The Effects of Dose and Route of Administration Of
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USE OF STEROID HORMONES OR GnRH TO SYNCHRONIZE AND RESYNCHRONIZE FOLLICULAR WAVE EMERGENCE, ESTRUS, AND OVULATION IN CATTLE A Thesis Submitted to the College of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in the Department of Large Animal Clinical Sciences University of Saskatchewan Saskatoon By Marcos German Colazo ©Marcos German Colazo, April 2005. All rights reserved. PERMISSION TO USE In presenting this thesis in partial fulfillment of the requirements for a Postgraduate degree from the University of Saskatchewan, I agree that the Libraries of this University may make it freely available for inspection. I further agree that permission for copying of this thesis in any manner, in whole or in part, for scholarly purposes may be granted by the professor or professors who supervised my thesis work or, in their absence, by the Head of Department or the Dean of the College in which my thesis work was done. It is understood that any copying or publication or use of this thesis or parts therefore for financial gain shall not be allowed without my written permission. It is also understood that due recognition shall be given to me and to the University of Saskatchewan in any scholarly use which may be made of any material in my thesis. Requests for permission to copy or to make other use of material in this thesis in whole or part should be addressed to: Head, Department of Large Animal Clinical Sciences, WCVM. University of Saskatchewan Saskatoon, Saskatchewan S7N 5B4 ii ABSTRACT A series of experiments were designed to study alternative estrus synchronization and resynchronization protocols to facilitate the use of artificial insemination in cattle. Studies were conducted to study the effects of estradiol cypionate (ECP) on follicular dynamics, time of ovulation, and pregnancy rate to timed-AI (TAI) in CIDR- based protocols. Although administration of 1 mg ECP did not result in synchronous follicular wave emergence, a dose of 0.5 mg ECP synchronized LH release and ovulation. Administration of ECP 24 h after CIDR removal resulted in acceptable pregnancy rate. However, treatment with ECP at CIDR removal resulted in acceptable pregnancy rate only if follicular wave emergence was synchronized with estradiol-17β (E-17β). The efficacy of two estradiol preparations (5 mg of E-17β or estadiol valerate; EV) and reduced doses of EV on CL and ovarian follicular dynamics and superovulatory response were examined. When doses of 5 mg were compared, EV treatment resulted in a more variable interval to follicular wave emergence and a lower superovulatory response than E-17β. However, EV at a dose of 1 or 2 mg was efficacious in synchronizing follicle wave emergence in CIDR-treated cattle. Pregnancy rates were compared following TAI in cattle given a new or previously used CIDR and injections of estradiol, with or without progesterone, to synchronize follicular wave emergence. Pregnancy rate following TAI did not differ between cattle treated with a new or once-used CIDR, but pregnancy rate was lower in cattle treated iii with one or two twice-used CIDR. The addition of an injection of progesterone to the estradiol treatment at CIDR insertion did not enhance pregnancy rate The efficacy of progestins (used CIDR and MGA), and E-17β, ECP, GnRH, or progesterone treatment for resynchronization of estrus in cattle not pregnant following TAI were investigated. Progestin treatment resulted in the majority of nonpregnant heifers detected in estrus over a 4-d interval. Conception rates were higher in heifers resynchronized with a once-used CIDR than with MGA. GnRH at CIDR insertion synchronized follicular wave emergence in cows, but did not increase conception rate in heifers. E-17β at CIDR insertion (1.5 mg) and removal (0.5 mg) resulted in decreased pregnancy rate following TAI. In summary, protocols described in this thesis resulted in acceptable pregnancy rates following TAI and resynchronization of previously inseminated heifers with progestins resulted in variable estrus and pregnancy rates. iv ACKNOWLEDGEMENTS I wish to express my appreciation to my mentor Dr. Reuben J. Mapletoft, who has provided encouragement, patience, and guidance throughout my PhD program at WCVM. I sincerely thank my co-supervisor, Dr. John Kastelic for his valuable advice, technical assistance, and also for his constructive criticisms of my manuscripts. I would like to acknowledge my committee members for their time, effort, and guidance: Dr. Terry Carruthers, Dr. Roger Pierson, and Dr. Gregg Adams. I am so grateful to the University of Saskatchewan, AAFC, Brandon and Lethbridge Research Centers, and the cooperating producers for providing financial support, animals and equipment for my studies. I am especially indebted to Dr. Julie Small, Dr. Divakar Ambrose, Mr. Douglas Ward, the beef crew from AAFC, Brandon Research Centre, Mr. Randy Wilde, Mr. William Kerr and the staff from the University of Saskatchewan Goodale farm, Mr. Bernie Loman, Mr. Ken and Mrs. Sharon Piller, Mr. Morley Forsyth and family, and summer students Dr. Patrick Witthaker, Mr. Quinn Gavaga, Mr. Nathan Erickson, Ms. Mary Rutledge, and Mr. Lucas Siqueira for their assistance. I would like also thank my fellow graduate students, colleagues and friends that I had the opportunity to know in Saskatoon: Dr. Marcelo Martínez, Andres Arteaga and family, Andrzej Palasz, Derek Haley, Leonardo Brito and family, Rajesh Jaiswal, Robert McCorkell, Pritpal Malhi, Saravanan Durairaj, Christy Barlund, Tal Raz, Sameeh v Abutarbush, Marcelo Ratto and family, Dr. Manuel Chirino-Trejo and family, Dr. Jorge Chedrese and family, Mr. Murray Dyck and family, Mr. Nick Prpich and family and Dr. Mapletoft’s family for the support they have provided me over the last six years. I express my gratitude to the professors who have increased my knowledge, Dr. Albert Barth, Dr. Jaswant Singh, Dr. Norman Rawlings, Dr. Peter Flood, Dr. Robert Baker, and Dr. Cheryl Waldner for statistical advice and the staff from Department of Large Animal Clinical Sciences, especially Ms. Tracey Gilles and Mrs. Jackie Bahnmann for helping me to solve many administrative problems. Finally, I want to thank my parents Hector and Sofia, and my sisters Analia, Cecilia and their families, my family in law Hugo, Maria Susana and Elvira for the spiritual support in not only these six years but also in all my career. Finally, but certainly not the least, I want to thank my family, my wife, Maria Daniela, my daughter, Camila and my son, Juan Manuel. May God bless each of you!!!! vi DEDICATION I dedicate this thesis to my family, my wife, Maria Daniela, my daughter, Camila and my son, Juan Manuel for supporting me with their love. I also dedicate this thesis to my uncle Juan Carlos, who encouraged me to do research and passed away during my PhD program. vii TABLE OF CONTENTS PERMISSION TO USE……………………………………………………….……… ii ABSTRACT………………………………………………………………………….. iii ACKNOWLEDGEMENTS………………………………………………………….. v DEDICATION……………………………………………………………………….. vii TABLE OF CONTENTS……………………………………………………….……. viii LIST OF TABLES……………………………………………………………………. xv LIST OF FIGURES……………………………………………………………….…... xx LIST OF ABREVIATIONS…………………………………………………….……. xxv 1.0 GENERAL INTRODUCTION……………………………………………… 1 2.0 REVIEW OF LITERATURE…………………………………………….….. 3 2.1 Overview of the estrous cycle………………………………………….. 3 2.2 Endocrine regulation of antral follicles………………………………… 5 2.2.1 Growth pattern of ovarian antral follicles development……….. 5 2.2.2 Recruitment of follicular waves………………………………… 6 2.2.3 Selection of follicles for dominance……………………………. 7 2.3 Estrus synchronization………………………………………………….. 11 2.3.1 Estrus synchronization with prostaglandin……………….…….. 11 2.3.2 Estrus synchronization with progestogens……………………… 13 viii 2.4 Control of ovarian follicle dynamics during diestrus…………….…….. 15 2.4.1 Removal of the suppressive effect of the dominant follicle: Physical methods of removal…………………………………… 15 2.4.2 Gonadotrophin releasing hormone (GnRH)……………………. 16 2.4.3 Luteinizing hormone (LH)………………………………..……. 18 2.4.4 Human chorionic gonadotrophin (hCG)………………………... 19 2.4.5 Steroid hormones: Progesterone & estradiol…….…….………... 20 2.5 Control of estrous behaviour, gonadotrophin surge and ovulation………………………………………………………………… 23 2.6 Effect on corpus luteum function……………………………………….. 27 3.0 GENERAL HYPOTHESIS……………………………………………….…… 29 4.0 GENERAL OBJECTIVE……………………………………………………… 30 5.0 EFFECTS OF ESTRADIOL CYPIONATE (ECP) ON OVARIAN FOLLICULAR DYNAMICS, SYNCHRONY OF OVULATION, AND FERTILITY IN CIDR-BASED, FIXED-TIME AI PROGRAMS IN BEEF HEIFERS…………………………………………………………..……….….…31 5.1 Abstract……………………………………………………………………31 5.2 Introduction………………………………………………………………..32 5.3 Materials and Methods…………………………………………….………34 5.3.1 Experiment1.…………………………………………………..…..34 5.3.2 Experiment 2………………………………………………………35 ix 5.3.3 Experiment 3 ……………………………………………………. 36 5.3.4 Experiment 4 ……………………………………………………. 36 5.3.5 Statistical Analyses……………………………………………… 37 5.4 Results…………………………………………………………………… 38 5.4.1 Experiment 1 ……………………………………………………. 38 5.4.2 Experiment 2 ……………………………………………………. 39 5.4.3 Experiment 3 ……………………………………………………. 43 5.4.4 Experiment 4 ……………………………………………………. 45 5.5 Discussion …………………………………………………………………. 45 6.0 FERTILITY FOLLOWING TIMED AI IN CIDR-TREATED BEEF HEIFERS GIVEN GNRH OR ESTRADIOL CYPIONATE AND FED DIETS SUPPLEMENTED WITH FLAX SEED OR SUNFLOWER SEED……………………………………………..…………………………….. 50 6.1 Abstract…………………………………………………………….…… 50 6.2 Introduction…………………………………………………………….