Browsing by Subject "CIDR"
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Item Effects of GnRH and prostaglandin combined with a short progestin regimen on the synchrony of estrus and ovulation in ewes during the breeding season(2012-08-10) Calhoun, Andy Kyle; Calhoun, Andy Kyle; Dickison, Will J.; Salisbury, Micheal; Scott, Cody; Keith, Susan; Angelo State University. Department of Agriculture.The lack of effective, consistent synchronization protocols for ewes is a barrier to the use of artificial insemination in sheep. This study compared the estrus and ovulation percentage and window of synchrony of estrus and ovulation for ewes synchronized with three experimental protocols. The industry’s current standard protocol using PG600, an 11 d CIDR and PGF2a was compared to two alternative protocols utilizing GnRH, a 7 d CIDR and PGF2a. Forty Suffolk ewes were divided into 5 groups and each group was placed on a different protocol. Blood sampling began 18 h following CIDR removal and samples were collected every 2 h for 19 consecutively collections. Mean serum concentrations of LH differed between groups (P<0.05) from 22-42 h following CIDR removal. The two protocols using the shorter 7 d progestin regimen and GnRH to control follicular dynamics resulted in higher estrus and ovulation rates and an acceptable window of synchrony.Item Evaluation of the effect of progesterone CIDR Devices on circulating levels of progesterone in cyclic ewes(Texas A&M University, 2005-02-17) Satterfield, Michael CareyA homogeneous group of thirty-one crossbred ewes was used to determine the effect of administering a progesterone Controlled Intravaginal Drug Releasing Device (CIDR) on circulating levels of progesterone in the subsequent cycle following CIDR removal. Circulating progesterone levels were determined for each ewe through daily blood collection via jugular venipuncture. Each ewe underwent a pretreatment 25 day sampling period (Period 1), a 12 day treatment period characterized by the presence of the CIDR (Period 2), and another 25 day sampling period following CIDR removal (Period 3). During the initial period of the study, progesterone levels in peripheral circulation changed (P < 0.0001, effect of day) in accordance with stage of the estrous cycle and were elevated during the luteal phase. In the second period of the study, progesterone levels were elevated (P < 0.0001) in ewes due to exogenous progesterone from the CIDR device (Period 1 versus Period 2: 1.3 ? 0.1 ng/ml versus 2.4 ? 0.1 ng/ml, respectively). After withdrawal of the CIDR in the third period of the study, circulating progesterone levels were not (P > 0.10) different from those observed in the initial period of the study (Period 1 versus Period 3: 1.3 ? 0.1 ng/ml versus 1.4 ? 0.1 ng/ml, respectively). Data collected in this study revealed that treatment with exogenous progesterone via CIDR for a 12- day treatment period does not influence circulating levels of progesterone in subsequent estrous cycles.Item Pre- and post-synchronization methodologies to enhance the efficiency of fixed timed artificial insemination in pharmacologically-controlled breeding systems with Bos indicus-influenced cattle(Texas A&M University, 2007-04-25) Zuluaga Velez, Juan FedericoObjectives were to: 1) Evaluate the effectiveness of presynchronization with GnRH before the CO??????Synch + CIDR protocol with timed AI (TAI) at 66 h in Bos indicus??????influenced cattle; 2) Characterize ovarian events associated with the presynchronization; 3) Evaluate the efficacy of measuring vaginal electrical resistance (VER) to assess follicular maturity at TAI; and 4) Compare serum concentrations of progesterone (P4) in ovariectomized cows bearing new or previously used CIDR devices with or without autoclaving. In Exp. 1 and 2, cattle received either GnRH or saline on day ??????7. The CO??????Synch + CIDR protocol included a CIDR insert and GnRH (GnRH??????1; day 0), removal of CIDR and PGF2???? on day 7, and GnRH (GnRH??????2) and TAI 66 h after CIDR removal. In Exp. 1, pregnancy rate of females with BCS ?????? 5 tended to differ (P=0.085) between Presynch (38%) and CO??????Synch + CIDR (54%). In Exp. 2, ovulatory response to GnRH??????1 was greater (P<0.01) in the Presynchronization (58%) than in the CO??????Synch + CIDR (27.1%) group. Emergence of a follicular wave after GnRH??????1 and ovulation rate after GnRH??????2 did not differ between groups. More (P<0.01) females that developed a follicular wave after GnRH??????1 ovulated (82%) after GnRH??????2, compared to those that did not (29%). Mean VER (ohms) was greatest (101.4????0.8) on day 0 and declined (P<0.01) to 95.2????0.8 and 82????0.8, respectively, on days 7 and 10. We observed a low negative but significant relationship (r=0.38; P<0.001) between VER and follicular size on day 0, 7, and 10. VER difference (day 10 minus day 7) did not differ between females with small and large follicles at TAI. Mean concentrations of P4 during the 7??????day insertion period were greater (P<0.03) for new (3.7 ng/ml) and re??????used autoclaved (3.4 ng/ml) than for re??????used disinfected CIDRs (2.8 ng/ml). In summary, Presynch improved ovulation rate after GnRH??????1, but did not improve pregnancy rates compared to CO??????Synch + CIDR. Follicular maturity estimation was not feasible using VER as applied in this study. Autoclaving may be the best option when re??????using CIDR inserts because it creates greater concentrations of P4 during the first 48 h.