Pregnancy in horses, or equine gestation, is a physiological process that involves the development of a foal within the mare over approximately 11 months. This period is characterized by distinct stages, including fertilization, embryonic development, and fetal growth. Throughout gestation, mares undergo various physiological and hormonal changes to support the developing fetus. Monitoring pregnancy in horses involves assessing fetal health and mare well-being through veterinary examinations and diagnostic tools such as ultrasound. This page compiles peer-reviewed research studies and scholarly articles that explore the physiological processes, management practices, and health considerations associated with equine pregnancy.
Nett TM, Holtan DW, Estergreen VL.Levels of oestrone, equilin and equilenin (E1), oestradiol (E2) LH, PMSG and prolactin were measured by radioimmunoassay in serum from pregnant mares. Levels of E1 were always greater than those of E2. Both E1 and E2 remained at low levels until Day 80, increased significantly (P less than 0-05) by Day 120 to reach peak levels at Day 210 or 240 and then declined until parturition. Maximum levels of oestrogens observed in this study were 828 +/- 151 pg/ml for E1 and 71 +/- 18 pg/ml for E2 at Days 210 and 240 respectively. Spikes of LH release were observed in early pregnancy in most mares. Leve...
Cox JE.A method for the extraction of oestrone and equilin from the plasma of the pregnant mare is described, and the levels obtained for eighty-two samples from fourteen Welsh Mountain Ponies at different stages of pregnancy are recorded. Oestrone (fifteen samples) and equilin (three samples) were not found before Day 120. From Day 120 to 240, oestrone levels exceeded 100 ng/ml and then declined to parturition. The high concentrations of oestrone in mid-pregnancy were associated with gradually increasing concentrations of equilin which tended to plateau after Day 180 at just under 100 ng/ml and decl...
Irwin CF.A total of 487 Standardbred and Thoroughbred mares at two studs were manually tested for pregnancy at 20 to 24, 30 to 34, and greater than 42 days after service and the abortion rate compared to that obtained in previous years when only the greater than 42-day test was performed. The results indicated that early manual pregnancy testing does not increase the abortion rate if undertaken carefully and enables non-pregnant mares to be re-mated earlier in the same season.
Deanesly R.A histological study of the developing germinal epithelium in the fetal horse ovary shows an enormous wastage of oocytes during the meiotic phase, between Days 73 and 150 of pregnancy. The first groups of oocytes to enter this phage undergo mass degeneration and eventually disappear; few, if any, oocytes develop to primordial follicles. Peripheral oogonia, dividing by mitosis, give rise to more oocytes which pass through the same changes and are also reduced by degeneration, but by Day 150 primordial follicles are fairly common.
Merkt H, Klug E, Krause D, Bader H.Stallion semen frozen by the pellet method showed no significant loss of sperm motility and fertility over long periods of storage in liquid nitrogen. Eighteen of thirty mares conceived after insemination with semen recovered in nine ejaculates from seven stallions and stored for 18 months to 7 years.
Hillman RB.Thirty-seven induced parturitions involving thirty-one mares were studied over a 2-year period using various doses of oestrogen and oxytocin. The time of appearance and degree of expression of the major clinical signs of parturition, and the time for completion of delivery and the passage of the placenta were significantly influenced by increasing doses of oxytocin. Oestrogen was useful in softening and relaxing the cervix when it was tight, but was not essential to induction when the cervix was already soft and dilating. Fertility was not adversely affected by induced parturition.
Klug E, Treu H, Hillmann H, Heinze H.Artificial insemination using deep-frozen semen was performed on 116 mares in 1973 using twelve ejaculates from eight stallions of the Hanoverian breed. Despite the fact that the quality of the semen used was poor, the majority of the mares inseminated were subfertile and some mares were inseminated during one oestrus only, 44% nevertheless conceived and gave birth to live foals. Of a small group of ten mares inseminated in the same year with fresh semen, seven conceived.
Belonje PC, van Niekerk CH.Attention is drawn to the beneficial effect of improved nutrition during winter and early spring on the ovarian activity of mares. Furthermore, the necessity of an adequate plane of nutrition during early pregnancy to prevent embryonic resorption is stressed.
Allen WR, Rowson LE.Surgical and non-surgical methods used for the recovery and transfer of fertilized horse eggs are described. Sixteen of the twenty-three zygotes recovered surgically between Days 1 to 6 after ovulation from thirty donor mares were transferred surgically to synchronized recipients; seven pregnancies resulted. Seven of the eleven zygotes recovered non-surgically between Days 6 to 8 after ovulation from twenty-eight donor mares were transferred non-surgically to synchronized recipients; five pregnancies resulted.
Short RV.The infertility of the mule has proved a continuing challenge to scientific thought. Since the chromosomal differences between the two parental species are so great as to render normal meiosis impossible, it is postulated that all mules and hinnies are sterile. The problem now is to explain how mules and hinnies can occasionally produce spermatozoa or ova. The appearance of the mule was sufficient to persuade the ancients that both parents, not just the male, must contribute to the make-up of the offspring. The mule has also taught us that, when the number of oocytes in the ovary is reduced, t...
Jeffcott LB.The mechanism of transfer of maternal immunity to the foal is reviewed. Maximal efficiency of macromolecular absorption by specialized cells of the small intestine exists soon after birth. The absorptive cells are progressively replaced by more mature-looking cells incapable of taking up large molecules and the rate of absorption is reduced in a linear decline and ceases completely within 24 hr. Passive antibody levels fall rapidly in the first 4 weeks of life to less than half their original values and have usually completely disappeared by 6 months of age. The foal shows immunological compet...
Barnes RJ, Nathanielsz PW, Rossdale PD, Comline RS, Silver M.Normal Thoroughbred and catheterized Pony mares and their fetuses were used. Fetal oestrogen and progestagen concentrations in late gestation were much higher than maternal values. A major feature of the umbilical steroid concentrations was a large venous-arterial difference in progestagens and total oestrogens throughout late gestation which may indicate a metabolic cycle in the fetus between progesterone and other steroid metabolites. Metabolites of 20alpha-dihydroprogesterone were present in high concentrations in maternal and fetal plasma. In Thoroughbreds, and to a lesser extent in Pony m...
Arvidson G, Astedt B, Ekelund L, Rossdale PD.Phospholipids in embryonic lung tissue, pulmonary washings and amniotic fluid were measured to study the development of lyng surfactant in the horse. A significant increase in the concentration of total phospholipids in lung tissue and a concomitant rise in the amount of dipalmitoyl lecithin in amniotic fluid between 100 and 150 days of gestation indicated the initial formation of surfactant in the fetal lung during this period.
Douglas RH, Ginther OJ.Prenatal specimens from mares with known breeding dates were used to characterize morphological changes in the fetus and placenta of pony mares. Prenatal characteristics and the day on which each was first found and weights of different components of the equine conceptus are summarized.
Parker WG, Sullivan JJ, Larson LL.The diagnostic value of rectal palpation and immunological assay of PMSG was tested at different stages of pregnancy in mares inseminated with frozen semen in three separate studies. The results were based on foaling success and particular attention was paid to the numbers of inconsistent results obtained by the two tests. Generally, the number of false positive diagnoses was lower for the immunological assay than for palpation in early pregnancy (Days 40 to 60) and the relationship became reversed later in gestation.
Samuel CA, Allen WR, Steven DH.Microcotyledons, which are a distinctive feature of the mature equine placenta, are fully formed by Day 150 of gestation. The fetal component of each microcotyledon is developed from several primary folds of trophoblast which become elaborately subdivided as gestation proceeds. These changes are reflected in the structure of the maternal crypts, which receive the fetal villi. Between Days 60 and 150 of gestation the maternal epithelium is greatly reduced in height. No such change occurs on the fetal side of the placenta, but between Days 100 and 250 a progressive indentation of the epithelium ...
Lovell JD, Stabenfeldt GH, Hughes JP, Evans JW.The levels of progesterone and total progestins increased during late pregnancy and then fell dramatically during the last few days before parturition, although birth occurred in the presence of significant amounts of plasma progesterone. Oestrogen levels decreased slowly but insignificantly until birth occurred, and then remained at a low level until the post-partum oestrus 10 to 12 days later. Total 11beta-hydroxycorticosteroids were unchanged from Day 45 before to Day 15 after birth. The endocrine pattern of one ovariectomized pregnant mare during the last month of gestation was similar to ...
Marrable AW, Flood PF.A sequence of ten known-age embryos recovered from Dartmoor Ponies during the first 4 months of gestation is described. Changes in size, shape and vascularity of the conceptus are recorded, as well as the growth and decline of the yolk-sac and the succeeding establishment of the allantochorion. The progress of equine somatogenesis is compared with that of the pig which it lags on average of about 4 days. Some quantitative data are presented.
Raeside JI, Liptrap RM.Urine collections (24 hr) were made at weekly intervals from four Pony mares from the 3rd or 4th month of pregnancy until parturition. Separation of oestrogens on Celite columns was followed by Kober measurements of oestrone and equilin. Individual differences were noted in peak amounts of total oestrogens excreted (200 to 800 mg/day), when oestrone constituted 80 to 95% at the 6th to 7th months. Although equilin increased in later gestation, oestrone remained the major product. Total oestrogen values decreased rapidly from the peak and then more gradually towards the end of pregnancy. During ...
Burns SJ, Fleeger JL.Plasma progestagens were measured in eighteen pregnant mares to establish normal levels in the first and last 90 days of gestation. Progestagens increased from 25 ng/ml at 90 days before birth to 60 ng/ml at 10 days before birth, decreased to 58 ng/ml at 5 days before, and were 3 ng/ml or less by 5 days after perturition. During the first 90 days of pregnancy, progestagens reflected luteal activity with an increase in plasma levels from Day 30 to Day 60.
Onuma H, Ohnami Y.Genital tracts from 227 mares slaughtered in various reproductive states were investigated to study egg retention in the oviducts. Eggs were found in 88-2% of 212 non-pregnant mares; the number/mare ranged from 0 to 21, and averaged 4-34. Retained eggs were twice as common in heavy as in light breeds and were found more frequently in early than in late pregnancy. Eggs were not found in the oviducts of two anovulatory post-partum mares. A few globular masses, probably consisting of desquamated tubal mucosa, were frequently lodged in the distal region of the ampulla and appeared, to some extent ...
Squires EL, Ginther OJ.Examination of the ovaries of mares at various stages of pregnancy and after hysterectomy, together with measurement of progesterone concentrations in the peripheral plasma of pregnant and hysterectomized mares and in uterine and ovarian venous plasma of pregnant mares, demonstrated that the primary CL of pregnancy remains functional until at least Day 160 of gestation. The results showed that primary and secondary CL, and the placenta or uterus, all contribute to the total progesterone pool in mares during pregnancy. Similarities and differences in ovarian function observed between pregnant a...
Samuel CA, Allen WR, Steven DH.The various cell types in the adult anterior pituitary may be distinguished at the ultrastructural level of the sizes of the secretory granules within the cytoplasm. In the fetal adenohypophysis, with the exception of prolactin-producing cells, all types may be identified after Day 100 of gestation. Morphological evidence suggests that they are producing and secreting trophic hormones. The three constituent layers of the adrenal cortex are also discernible by Day 100 of pregnancy. The cells of the zona glomerulosa have large numbers of darkly stained inclusions within the cytoplasm. The zona f...
Kitchen H, Bunn HF.Studies were made of the O2 affinities of fetal and maternal haemoglobins in the horse, and correlations were found with erythrocytic levels of 2,3-diphosphoglycerate.
Steven DH, Samuel CA.The study of the equine placenta, which began in Venice in 1598, has a long but discontinuous history. Early observations were purely morphological, but new techniques have stimulated a broader and more functional approach. Histological and ultrastructural observations at various stages of pregnancy have shown that the fetal side of the placenta comes to acquire certain features in common with the air-blood barrier of the mammalian lung. These changes may reflect the increasing O2 requirements of the fetus as gestation proceeds.
Hernández-Jáuregui , González-Angulo A.Electron microscopy and immunofluorescence techniques were used to study the various epithelial cells in the endometrial cups of ten pregnant mares, and in the uterine epithelium of one non-pregnant mare. Evidence was obtained which suggested that epithelial gland cells within the endometrial cups, as distinct from the hypertrophied decidual-like cells in the cup, may synthesize PMSG. The suggestion does not agree with the findings of other workers in the fetal origin (chorionic girdle cells) of this gonadotrophin.
Ferreira JRM, Villela SB, Bianconi C, Ormieres M, de Melo GD, Pugliesi G, Gobesso AAO.Different approaches have been used to improve conception rates at foal heat. Omega-3 fatty acids family and derivatives have improved reproductive efficiency in ruminants, but literature lacks studies evaluating these components on equines. The objective of this study was to evaluate effects of mare dietary supplementation with microalgae rich in docosahexaenoic acid (DHA) during peripartum on follicular dynamics and uterine involution in early post-partum. Eighteen pregnant mares, no particular breed, 410 ± 39.5 kg body weight (BW), and 7.83 ± 2.01 yr old were used. Mares were randomly ass...
Wynn MAA, Ball BA, Legacki E, Conley A, Loux S, May J, Esteller-Vico A, Stanley S, Scoggin K, Squires E, Troedsson M.In the latter half of gestation in the mare, progesterone concentrations decline to near undetectable levels while other 5α-reduced pregnanes are elevated. Of these, 5α-dihydroprogesterone and allopregnanolone have been reported to have important roles in either pregnancy maintenance or fetal quiescence. During this time, the placenta is necessary for pregnane metabolism, with the enzyme 5α-reductase being required for the conversion of progesterone to 5α-dihydroprogesterone. The objectives of this study were to assess the effects of a 5α-reductase inhibitor, dutasteride on pregnane metab...
Ginther OJ, Douglas RH, Lawrence JR.Responses of 22 veterinarians to a questionnaire and the records of three brood-mare farms were examined to obtain information on twinning. The incidence rates of multiple ovulations on the three farms were 9%, 11%, and 22%. The multiple ovulation rate was reduced 42-67% in foaling mares compared to barren and maiden mares. Multiple ovulations were significantly more frequent in Thoroughbreds (19%) than in Quarter Horses (9%) and Appaloosas (8%). Both the questionnaire and the farm records indicated a high degree of repeatability of multiple ovulations and twin pregnancies within mares and wit...
Bucca S, De Oliveira IRS, Cunanan JC, Vinardell T, Troedsson MHT.Assessment of pregnancy viability in the equine patient is currently based on gestational profiles of limited prognostic value. In recent years Doppler technology has been applied to uterine and umbilical arteries of pregnant mares to monitor fetal responsive haemodynamics, suggestive of compromise. To date, uterine artery Doppler indices failed to provide sufficient evidence of pregnancy viability and the umbilical cord of the equine fetus is inconsistently visualized past 250 days gestation. The objectives of this study were to: i) evaluate intracranial blood flow impedance by Doppler examin...
Sevinga M, Hesselink JW, Barkema HW.Because the incidence of retained placenta in Friesian mares is estimated to be high, and no reports have been published on the reproductive performance of Friesian mares after retained placenta, we studied postpartum reproductive performance in Friesian brood mares with (n = 54) and without (n = 50) retained placenta. We defined a retained placenta as the failure to expel all fetal membranes within 3 h after the delivery of a foal. We subdivided the group of mares with retained placenta into mares in which the placenta had been removed manually (n = 30) and mares in which it had not (n = 24)....
Hannan MA, Haneda S, Murata K, Takeuchi S, Cheong SH, Nambo Y.Until now, there have been no reports of foals born through embryo transfer after artificial insemination using frozen semen in Japan. The aims of this study were to develop a riding crossbred horse and evaluate the prospects of embryo transfer technology in multiplying horse population. In both donor and recipient mares, luteolysis was induced by the administration of 0.1 mg Cloprostenol to synchronize the onset of estrus, and ovulation was induced by administering 2000 IU human chorionic gonadotropin (hCG) or 0.75 mg Deslorelin. Frozen semen from an Irish Connemara pony stallion was used to ...
Meier HP, Gertsch U, Kohler S.Twin pregnancies are a serious problem in stud medicine as they terminate in most cases in abortion, stillbirth or the delivery of dead or weak and deformed foals. In recent years, the introduction of sonography has greatly improved the management of mares with twin conceptuses, in particular monitoring the phenomenon of spontaneous embryo reduction to a single vesicle. This allows supervision of pregnancy with relatively little expenditure and loss of time. We document the spontaneous reduction to single vesicles of unilateral twin pregnancies in a draught- and a warmblood-mare. In both mares...
Rua MAS, Quirino CR, Rodrigues ACC, Christo MM, Barreto MAP.The objective of this study was to evaluate the environmental effects on embryo recovery rate and pregnancy rate of Mangalarga Marchador mares. The reproductive characteristics of donor and recipient mares were evaluated during five years in Brazilian tropical environment. The mares were used throughout the year and seasons were classified as: October to April (breeding season - BS); May (autumn transition out of the breeding season - ATBS); June to August (non-breeding season - nBS); and September (vernal transition into the breeding season - VTBS). Daily temperature rainfall and hours of day...
Salari F, Licitra R, Altomonte I, Martini M.We evaluated the daily intake in donkeys during maintenance, late pregnancy, and early lactation. The growth curves of the foals in the first eight weeks of life and the milk production in lactating jennies were also investigated. Donkeys were separated into two groups: seven pregnant jennies (group 1: pregnant/lactating) and seven nonpregnant, nonlactating jennies (group 2). The groups were fed two different diets each. The feeding period for group 1 covered eight weeks before parturition and eight weeks postpartum. Group 2 was managed during the same time period (16 weeks). Diet 1 consisted...
Wilsher S, Allen WR.Eight day 10 horse embryos were transferred non-surgically to recipient mares that had ovulated 7 days after the donors. The embryonic vesicle was seen ultrasonographically in all eight recipients, and three out of eight (38%) of the vesicles developed an embryo proper with a beating heart. Conceptus expansion was initially slower than that in control mares but continued until day 22 (recipient day 15). Time of fixation of the vesicle was related to its diameter, rather than uterine stage. Although the embryo proper first appeared ultrasonographically on day 22, as normal, it grew more slowly ...
Jedruch J, Gajewski Z, Kuussaari J.The effect of detomidine on the electrical activity of the uterus was studied during the last trimester of pregnancy in 6 mares. The effect was observed in 3-5 min after the i.m. injection and it lasted for 50-70 min. 20 and 40 micrograms/kg b.w. doses of detomidine decreased the myometrial electrical activity, whereas 60 micrograms/kg dose did not have any effect on the activity. The results suggested that 20, 40 and 60 micrograms/kg b.w. doses of detomidine can be administered to mares during the last trimester of pregnancy without the risk of abortion induced by increased uterine electrical...
Alonso MA, Silva LA, Affonso FJ, Lemes KM, Celeghini ECC, Lançoni R, Carvalho HF, de Arruda RP.Establishment of pregnancy after embryo transfer is the ultimate goal of an embryo transfer program and increasing pregnancy rates and reducing pregnancy loss are mandatory. The utilization of treatments to improve conception rates in recipient mares has been the focus of several research groups over the last years and the results are controversial. Some studies using human chorionic gonadotrophin (hCG) found promising results. Our hypothesis was that hCG administration would cause an additional stimulation on luteal function, uterine and luteal vascularization and progesterone concentration, ...
Lowe JE, Foote RH, Baldwin BH, Hillman RB, Kallfelz FA.Three Quarter-horse mares were thyroidectomized at about 1.5 years of age. Three similar intact mares served as controls. The study continued through two breeding seasons. The thyroidectomized mares were lethargic, rear limbs were oedematous and hair coats were coarse. They displayed a tranquil oestrous behaviour when exposed to a stallion and were only mildly antagonistic when not in oestrus. Length of oestrous cycles varied but most often they were 19-24 days long. Duration of oestrus (mean +/- s.e.m.) for the control and thyroidectomized mares was 12.9 +/- 2.9 and 11.7 +/- 2.2 days respecti...
Bracher V, Mathias S, Allen WR.Placentation between 80 and 220 days of gestation was studied by measurement of fetal dimensions and gross, light and transmission and scanning electron microscopic examinations of the allantochorion and endometrium from 4 fertile mares with no, or very mild, endometrial histopathology and 6 subfertile Thoroughbred mares suffering varying degrees of age-related chronic degenerative endometritis (endometrosis). Spontaneously occurring twin gestation was observed in 3 animals. Several of the subfertile mares had endometrial cysts which showed 2 distinct features during pregnancy: those located n...
Robles M, Gautier C, Mendoza L, Peugnet P, Dubois C, Dahirel M, Lejeune JP, Caudron I, Guenon I, Camous S, Tarrade A, Wimel L, Serteyn D....Pregnant mares and post-weaning foals are often fed concentrates rich in soluble carbohydrates, together with forage. Recent studies suggest that the use of concentrates is linked to alterations of metabolism and the development of osteochondrosis in foals. The aim of this study was to determine if broodmare diet during gestation affects metabolism, osteoarticular status and growth of yearlings overfed from 20 to 24 months of age and/or sexual maturity in prepubertal colts. Methods: Twenty-four saddlebred mares were fed forage only (n = 12, group F) or cracked barley and forage (n = 12, group ...
Gilbert RO, Marlow CH.Records of 1,009 pregnancies in 574 foaling, barren and maiden Thoroughbred mares on a single stud farm, over a period of 12 years were examined. The farm is situated in the eastern Cape Province of South Africa, at an elevation of 1,800 m, and in an area of climatic extremes. Records of 604 pregnancies in 249 foaling Thoroughbred mares were examined. For these purposes, those pregnancies in which a mare conceived in the same breeding season during which she had foaled were considered as pregnancies in foaling mares. Pregnancy was confirmed by rectal palpation by a single experienced practitio...
Beythien E, Aurich C, Wulf M, Aurich J.Seasonal changes in metabolic rate have been shown in horses and we hypothesized that this leads to the birth of smaller foals early in the year. Mares and their foals were assigned to three groups by day of foaling within the year (e.g. 1 January = day 1): Group 1 (n = 10) day 40-65, group 2 (n = 8) day 67-92, group 3 (n = 9) day 94-121. Groups did not differ with regard to parity. In foals, height at withers and body weight were determined on days 1-5 and weekly until 12 weeks of age. Chest circumference, distances fetlock to carpus, carpus to elbow, poll to nose and crown-rump lengt...
Donatsch L, Friker B, Sieme H, Kaeser R, Burger D.A potential source of fertility loss in mares is oviductal dysfunction, potentially caused by masses or debris in the lumen, that may prevent either sperm from reaching the fertilization site or the embryo from reaching the uterus. Recently a novel therapeutic method leading to increased pregnancy results was described by infusing misoprostol, a synthetic prostaglandin E, in the uterus of mares with unexplained fertility problems. In this study, we aimed, after examining the compatibility of misoprostol with semen, to evaluate the pregnancy rate after routine preovulatory deep uterine horn app...
Barrier Battut I, Kempfer A, Becker J, Lebailly L, Camugli S, Chevrier L.Several laboratories routinely use flow cytometry to evaluate stallion semen quality. However, objective and practical tools for the on-field interpretation of data concerning fertilizing potential are scarce. A panel of nine tests, evaluating a large number of compartments or functions of the spermatozoa: motility, morphology, viability, mitochondrial activity, oxidation level, acrosome integrity, DNA integrity, "organization" of the plasma membrane, and hypoosmotic resistance, was applied to a population of 43 stallions, 33 of which showing widely differing fertilities (19%-84% pregnancy rat...
Pascoe DR, Pascoe RR, Hughes JP, Stabenfeldt GH, Kindahl H.One hundred mares carrying twin conceptuses between gestation days (GD) 12 and 30 were assigned to 4 groups. Group-1 mares (n = 20) were given a placebo (sterile saline solution, IV, and sesame oil, IM). Group-2 mares (n = 32) were given a single dose of progesterone (625 mg, IM) in sesame oil. Group-3 mares (n = 28) were given multiple progesterone treatments (625 mg, IM) at 6-day intervals until GD 42. Group-4 mares (n = 20) were given a single treatment of flunixin meglumine (500 mg, IV) and progesterone (625 mg, IM). Each group was further assigned to equal subgroups A and B according to t...
Urquieta B, Durán MC, Coloma I, Parraguez VH.Our aim was to compare Corpus luteum (CL) development and blood plasma concentration of progesterone ([P4]) in thoroughbred mares after spontaneous ( Methods: C) or human chorionic gonadotrophin (hCG)-induced ovulation. Lactating mares (C=12; hCG=21) were daily teased and mated during second oestrus post-partum. Treated mares received 2500 IU hCG i.v. at first day of behavioural oestrus when dominant follicular size was >35, or=45 mm. Dominant follicle before ovulation, CL and gestational sac were measured by ultrasound and [P4] by radioimmunoassay (RIA). Blood sampling and ultrasound CL ex...
Güvenc K, Reilas T, Katila T.Pregnancy rates after frozen semen inseminations (AI), particularly in older and problem mares, are lower than after fresh semen AI. Uterine contractility and the inflammatory reaction after frozen semen insemination were studied in two groups of mares: the abnormal group comprised of 6 old barren mares categorized in biopsy category IIB or III, and the control group including 6 reproductively normal young maiden mares in biopsy category I or IIA. All 12 mares were inseminated in the first cycle with 2 mL of phosphate-buffered saline (PBS) and in their second cycle with 2 mL of frozen semen co...
Pazinato FM, Curcio BDR, Varela Junior AS, Corcini CD, Wendt CG, Moreira F, Schmit RA, Nogueira CEW.Placental tissues from humans, rodents, and farm animal contain leptin and its receptor. Expression of leptin has already been described in horses, although there is no description about immunolocalization of leptin and its receptor. The aim of the present study was to investigate the presence and distribution of leptin and ObR-b in the equine placenta at term by immunofluorescence staining, and the changes on plasma leptin concentrations during late gestation. The present study involved eight Criollo-type mares carrying healthy pregnancies. Blood samples were collected during the third trimes...
Antczak DF.A new polymorphic locus of the horse which has several unusual properties is described. The suggested name for the locus is ELY-2. The gene product of one allele at this locus, designated ELY-2.1, has been identified with antisera raised as a result of pregnancy. Antibody to ELY-2.1 was first detected on day 55 after conception in the serum of a mare in first pregnancy. This early onset of antibody is similar to that seen for antibody to ELA antigens, and suggests that the source of the antigenic stimulus may be the tissue of the equine endometrial cups. The antisera identifying ELY-2.1 are cy...
Bowers S, Gandy S, Anderson B, Ryan P, Willard S.The objective of this study was to investigate use of digital infrared thermal imaging (DITI) to determine whether surface temperature gradient differences exist between pregnant and nonpregnant mares as a noncontact method to determine pregnancy status. On the day measurements were collected, each pregnant mare (n=10; beginning at 292.4+/-1.4 d of gestation) was paired with a nonpregnant mare (n=17). Ambient temperature, DITI measurements (left and right flank, wither temperatures [i.e., animal surface control] and background temperature), and rectal temperatures were obtained every 7 d for 5...
Woods GL, Ginther OJ.The ability of a pituitary extract to induce ovulation and the effect of multiple ovulations on pregnancy rate and incidence of multiple fetuses were studied in seasonally anovulatory mares. The extract induced ovulation in 95% of mares having a greater than or equal to 25 mm follicle at the onset of treatment and in 64% the ovulations were multiple. The extract was less effective when the largest initial follicle was less than 25 mm. Approximately 50% of the treated mares that ovulated did not become pregnant or enter prolonged dioestrus before returning to an anovulatory condition. In treate...
Scherzer J, Davis C, Hurley DJ.The major difficulty in providing the benefits of embryo cryopreservation for equine agriculture is the mismatch between the optimal embryo age for collection from the mare (7-8 days after ovulation was detected) and the optimal age for freezing under current methods (6.5 days after ovulation). To overcome this limitation, we tested a method to enhance penetration of cryopreservative across the capsule and trophoblast of day 7 and 8 embryos combined with rapid freezing by vitrification. Six small embryos (<300 μm in diameter) were collected on day 6-7 after ovulation and twelve larger embryos...
Zhao Q, Tao C, Pan J, Wei Q, Zhu Z, Wang L, Liu M, Huang J, Yu F, Chen X, Zhang L, Li J.Fixed-time artificial insemination (FTAI) technology uses exogenous reproductive hormones to regulate the sexual cycle and ovulation of sows without oestrus identification, which improves the sow breeding utilisation rate, reduces the number of non-productive days, and elevates the efficiency of pig farm management. In this study, we aimed to optimise FTAI procedures. Healthy 190-day-old and about 90 kg Large White × Landrace crossing breed replacement gilts (n = 166) which were of unknown reproductive status were randomly selected and divided into three groups: a control group (n = 62...
Huber D, Amsler E, Vidondo B, Kaeser R, Wespi B, Sieme H, Burger D.There exist differences in the reproductive behavior of stallions and mares under free-running and domestic in-hand breeding conditions. Contrary to artificial insemination programs, a stallion mates a mare multiple times per estrus under natural conditions. The objective of this study was to determine if multiple periovulatory artificial inseminations (MI), four times in two different time intervals instead of two, would result in increased pregnancy outcome or higher incidences of breeding induced endometritis. Methods: Eighty-two estrous mares were allocated randomly to one of three experim...
Consuegra C, Crespo F, Dorado J, Diaz-Jimenez M, Pereira B, Sánchez-Calabuig MJ, Beltrán-Breña P, Pérez-Cerezales S, Rizos D, Hidalgo M.The aim of this study was to evaluate the fertilizing capacity of frozen or vitrified stallion sperm after assessing different warming procedures. In Experiment 1, different warming procedures were compared after sperm vitrification: immersion in extender at 43 °C (C), or in a water bath at 37 °C/30 s (W37), 43 °C/10 s (W43) or 60 °C/5 s (W60). With the W60 treatment, there were greater values (P < 0.05) for VCL (83.93 ± 3.6 μm/s) and ALH (3.00 ± 0.2 μm) than freezing and with the C group, and greater values (P < 0.001) for PM (35.33 ± 2.5 %) than with the W43 treatment. In Experiment...
