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THE EFFECT OF PREOVULATORY CONCENTRATION OF ESTRADIOL AND LENGTH OF PROESTRUS ON PREGNANCY RATE TO TIMED AI AND EMBRYO TRANSFER IN BEEF CATTLE

Cruppe, Leandro Henrique
http://rave.ohiolink.edu/etdc/view?acc_num=osu1418989818

Abstract Details

2015, Doctor of Philosophy, Ohio State University, Animal Sciences.
In cattle, there are 3 time frames when early pregnancy losses may occur; before maternal recognition of pregnancy (MRP), during MRP (~d 15 to 18) and after MRP up to pregnancy diagnosis around d 30. Losses before MRP may be attributed to problems in fertilization, gamete transport and early embryonic death; mainly related to follicle/oocyte quality. Embryonic mortality during MRP may be related to insufficient production of interferon t by the developing embryo and consequent activation of PGF2a induced regression of the CL. Finally, losses occurring after MRP to the first accurate pregnancy diagnosis around d 30 may reflect the inability of the uterus to sustain the embryo. A powerful approach to begin to partition these losses would be to use AI and ET in the same experiment. In this manner, losses related to follicular/oocyte maturity and fertilization/gamete transport would be present in females that were AI but minimized in cows that received a healthy embryo via ET. Postpartum beef cows (n = 327) were used to compare the effect of preovulatory estradiol concentration (Pre-E2) and length of proestrus on pregnancy rate achieved with timed AI (AI) vs. embryo transfer (ET). Ovulation was pre-synchronized with the 5-d CO-Synch + CIDR protocol and follicle ablation was performed 6.5 d later (d -7 of experiment). Cows received 50 mg PGF2a on either d -3 (3 d proestrus; long proestrus treatment; LPE), or on d -1.5 (1.5 d proestrus; short proestrus treatment; SPE) and 100 µg GnRH on d 0. Ultrasonography was performed on d -7 and 0 to confirm ovulation to pre-synchronization and ovulatory follicle diameter, respectively. Blood samples on d -3, -1.5 and 0 were used to determine Pre-E2. Blood samples on d -3, d 0 and d 7, 10, 20, 25 and 35 were analyzed for progesterone (P4) to confirm presence of CL on d -3, its regression and formation and lifespan of the new CL, respectively. Cows in the LPE and SPE treatments were either AI on d 0 or ET on d 7, resulting in 4 distinct combinations (LPE-AI, n=77; LPE-ET, n=67; SPE-AI, n=98; SPE-ET, n=85) in a 2 x 2 factorial arrangement. Pregnancy diagnosis was performed on d 35. Ovulatory follicle diameter (11.9 ± 0.1 mm) and P4 on d -3, 0, 7 and 10 did not differ among treatments. As expected, Pre-E2 on d -3 (4.5 ± 0.1 pg/ml) was similar between treatments and greater (P < 0.05) in the LPE on d -1.5 and 0 (7.6 ± 0.2; 10.1 ± 0.3 pg/ml, respectively) compared to SPE (5.1 ± 0.2; 9.2 ± 0.2 pg/ml, respectively). Pregnancy rate was greater (P < 0.05) in the LPE treatment and AI group (LPE-AI, 69.9%; LPE-ET, 55.7%; SPE-AI, 51.2%; SPE-ET, 43.7%) compared to the SPE treatment and ET group, however no interaction of treatment x breeding technique was detected for pregnancy rate. Reduced Pre-E2 was a primary outcome of shortened proestrus which resulted in similar reductions in AI (26.8%) and ET (21.5%) pregnancy rate; relative to that achieved in the LPE treatment. Based upon the similarity of these responses, it is concluded that the primary impact of shortened proestrus and deficient Pre-E2 is to impair the ability of the uterus to sustain the embryo during early gestation.
Michael Day (Advisor)
Steven Loerch (Committee Member)
Gustavo Schuenemann (Committee Member)
Thomas Geary (Committee Member)
Kichoon Lee (Committee Member)
154 p.
Animal Sciences; Veterinary Services
Preovulatory Estradiol, AI, ET

Recommended Citations

Citations

  • Cruppe, L. H. (2015). THE EFFECT OF PREOVULATORY CONCENTRATION OF ESTRADIOL AND LENGTH OF PROESTRUS ON PREGNANCY RATE TO TIMED AI AND EMBRYO TRANSFER IN BEEF CATTLE [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1418989818

    APA Style (7th edition)

  • Cruppe, Leandro. THE EFFECT OF PREOVULATORY CONCENTRATION OF ESTRADIOL AND LENGTH OF PROESTRUS ON PREGNANCY RATE TO TIMED AI AND EMBRYO TRANSFER IN BEEF CATTLE. 2015. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1418989818.

    MLA Style (8th edition)

  • Cruppe, Leandro. "THE EFFECT OF PREOVULATORY CONCENTRATION OF ESTRADIOL AND LENGTH OF PROESTRUS ON PREGNANCY RATE TO TIMED AI AND EMBRYO TRANSFER IN BEEF CATTLE." Doctoral dissertation, Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1418989818

    Chicago Manual of Style (17th edition)

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