heifers that were treated for 7 days (P < 0.01). These results suggest that a combination of PRID treatment for 9 days and injection of PGF2&alpha; 2 days before PRID removal successfully synchronized estrus in recipient heifers and led to high pregnancy rates following embryo transfer. 
