Mike Smith presentation ct., 1 PHYSILGICAL PRINCIPLES UNDERLYING SYNCHRNIZATIN F ESTRUS M.F. Smith, G.A. Perry, J.A. Atkins, K.G. Pohler, R.M. Wallace, S.E. Dickinson, A.. Gatea and D.J. Patterson Division of Animal Sciences, University of Missouri, Columbia Department of Animal and Range Sciences, South Dakota State University verview Physiology of the bovine estrous cycle synchronization products Hormonal management of the luteal phase Hormonal management of follicular waves Physiological factors affecting pregnancy rate to FTAI Characteristics of the Estrous Cycle Length of the estrous cycle Average 1 days (range 17 to days) Two follicular waves 17 to days Three follicular waves 1 to days " (standing heat) 1 to 1 hours (range to 3 hours) Approximately 3 hours after the beginning of standing estrus Percentage of cows 3 Duration of -5-11-15 1-1-5 >5 Duration of, h White et. al., Influence of confinement area on the number of mounts per estrus (P >.5) Influence of the number of cows in estrus on number of times cows are mounted in drylot or pasture Mounts 35 3 5 15 5 3. Drylot 7.9 Pasture Number of mounts Pasture Drylot 5. c 5 7.7 a,b 3.9 b 3 11. a 1-3 - 7 + Number of Cows in a,b superscripts differ P <.7 b,c superscripts differ P <. ARSBC1 1
Mike Smith presentation ct., 1 varian Structures Graffian follicle Corpus luteum Dominance Hormone concentration The Estrous Cycle Atresia Selection Recruitment CL Progesterone 5 15 Stages of the Estrous Cycle Follicular and Phases Follicular Phase Growth Dominance Estrogen Selection LH Surge Luteal Phase Maturation of the preovulatory follicle Estrous behavior (induced by the LH surge) Luteal Phase Corpus Luteum and Pregnancy Growth Regression Growth Maintenance P PGF Embryo PGF 1 1 1 1 P = Progesterone CIDR and MGA PGF = Prostaglandin F Lutalyse, ProstaMate, In Synch, Estrumate, estroplan 1 1 1 1 Day of the Estrous Cycle Maternal recognition of pregnancy day 15 to 1 Caution PGF can induce abortion in pregnant cows ARSBC1
Mike Smith presentation ct., 1 Physiology of Follicular Waves Problem of Anestrus! Dominance FSH FSH Selection Recruitment 1 1 1 1 Day of the Estrous Cycle Progesterone (ng/ml) 5 3 1 15 31 Day Problem of Anestrus! FTAI Pregnancy rate in Anestrous Cows Progesterone (ng/ml) GnRH 5 r 3 CIDR 1 15 31 31 Cows Studies " Bader et al., 5 " Schafer et al., 7 " Busch et al., " Wilson et al., Estrous Cycling - " 139/31 = 57% Anestrus " 1/31 = 3% 9 7 5 3. 3. Day Estrous Cycling Anestrus Hormones utilized in Synchronization Protocols Progesterone/Progestins Prostaglandin F α GnRH Progesterone Biological Functions Inhibit estrus/ovulation Preparation for pregnancy Maintenance of pregnancy ARSBC1 3
Mike Smith presentation ct., 1 Progestins/Progesterone Role in Synchronization Inhibit estrus/ovulation Prostaglandin F α Biological Function Luteal regression in nonpregnant animals Induce cyclicity Role in Synchronization Induce premature luteal regression Gonadotropin Releasing Hormone (GnRH) Biological Function Control secretion of LH Hormonal management of the luteal phase Progestins Induces gonadotropin surge Role in Synchronization Induce ovulation Prostaglandin F α Synchronize follicular waves Progestins Melengestrol Acetate - MGA Controlled Internal Drug Release - CIDR ARSBC1
Mike Smith presentation ct., 1 C Inhibition of Following Long-term Progestin Treatment Progestin Treatment MGA for 1 days 1 1 1 1 Progesterone Pregn--ene-3, -dione MGA (melengestrol acetate) -methyl-17-alpha-acetoxy-1-methylene-pregn-, -diene-3, -dione C CH CH3 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 CL Regressed 1 (less fertile) Follicle Diameter (mm) 1 1 Persistent Follicles Persistent Follicle (PF) vs. Growing Follicle (GF) PF GF -1 - - - - - Prostaglandin F α (PGF) (Lutalyse, ProstaMate, Estrumate, In Synch, estroplan) Causes CL regression No effect on noncycling cattle No induction of cyclicity No Jump-start Days Relative to (day ) Effective days to 1 of the estrous cycle (day = estrus) PGF a Effect of stage of the cycle Hormonal management of follicular waves: GnRH (Cystorelin, Factrel, Fertagyl, vacyst) Induces ovulation N N YES 1 1 1 1 Synchronizes follicular waves Induces formation of a CL Day of the Estrous Cycle ARSBC1 5
Mike Smith presentation ct., 1 GnRH-Induced During a Follicular Wave YES N Endocrinology of Fertility in Cattle YES N 3 1 1 1 1 1 Day of the Estrous Cycle Factors Affecting Pregnancy Rate Progesterone at PGF to GnRH-1 Pregnancy Rate Follicle Size at AI Estradiol at AI Progesterone after AI Atkins et al 13 How do you determine what went wrong? Calculate the conception rate and/or pregnancy rate Is it actually low? Ask for help Veterinarian, AI rep, extension specialist, etc. Don t make any assumptions. When trouble shooting try to systematically work through the possibilities. ARSBC1
Mike Smith presentation ct., 1 What are the primary problems? Cattle are not good candidates for an estrus synch/ai program Protocol compliance Sire selection Facilities Shipping (trucking) stress Cattle lose weight during the breeding season. Failure to pay attention to detail. Unlikely the biological activity of the ES products is compromised Management considerations for selecting heifers and cows for synchronization of estrus Before you start an estrous synch and AI program Heifers What has the pregnancy rate of your heifers been over the past few years? Have your heifers received growth promoting implants? Have you selected an appropriate target weight? Heifers-contd. Have your heifers attained 5% of their mature body weight? What proportion of your heifers have a reproductive tract score of? Before you start an estrous synch and AI program Postpartum Cows What has the pregnancy rate in your cows been over the past few years? Postpartum Cows contd. What proportion of your cows are cycling by the start of the breeding season? What is the current length of your breeding season? What was the body condition score of your cows at calving? ARSBC1 7
Mike Smith presentation ct., 1 Postpartum Cows contd. Postpartum Cows and Heifers What is the current body condition score of your cows? How many days postpartum will your cows be when estrus synchronization is initiated? How much time can you devote to estrus detection? Considering your handling facilities, how many cows can you breed in an hour? Synchronization Products Progestins Melengestrol Acetate EAZI-BREED CIDR Prostaglandin F α Lutalyse ProstaMate In Synch Estrumate estroplan Synchronization Products GnRH Cystorelin Fertagyl Factryl vacyst Hormonal management of follicular waves GnRH Induces dominant follicle to ovulate Estradiol dominant follicle turnover ( FSH) Progesterone dominant follicle turnover ( LH) GnRH (Cystorelin, Factrel, Fertagyl, vacyst) Induces ovulation Synchronizes follicular waves Induces formation of a CL ARSBC1
Mike Smith presentation ct., 1 Percentage of Cows 1 1 1 1 Variation in Time 3 3 3 3 3 Time of (h) White et. al., Role of Progestins in Synchronization Synchronization of estrus in beef heifers & cows dairy heifers & cows Advances onset of puberty in heifers Advances return to estrus after calving in cows GnRH Induced Surge of LH GnRH Injection LH Surge to Hours after GnRH injection to 3 ARSBC1 9