Omneity® Pellets
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Topic:Reproduction
Reproduction in horses encompasses the biological processes and mechanisms involved in the breeding and development of equine offspring. This includes the study of reproductive anatomy, physiology, and endocrinology in both mares and stallions. Key areas of interest include the estrous cycle, ovulation, conception, gestation, and parturition. Researchers also examine factors influencing fertility, reproductive technologies such as artificial insemination and embryo transfer, and management practices that impact reproductive success. This page compiles peer-reviewed research studies and scholarly articles that explore the physiological, genetic, and environmental aspects of equine reproduction.
Assignment of foal paternity when a mare is bred to two stallions. Accuracy of assigning foal paternity to the second serving stallion for foals whose dams had been bred to two stallions within an interval of 1 to 45 days was investigated using breeding dates from 108 equine paternity cases solved by blood typing. One hundred two of the foals were sired by the second stallion but six foals (5.5%) were excluded as being by the second sires. Thus, breeding dates are not reliable as a sole source of information to assign equine paternity accurately.
Equine congenital defects. In a 13-year survey of equine congenital defects that resulted in death or required euthanasia in central Kentucky, necropsies were performed on 608 deformed fetuses or newborn foals. The following congenital anomalies were observed: contracted foal syndrome (33.2%), miscellaneous limb contraction (20%), multiple defects (5.3%), microphthalmia (4.6%), craniofacial malformations (4.3%), cleft palate (4.0%), heart defects (3.5%), umbilical defects (3.5%), and hydrocephalus (3.0%). Eleven less frequently occurring anomalies constituted the balance of the congenital defects in fetuses and newborn ...
Uterine involution in mares treated with progesterone and estradiol-17 beta. Bacteriology, histology, and scanning electron microscopy were used to evaluate uterine involution in 27 mares treated with daily injections of 150 mg of progesterone and 10 mg of estradiol-17 beta, commencing within 18 hours of parturition. These findings were compared with those for 24 untreated mares at postpartum day 10 or 11. The treatment resulted in significantly (P less than 0.05) greater uterine gland proliferation. Gland density was significantly (P less than 0.05) greater in mares treated for 6 to 10 days than in those treated 2 to 5 days. The proportion of ciliated cells to secreto...
Surgical management of perineal lacerations and rectovestibular fistulae in the mare: a retrospective study of 47 cases. The case records of 47 mares with third-degree perineal lacerations or rectovestibular fistulae were examined to evaluate their fertility following surgical repair. Of 32 mares bred, 24 became pregnant, suggesting that surgical repair is indicated in any mare with sufficient genetic potential. Perineal trauma after surgical repair was recorded in 3 of 20 mares at subsequent parturition.
Activity of delta(5)3beta-hydroxysteroid dehydrogenase and steroid hormones content in early preimplantation horse embryos. The activity of delta (5)3 beta-hydroxysteroid dehydrogenase was examined histochemically in 6 to 10 days aged horse blastocysts. A positive reaction was noted in the blastomeres of all embryos incubated in medium with substrate. Measurable amounts of progesterone, androgens and estrogens were found in blastocysts on day 8th. The presence of enzyme and hormones suggests that steroid hormone production takes place in very early preimplantation horse embryos.
Characteristics of Mycoplasma strains isolated from stallion semen. Eleven mycoplasma strains were isolated from the semen of 24 stallions. Eight of these strains were identified as Mycoplasma equigenitalium. Three strains which hydrolized arginine could not be identified. The growth inhibition test with immune sera against M. arginini and M. equirhinis was negative. Antibiotic sensitivity test showed that all strains were sensitive to four antibiotic of tetracycline group (oxytetracyclin, minocycline, transcycline and vibramycin). Lincomycin and gentamycin appeared to be the most active against all the strains. Comparative analysis of routine semen examinatio...
Immunohistological studies of the local immune system in the reproductive tract of the mare. The immunoperoxidase technique was adapted for the identification of free immunoglobulin and immunoglobulin producing cells in equine tissues. Staining specific for free IgG, IgA and IgM was detected at all levels of the reproductive tract, and secretory component staining was present in the uterine epithelium but not in the oviduct, cervix or vagina. Immunoglobulin producing cells were present at all levels of the tract, with IgG and IgA cells at equivalent concentrations, but with fewer IgM cells. There was no cyclical trend in free immunoglobulin staining, or plasma cell numbers. IgG and Ig...
Seasonal changes in blood serum protein fractions and in activity of AspAT and AlAT in Arabian brood mares and their foals. In 34 pure breed Arabian horses divided into four groups (Gr. I--10 pregnant mares, Gr. II--7 barren mares, Gr. III--10 foals born in 1981, Gr. IV--7 foals born in 1982) seasonal changes in total blood serum protein, its electrophoretic fractions and the activity of AspAT and AlAT were studied. Seasonal cyclicity was found in all groups in the amount of total serum proteins, and alpha 2- and beta 1-globulin fractions. Cyclicity was found in the level of albumin and activity of AspAT in three groups, not Gr. II, and in gamma-globulin, not Gr. IV. beta 2-globulin and AlAT cyclicity was found in ...
Radioimmunoassay of 19 nor testosterone. Evidence of its secretion by the testis of the stallion. Antiserum has been raised in rabbits treated with a 19 nor testosterone-hemisuccinate-bovine-serum-albumin conjugate and used for the development of a specific RIA of plasma 19 nor testosterone. Plasma samples are drawn from testicular and jugular veins of stallions during castration under general anesthesia. Results demonstrate a testicular secretion of 19 nor testosterone and a stress inhibition of this secretion correlatively with stress inhibition of testosterone secretion.
Physiological peripubertal activation of the ovary is not reproduced by pregnant mare serum gonadotropin (PMSG) administration. During the days preceding the first ovulation the ovary of the rat exhibits a remarkable increase in estradiol (E2) and progesterone (P) release in response to gonadotropins. No such increase is observed in the case of androgens (A, testosterone + dihydrotestosterone). The present experiments were undertaken to examine the possibility of reproducing these developmental events by stimulating the ovary with a gonadotropin that has substantial FSH-like activity. In vivo administration of pregnant mare serum gonadotropin (PMSG) to juvenile 29-day-old rats greatly increased the in vitro E2 and A re...
[Direct and indirect methods of the diagnosis of pregnancy in mares]. This review article deals with a critical comparison between the direct clinical diagnosis for the pregnancy of the mare (rectal and in some cases also vaginal exploration) and indirect methods. Both methods are discussed whether they can be seen as a mutual completion or are suitable for their own. The indirect methods for the pregnancy diagnosis include the hormone-analytic tests as progesterone concentration in serum or milk, the biological and immunological measurements for PMSG in the serum, finally the biological and chemical methods for estrogen contents in the urine of the mare. Furthe...
Effect of age of equine embryos and method of transfer on pregnancy rate. A 2 X 2 cross-classified experiment was conducted to investigate the effect of age of equine embryo (7 vs 8 d postovulation) and method of transfer (surgical vs nonsurgical) on pregnancy rates at 50 d of gestation. Embryos were recovered 7 or 8 d postovulation using a Foley catheter and 3 liters of modified Dulbecco's phosphate-buffered saline (PBS). Upon identification, the embryos were placed in millipore-filtered PBS containing 20% heat-inactivated steer serum and maintained at room temperature until transferred. At the time of recovery, embryos were randomly assigned to be transferred eith...
Experimental infection of mares with Haemophilus equigenitalis. Inoculation of Haemophilus equigenitalis into the uterus of 7 mares caused a disease clinically indistinguishable from contagious equine metritis. The duration of clinical signs varied from 4 to 11 days. The causative organism persisted for a relatively short time (2 to 10 weeks) in 5 mares, but in 2 others it established a carrier status and persisted until they were killed 6 and 10 months after infection. H. equigenitalis was recovered from the vestibule of the vagina and from a combined swab of the clitoral fossa and sinuses throughout the course of the infection. In some mares there were e...
The effect of estradiol and progesterone on the sexual behavior of ovariectomized mares. Daily treatment (5 days) with estradiol resulted in increased levels (p less than 0.05) of proceptive behavior in ovariectomized as compared to control mares (N = 8 per treatment) within 4 hr of injection and for the 4 subsequent days. Ejaculations occurred more often (p less than 0.05) in estrogen-treated mares on days 2-5, but the number of precopulatory investigations by the stallions was not altered. Progesterone treatment resulted in an absence of sexual behavior except in one mare on Day 1. Control mares exhibited varying levels of sexual interest. The concurrent administration of estrad...
The effects of EDTA-Tris infusion on the equine endometrium. Four groups of five pony mares each were used to determine if the intrauterine infusion of EDTA-Tris solution caused adverse effects on the endometrium. The uteri of mares were infused with either saline or EDTA-Tris solution or biopsied or sham-biopsied without infusion. Acute endometritis developed in one (20%) to three (60%) mares in each group during the seven days following treatment, but there were no differences (P > 0.05) in the incidence of endometritis among the groups. Endometrial fibrosis was not evident in biopsies taken on days 14, 30 and 60 following infusion of saline or EDT...
Serial investigations of early pregnancy in pony mares using real time ultrasound scanning. The uteri of 13 pony mares were examined daily by ultrasound during the first two months of gestation. The conceptus was first identified between 12 and 16 days after ovulation and the embryo was seen on the ventral surface of the conceptus after Day 21. The foetal heart could be visualised after Day 22 and spontaneous movement of the foetus occurred after Day 39. No consistent pattern was seen in the development of the foetal membranes, although attachment of the umbilical cord to the allantochorion was always on the dorsal aspect of the conceptus. Daily measurements were made of the diameter...
Quantitation of the immunoglobulins in reproductive tract secretions of the mare. IgG, IgA, IgM and albumin concentrations were measured in serum, follicular fluid and oviductal, uterine and intestinal secretions of the horse. Follicular protein concentrations were found to be dependent on serum concentration and molecular size. Of the immunoglobulins only IgG was detectable in oviductal secretions, but IgG:albumin ratios did not differ significantly from those in serum. IgG, IgA and IgM were measured in uterine secretions, with IgG predominant. Serum transudation into uterine secretions was minimal. In intestinal secretions, IgA levels were slightly higher than IgG, with a...
Continuous cultivation of equine lymphocytes: evidence for occasional T cell-like maturation events in horses with hereditary severe combined immunodeficiency. Peripheral blood mononuclear cells (PBMC) from 14 foals with hereditary severe combined immunodeficiency (SCID) were studied to determine the extent of lymphocyte differentiation that occurs in this disorder. PBMC from all 14 horses had the morphologic characteristics of large granular lymphocytes (LGL). Cells from only one of 14 horses were responsive to phytolectin stimulation in a standard blastogenesis assay; however, PBMC from all 14 horses proliferated in continuous culture in the presence of partially purified interleukin 2. Furthermore, there were differences in the growth patterns of ...
Usefulness of lymphocyte typing to exclude incorrectly assigned paternity in horses. Lymphocyte typing can be used to detect incorrectly identified parentage of horses. Efficacies of lymphocyte typing to solve paternity questions were calculated using gene frequency estimates of equine lymphocyte antigen (ELA) markers for Thoroughbreds and Standardbreds. Probabilities that ELA typing will detect an incorrectly assigned sire were 68.7% in Thoroughbreds, 67.9% in pacing Standardbreds, and 62.0% in trotting Standardbreds. These calculations demonstrate that ELA typing is among the most efficacious genetic systems for solving paternity questions in horses. Likewise, it could also ...
Serum testosterone levels in young normal horses. Serum testosterone levels were measured in normal young male horses (29 to 34 weeks old). No differences were found between gelded and intact males. The values for all the horses were low. On the basis of their testosterone levels, all the horses were prepubertal.
