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Drews B, Rudolf Vegas A, van der Weijden VA, Milojevic V, Hankele AK, Schuler G, Ulbrich SE. Do ovarian steroid hormones control the resumption of embryonic growth following the period of diapause in roe deer (Capreolus capreolus)? Reprod Biol 2019; 19:149-157. [PMID: 31147267 DOI: 10.1016/j.repbio.2019.04.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Revised: 04/05/2019] [Accepted: 04/27/2019] [Indexed: 01/01/2023]
Abstract
Embryonic diapause in the European roe deer includes a period of five months from August to December in which embryonic development is extremely decelerated. Following exit from diapause, the embryo rapidly elongates and subsequently implants. In diapausing carnivores and marsupials, resumption of embryonic growth is regulated by ovarian steroid hormones. In the roe deer, the role of steroid hormones is not known to date. In the present study, progesterone (P4), estradiol-17β (E2) and total estrogens (Etot) were determined in blood plasma and endometrium of roe deer shot in the course of regular huntings between September and December. Steroid hormone concentrations were correlated to the corresponding size of the embryo derived from ex vivo uterine flushing and to the date of sampling. The mean plasma concentrations of P4 (5.4 ± 0.2 ng/ml, mean ± SE, N = 87), E2 (24.3 ± 2.6 pg/ml, N = 86) and Etot (21.7 ± 2.6 pg/ml, N = 78) remained constant over the sampling period and were not correlated to embryonic size. Likewise, endometrial concentrations of P4 (66.1 ± 6.5 ng/g), E2 (284.0 ± 24.43 pg/g) and, Etot (440.9 ± 24.43 pg/g) showed no changes over time [corrected]. Therefore, it was concluded that ovarian steroid hormones do not play a determining role in resumption of embryonic growth following the period of diapause in the roe deer.
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Affiliation(s)
- Barbara Drews
- ETH Zurich, Animal Physiology, Institute of Agricultural Sciences, Switzerland
| | - Alba Rudolf Vegas
- ETH Zurich, Animal Physiology, Institute of Agricultural Sciences, Switzerland
| | | | - Vladimir Milojevic
- ETH Zurich, Animal Physiology, Institute of Agricultural Sciences, Switzerland
| | | | - Gerhard Schuler
- Clinic for Veterinary Obstetrics, Gynecology and Andrology of Large and Small Animals, Justus-Liebig-University, Giessen, Germany
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Carlsson AM, Mastromonaco G, Vandervalk E, Kutz S. Parasites, stress and reindeer: infection with abomasal nematodes is not associated with elevated glucocorticoid levels in hair or faeces. CONSERVATION PHYSIOLOGY 2016; 4:cow058. [PMID: 27957334 PMCID: PMC5147723 DOI: 10.1093/conphys/cow058] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 10/28/2016] [Accepted: 11/13/2016] [Indexed: 05/30/2023]
Abstract
Stress hormones (glucocorticoids), incorporated into hair/fur and faeces, have been proposed as biomarkers of overall health in wildlife. Although such biomarkers may be helpful for wildlife conservation and management, their use has rarely been validated. There is a paucity of studies examining the variation of stress hormones in mammals and how they relate to other health measures, such as parasitism. Parasites are ubiquitous in wildlife and can influence the fitness of individual animals and populations. Through a longitudinal experiment using captive reindeer (Rangifer tarandus tarandus), we tested whether animals infected with Ostertagia gruehneri, a gastrointestinal nematode with negative impacts on fitness of the host, had higher stress levels compared with those that had been treated to remove infection. Faecal samples were collected weekly for 12 weeks (June-September) and hair was collected at the start and end of the study; glucocorticoids were quantified using enzyme immunoassays. Contrary to what was expected, infected reindeer had similar levels of cortisol in hair and slightly lower glucocorticoid metabolites in faeces compared with uninfected reindeer. Faecal corticosterone levels were higher than faecal cortisol levels, and only corticosterone increased significantly after a handling event. These results suggest that reindeer may use a tolerance strategy to cope with gastrointestinal nematodes and raise the question as to whether moderate infection intensities with nematodes are beneficial to the host. By removing nematodes we may have altered the gut microbiota, leading to the observed elevated faecal glucocorticoid metabolite levels in the treated reindeer. These findings demonstrate the importance of considering both cortisol and corticosterone in physiological studies, as there is mounting evidence that they may have different functionalities.
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Affiliation(s)
- A. M. Carlsson
- Department of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, 3280 Hospital Drive NW, Calgary, Alberta, CanadaT2N 4Z6
| | - G. Mastromonaco
- Reproductive Physiology Unit, Toronto Zoo, 361A Old Finch Avenue, Scarborough, Ontario,CanadaM1B 5K7
| | - E. Vandervalk
- Department of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, 3280 Hospital Drive NW, Calgary, Alberta, CanadaT2N 4Z6
| | - S. Kutz
- Canadian Cooperative Wildlife Health Centre Alberta, 3280 Hospital Drive NW, Calgary, AB T2N4Z6, Canada
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Chen X, Wei H, Yang Y, Xue H, Zhao W, Zhao M. Serum hormone concentrations and ovarian follicular wave emergence in Jilin sika deer (Cervus nippon hortulorum) after synchronization of estrous cycles. Anim Reprod Sci 2015; 153:44-9. [DOI: 10.1016/j.anireprosci.2014.11.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Revised: 11/20/2014] [Accepted: 11/24/2014] [Indexed: 11/26/2022]
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Yanagawa Y, Matsuura Y, Suzuki M, Saga SI, Okuyama H, Fukui D, Bando G, Nagano M, Katagiri S, Takahashi Y, Tsubota T. Accessory corpora lutea formation in pregnant Hokkaido sika deer (Cervus nippon yesoensis) investigated by examination of ovarian dynamics and steroid hormone concentrations. J Reprod Dev 2014; 61:61-6. [PMID: 25482110 PMCID: PMC4353723 DOI: 10.1262/jrd.2014-076] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Generally, sika deer conceive a single fetus, but approximately 80% of pregnant females have two corpora lutea (CLs). The function of the accessory CL (ACL) is unknown; moreover, the process of ACL formation is unclear, and understanding this is necessary to know its role. To elucidate the process of ACL formation, the ovarian dynamics of six adult Hokkaido sika deer females were examined ultrasonographically together with peripheral estradiol-17β and progesterone concentrations. ACLs formed in three females that conceived at the first estrus of the breeding season, but not in those females that conceived at the second estrus. After copulation, postconception ovulation of the dominant follicle of the first wave is induced by an increase in estradiol-17β, which leads to formation of an ACL. A relatively low concentration of progesterone after the first estrus of the breeding season is considered to be responsible for the increase in estradiol-17β after copulation.
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Affiliation(s)
- Yojiro Yanagawa
- Laboratory of Theriogenology, Graduate School of Veterinary Medicine, Hokkaido University, Hokkaido 060-0818, Japan
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Ginther OJ. How ultrasound technologies have expanded and revolutionized research in reproduction in large animals. Theriogenology 2014; 81:112-25. [PMID: 24274416 DOI: 10.1016/j.theriogenology.2013.09.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 09/06/2013] [Accepted: 09/07/2013] [Indexed: 01/26/2023]
Abstract
Gray-scale ultrasonic imaging (UI) was introduced in 1980 and initially was used to examine clinically the reproductive tract of mares. By 1983 in mares and 1984 in heifers/cows, UI had become a tool for basic research. In each species, transrectal gray-scale UI has been used extensively to characterize follicle dynamics and investigate the gonadotropic control and hormonal role of the follicles. However, the use of transrectal UI has also disclosed and characterized many other aspects of reproduction in each species, including (1) endometrial echotexture as a biological indicator of circulating estradiol concentrations, (2) relative location of the genital tubercle for fetal gender diagnosis by Days 50 to 60, and (3) timing of follicle evacuation during ovulation. Discoveries in mares include (1) embryo mobility wherein the spherical conceptus (6-16 mm) travels to all parts of the uterus on Days 11 to 15, (2) how one embryo of a twin set eliminates the other without self-inflicted damage, and (3) serration of the granulosum of the preovulatory follicle opposite to the future rupture site as an indicator of imminent ovulation. Studies with color-Doppler UI have shown that vascular perfusion of the endometrium follows the equine embryo back and forth between uterine horns and follows the expansion of the bovine allantochorion throughout each horn. In heifers, blood flow in the CL increases during the ascending portion of an individual pulse of PGF2α metabolite and then decreases. These examples highlight the power of UI in reproduction research. Without UI, it is likely that these and many other findings would still be unknown.
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Affiliation(s)
- O J Ginther
- Eutheria Foundation, Cross Plains, Wisconsin, USA; Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, Wisconsin, USA.
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McCorkell RB, Woodbury MR, Adams GP. Serial ovarian ultrasonography in wild-caught wood bison (Bison bison athabascae). Theriogenology 2013; 80:552-6. [DOI: 10.1016/j.theriogenology.2013.05.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Revised: 05/28/2013] [Accepted: 05/29/2013] [Indexed: 11/25/2022]
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McCorkell RB, Woodbury MR, Adams GP. Superovulation in waptiti (Cervus elaphus) during the anovulatory season. Theriogenology 2013; 79:24-7. [DOI: 10.1016/j.theriogenology.2012.09.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2011] [Revised: 09/03/2012] [Accepted: 09/07/2012] [Indexed: 10/27/2022]
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Powers JG, Baker DL, Ackerman MG, Bruemmer JE, Spraker TR, Conner MM, Nett TM. Passive transfer of maternal GnRH antibodies does not affect reproductive development in elk (Cervus elaphus nelsoni) calves. Theriogenology 2012; 78:830-41. [PMID: 22541328 DOI: 10.1016/j.theriogenology.2012.03.033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 03/12/2012] [Accepted: 03/20/2012] [Indexed: 11/16/2022]
Abstract
Gonadotropin-releasing hormone is intermittently released from the hypothalamus in consistent patterns from before birth to final maturation of the hypothalamic-pituitary-gonadal axis at puberty. Disruption of this signaling via GnRH vaccination during the neonatal period can alter reproduction at maturity. The objective of this study was to investigate the long-term effects of GnRH-antibody exposure on reproductive maturation and function in elk calves passively exposed to high concentrations of GnRH antibodies immediately after birth. Fifteen elk calves (eight males and seven females) born to females treated with GnRH vaccine or sham vaccine during midgestation were divided into two groups based on the concentration of serum GnRH antibodies measured during the neonatal period. Those with robust (>15 pmol (125)I-GnRH bound per mL of serum) titers (N = 10; four females and six males) were designated as the exposed group, whereas those with undetectable titers (N = 5; three females and two males) were the unexposed group. Onset of puberty, reproductive development, and endocrine function in antibody-exposed and unexposed male and female elk calves were compared. Neonatal exposure to high concentrations of GnRH antibodies had no effect on body weight (P = 0.968), endocrine profiles (P > 0.05), or gametogenesis in either sex. Likewise, there were no differences between groups in gross or histologic structure of the hypothalamus, pituitary, testes, or ovaries. Pituitary stimulation with a GnRH analog before the second potential reproductive season induced substantial LH secretion in all experimental elk. All females became pregnant during their second reproductive season and all males exhibited similar mature secondary sexual characteristics. There were no differences between exposure groups in hypothalamic GnRH content (P = 0.979), pituitary gonadotropin content (P > 0.05) or gonadal structure. We concluded that suppressing GnRH signaling through immunoneutralization during the neonatal period likely does not alter long-term reproductive function in this species.
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Affiliation(s)
- J G Powers
- Colorado State University, Animal Reproduction and Biotechnology Laboratory, Fort Collins, Colorado, USA.
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Powers JG, Baker DL, Davis TL, Conner MM, Lothridge AH, Nett TM. Effects of gonadotropin-releasing hormone immunization on reproductive function and behavior in captive female Rocky Mountain elk (Cervus elaphus nelsoni). Biol Reprod 2011; 85:1152-60. [PMID: 21753192 DOI: 10.1095/biolreprod.110.088237] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Fertility control is a potential method for managing overabundant wildlife populations; however, current technology is limited by duration of treatment efficacy and unacceptable side effects. The objective of this study was to determine the efficacy of a single immunization with gonadotropin-releasing hormone (GnRH) vaccine to suppress reproductive function in pregnant female elk and to evaluate potential behavioral and pathological side effects of treatment. Eighteen captive adult female elk were randomly allocated to one of two experimental groups. Ten females were administered a conjugated and adjuvanted GnRH vaccine intramuscularly, and eight elk received an adjuvant sham vaccine without conjugated GnRH. We compared success of existing pregnancy, neonatal survival, subsequent fertility, reproductive behavior rates, and side effects of treatment between January 2006 and January 2010. The GnRH vaccination did not affect existing pregnancy or calf survival during the year that it was applied; however, it reduced the proportion of pregnant females for 3 yr. Male precopulatory behavior rates exhibited toward GnRH-vaccinated females tended to be greater than those directed at sham-vaccinated females during the second half of the breeding season, when GnRH vaccinates continued to be proceptive. Strong immune and inflammatory responses, including robust GnRH antibody concentrations in GnRH vaccinates, and sterile pyogranulomatous injection site abscesses in both groups, were consistent with vaccination. In conclusion, this GnRH vaccine resulted in prolonged, albeit reversible, impairment of fertility, and is associated with extended reproductive behaviors and partial suppression of hypothalamic-pituitary-gonadal axis function in captive female elk.
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Affiliation(s)
- Jenny G Powers
- Animal Reproduction and Biotechnology Laboratory, Colorado State University, Fort Collins, Colorado, USA.
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Mohammadpour AA. Comparative histomorphological study of ovary and ovarian follicles in Iranian Lori-Bakhtiari sheep and native goat. Pak J Biol Sci 2008; 10:673-5. [PMID: 19069557 DOI: 10.3923/pjbs.2007.673.675] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
In this project, for measuring and comparing dimensions of ovary and ovarian follicles between Lori-Bakthiari sheep and native goat, eighty ovaries of sheep and goat, aged 1-2 years, from Shahrekord abattoir were collected. After weighing the ovaries, some factors such as: length, width and thickness of left and right ovaries by caliper device were measured. For histological studies, after tissue preparation and staining with H and E, diameter of follicles, thickness of follicular layers (granulosa, theca interna and theca externa) by micrometry methods were measured. By analyzing data with t-test and comparing them between sheep and goat we concluded that, there were significant difference between weight and dimensions of ovaries in sheep and goat. These parameters in goats were larger than sheep. Microscopical studies revealed that, the mean thickness of theca externa of graafian follicle in left ovary of sheep was more than right. The mean diameter of oocyte in secondary follicle of goat in left ovary was more than right. Also in goat, the number of layers of cumulus oophorus around corona radiata was more than sheep.
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Affiliation(s)
- A A Mohammadpour
- Department of Basic Sciences, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, P.O. Box 1793, Mashhad, Iran
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McCorkell RB, Woodbury MR, Adams GP. Induction of ovarian follicular wave emergence in wapiti (Cervus elaphus). Theriogenology 2008; 70:1017-23. [PMID: 18706684 DOI: 10.1016/j.theriogenology.2008.04.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2008] [Revised: 04/14/2008] [Accepted: 04/15/2008] [Indexed: 11/17/2022]
Abstract
Two experiments were done to test the effects of treatments designed to electively induce ovarian follicular wave emergence in wapiti for the purpose of group synchronization. In Experiment 1, hinds were assigned randomly to three groups and given saline im (controls; n=5), 5mg of estadiol-17beta im (n=4), or 5mg estradiol-17beta plus 100mg progesterone im (n=5). In Experiment 2, hinds were assigned randomly to two groups and given no treatment (controls; n=6), or transvaginal ultrasound-guided follicle ablation (n=7). In both experiments, ovarian follicular dynamics were monitored by daily transrectal ultrasonography from Day 0 (day of treatment) to Day 9. In Experiment 1, blood samples were collected at each examination for measurement of serum concentrations of progesterone and FSH. Both experiments were conducted during the late anestrous period (July and August). The mean (+/-S.E.M.) day of wave emergence did not differ between the control and estradiol alone groups, but tended to be later in the estradiol plus progesterone group Day 4.0+/-0.7, Day 3.5+/-0.3, and Day 5.2+/-0.2, respectively; P=0.06). The interval from treatment to wave emergence was less variable in the estradiol plus progesterone group (P<0.05) and tended to be less variable in the estradiol-alone group (P=0.07) than in the control group. The day of wave emergence was more variable (P<0.05) and tended to be later (P=0.10) in the control group compared to the ablation group (Day 2.5+/-0.8 versus Day 1.4+/-0.2). All three treatments were effective in synchronizing ovarian follicular wave emergence among a group of wapiti hinds. Follicle ablation may be an alternative method for synchronization of follicular waves in estrus synchronization and superstimulatory protocols.
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Affiliation(s)
- R B McCorkell
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4, Canada.
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McCorkell R, Woodbury MR, Adams GP. Ovarian follicular and luteal dynamics in wapiti during seasonal transitions. Theriogenology 2007; 67:1224-32. [PMID: 17331569 DOI: 10.1016/j.theriogenology.2007.01.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2006] [Revised: 12/05/2006] [Accepted: 01/06/2007] [Indexed: 12/01/2022]
Abstract
Transitions from the anovulatory to the ovulatory season (n=20) and ovulatory to anovulatory season (n=11), were monitored daily by transrectal ultrasonography in wapiti. In 17 of 20 observations, the first interovulatory interval (IOI) was short (9.1+/-0.3 days; mean+/-S.E.M.) compared with later in the ovulatory season (21.3+/-0.1) and the last IOI (21.2+/-0.6 days). With one exception, the short IOI were composed of only one wave of follicular development. Subsequent IOI were composed of two or three waves. Maximum diameters of the first two ovulatory follicles were similar (11.3+/-0.4 mm versus 11.3+/-0.2 mm), but both were larger (P<0.05) than the last two ovulatory follicles of the ovulatory season (10.3+/-0.3 and 10.1+/-0.4 mm). Multiple ovulations occurred in three hinds at the first ovulation of the season and in one hind at the second ovulation, but were not at any other time. Day-to-day profiles of CL diameter and plasma progesterone concentration were smaller (P<0.05) for short versus long IOI. Maximum diameter (12.8+/-0.6 mm versus 12.5+/-0.6 mm) and the diameter profile of the last CL of the season were not different from that of the previous CL. In summary, transition to regular ovulation occurred over a 3-week interval and was preceded by one short IOI (9 days). Multiple ovulations were detected only at the onset of the ovulatory season. The characteristics of the last IOI of the ovulatory season were similar to those reported during the rut. The wave pattern of follicle development was maintained throughout both fall and winter transition periods and follicular wave emergence was preceded by a surge in serum FSH concentrations. Transition to anovulation occurred over a 3-month interval and was marked by a failure of the dominant follicle to ovulate after a typical luteal phase.
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Affiliation(s)
- R McCorkell
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4, Canada.
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McCorkell RB, Woodbury MR, Adams GP. Evaluation of an ovarian synchronization scheme for fixed-time artificial insemination in wapiti. Theriogenology 2007; 67:1217-23. [PMID: 17331570 DOI: 10.1016/j.theriogenology.2007.01.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2006] [Revised: 12/03/2006] [Accepted: 01/06/2007] [Indexed: 11/17/2022]
Abstract
The ovarian response to an empirically derived treatment protocol used commercially for fixed-time insemination in wapiti (Cervus elaphus) was evaluated by transrectal ultrasonography in hinds during transition into the ovulatory season. On September 29, hinds (n=7) were given an intravaginal progesterone-releasing device (CIDR-B, 1.9 g of progesterone) or left untreated (controls, n=9). Fourteen days later, hinds in the treated group were given 200 IU eCG and the CIDR was removed. Hinds in the control group ovulated randomly over a 15 day period. In the treated group, five hinds ovulated 3 days after eCG treatment, one ovulated 7 days after treatment, and one failed to ovulate by November 1. All extant dominant follicles ceased growth and/or began to regress within 2 days of CIDR placement. Two waves of follicular development were detected between CIDR insertion and removal; the first emerged 5.1+/-0.5 days after CIDR insertion and the second at 11.0+/-0.7 days. Serum progesterone concentration was 0.6+/-0.5 ng/mL (range 1.0-0.3 ng/mL) before CIDR placement, remained above 6 ng/mL during CIDR placement, and fell to 0.8+/-0.9 ng/mL after CIDR removal. In the control group, maximal luteal-phase progesterone concentration was lower (1.1+/-0.1 ng/mL; P<0.05) and emergence of the first follicular wave was more variable (P=0.05) than in the treated group. The protocol to synchronize ovulation was effective in 5/7 (71%) hinds, and 4/7 (57%) became pregnant and calved. The pregnancy rate (6/9) and calving rate (5/9) was similar in the control group. In conclusion, synchronization with CIDR-B was effective; however, the protocol may be improved by shortening the interval of CIDR placement to < or = 7 days and by reducing the circulating concentrations of progesterone to physiologic concentrations (< 4 ng/mL).
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Affiliation(s)
- R B McCorkell
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4, Canada.
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McCorkell R, Woodbury M, Adams GP. Ovarian follicular and luteal dynamics in wapiti during the estrous cycle. Theriogenology 2006; 65:540-56. [PMID: 16009414 DOI: 10.1016/j.theriogenology.2005.05.049] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2005] [Accepted: 05/18/2005] [Indexed: 10/25/2022]
Abstract
The reproductive tracts of 13 mature hinds were examined daily by transrectal ultrasonography and blood samples were taken daily from October to January to characterize follicular, luteal, and endocrine dynamics in wapiti during the estrous season. Follicle development occurred in waves characterized by regular, synchronous development of a group of follicles in temporal succession to a surge in serum FSH concentration. The mean interovulatory interval was 21.3 +/- 0.1 d, but was shorter in hinds exhibiting two follicular waves than in hinds exhibiting three and four waves (P < 0.05). The interwave interval was similar among waves in two-wave cycles and the first wave of three-wave cycles. All other interwave intervals in three- and four-wave cycles were shorter (P < 0.05). The maximum diameter of the dominant follicle of the first wave was similar among two-, three-, and four-wave cycles. For all other waves in three- and four-wave cycles, the maximum diameter was smaller (P < 0.05). Corpus luteum diameter and plasma progesterone concentrations were similar between two- and three-wave cycles, but the luteal phase was longer (P < 0.05) in four-wave cycles. The dominant follicle emerged at a diameter of 4 mm at 0.4 +/- 0.1 and 0.8 +/- 0.1 d before the largest and second largest subordinate follicles, respectively. The follicle destined to become dominant was larger (P < 0.05) than the largest subordinate follicle one day after emergence, which coincided with the first significant decrease in serum FSH concentration. We concluded that the estrous cycle in wapiti is characterized by two, three, or four waves of follicular development (each preceded by a surge in circulating FSH), that there is a positive relationship between the number of waves and the duration of the cycle, and an inverse relationship between the number of waves and the magnitude of follicular dominance (diameter and duration of the dominant follicle).
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Affiliation(s)
- Robert McCorkell
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, Sask., Canada S7N 5B4
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