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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.
The effect of benzo(a)pyrene on fertility, primordial oocyte number, and ovarian response to pregnant mare’s serum gonadotropin. The polycyclic aromatic hydrocarbon (PAH) benzo(a)pyrene (BP) reduced the fertility of DBA/2N mice in a dose-dependent fashion. Control mice produced offspring at a rate of 0.91 pups/mouse per week. Treatment with BP at doses of 10, 100, 200, and 500 mg/kg decreased offspring production rates to 0.61, 0.20, zero and zero pups/mouse per week, respectively. BP also destroyed primordial oocytes in similarly treated mice. Treatment with BP at doses of 10, 50, 100, and 500 mg/kg destroyed 20%, 58%, 88%, and 100%, respectively, of the primordial oocytes in DBA/2N mouse ovaries. Dose-response curves ...
Estrus, ovulation, and serum hormones in mares given prostaglandin F2 alpha, estradiol, and gonadotropin-releasing hormone. A gonadotropin-releasing hormone (GnRH) was injected in mares given prostaglandin F2 alpha (PGF2 alpha) to induce luteolysis in an attempt to sunchronize ovulation. Pretreatment with estradiol-17 beta (E2-17 beta) was used to determine whether or not estradiol would enhance the release of luteinizing hormone (LH) after treatment with GnRH. Twelve mares were used in a balanced Latin square crossover design. Mares were injected with PGF2 alpha, treatment A; PGF2 alpha mgnRH, treatment B; or PGF2 alpha me2-17 beta mgnRH, treatment C. The interval +/- SEM from PGF2 alpha injection to estrus was 3....
[Purposeful (blood-)horse breeding (author’s transl)]. Horse-breeding in the Netherlands is briefly reviewed. Particular attention is paid to the number of foals of various breeds. Some effects of inbreeding in Friesian horses are discussed. As regards methods selection, attention is mainly paid to saddle horses. The role of veterinarians (from the point of view of selection for soundness) is described. Selection is based on the results of studies in the Faculty of Veterinary Medicine in Utrecht. A number of these results are reviewed.
Induction of estrus and ovulation by endometrial biopsy in mares with prolonged diestrus. Luteolysis, estrus, and ovulation were induced by endometrial biopsy during three periods of prolonged diestrus in two mares. Serum progesterone concentrations decreased to less than 1 ng/ml within 48 hours after biopsy. Mares were in estrus within 3 days after endometrial biopsy. It was concluded that endometrial biopsy may induce regression of the persistent corpus luteum by stimulating the release of an endogenous uterine luteolysin (prostaglandin).
Evidence of the origin of the gelatinous masses in the oviducts of mares. The gelatinous masses known to occur in the mare oviduct were examined by light and scanning electron microscopy. Many (44%) of the masses which occurred in 16 of the 24 oviducts studied were connected with the mucosa of the ampulla near the ampullary-isthmic junction. The masses consisted of lobules of fine fibres probably derived from the fibrous connective tissue of the lamina propria in the oviductal mucosa.
Changes in concentrations of circulating gonadotropins following administration of equine follicular fluid to ovariectomized mares. The effects of administration of equine follicular fluid (FF) on gonadotropin concentrations in the ovariectomized (OVX) mare were examined. The FF was obtained by aspiration of follicles in ovaries obtained during the summer at a slaughterhouse. Systemic administration of whole equine FF to OVX mares resulted in significant decreases in circulating concentrations of FSH (26.0–74.0% of the pretreatment concentrations depending on dosage). Treatment with FF from which steroids had been removed tended (P0.10) on FSH. Treatment with whole FF initially decreased and then increased the concentrat...
A cytogenetic study of the Caspian pony. The group of Caspian ponies studied contained some animals with 65 chromosomes and others with 64 chromosomes. The morphology and G-banding pattern of the chromosomes resembled those of Equus caballus and E. przewalskii. The karyogram of animals with 65 chromosomes was identical to that of the cross between E. caballus and E. przewalskii. It is suggested that the Caspian pony is the product of natural hybridization between E. caballus and E. prezwalskii. Low reproductive effeciency of the Caspian pony is suggested as the cause of decline in the population of these animals.
The location of eggs retained in the oviducts of mares. The oviducts of 24 mares were examined to determine the site of retention of unfertilized eggs. The ampullary-isthmic junction regions of 42 of the 48 oviducts were serially sectioned and examined histologically. The remaining parts of the oviducts were flushed and the flushings searched microscopically. Of 45 eggs located, 40 were in the sectioned segments of 24 oviducts and only 5 were in the flushings. All but one of the sectioned segments contained prominent masses of material obstructing the lumen, but these were apparently not the direct cause of egg retention since eggs were found on bo...
A study of Klebsiella pneumoniae infection in the uterus of the mare. Two experiments incorporating 13 mares were conducted for the purpose of producing and monitoring intrauterine infection with Klebsiella pneumoniae. In the pilot study, the infection was produced with strains of K pneumoniae type 68 and type 10 isolated from the genital tract of stallions with a history of breeding problems. In the principal study, K pneumoniae type 68 was used to produce the infection. Tampons and guarded culture swabs were used to obtain uterine samples in the pilot study. In comparing the efficacies of isolation of K pneumoniae with the tampons and isolation with standard g...
Evaluation of uterine tube function in pony mares. Two experimental procedures were investigated in order to assess their usefulness in diagnosing occlusion of the equine uterine tube. The starch grain test, which involves the injection of a starch suspension onto the ovary and the subsequent recovery of starch from the cervix, proved to be safe and reliable. Each tube could be investigated separately. It was found that when starch was injected onto the ovulating ovary on the day of ovulation, there was a delay of four to seven days before starch was recovered from the cervix. The phenolsulphonphthalein (PSP) test, which involves the depositio...
Bacteria isolated from uterine washings from mares in the Sudan. Uterine washes collected from 200 barren mares were examined at the Khartoum veterinary clinic during the period May 1977 to May 1978. A variety of bacteria was isolated from 77 per cent of the mares investigated. Thirty mares were treated by parenteral injection and intrauterine infusion of the appropriate antibiotics. Twenty-one of these mares conceived, of which 17 delivered normal foals and 4 had early embryonic deaths.
A survey of early pregnancy losses in West German thoroughbred mares. Embryonic resorption is reported as the main reason for early pregnancy losses in the West German Thoroughbred mare. An analysis of breeding records for the last 11 years showed a resorption rat of 8.4 per cent. Evidence was obtained that these early embryonic losses were associated with too early conception after foaling and with the state of lactation.
Effects of restrictive suckling on postpartum reproductive performance in mares. Quarter Horse mares (n = 30) and their foals were used in a 2-year study. Objectives of the study were (i) to determine the effects of a treatment regimen, which permitted nursing for four 1-hour periods each day, on the postpartum reproductive performance of the dams, and (ii) to assess the effects of this procedure on the growth and development of foals. Mares in the restricted suckling treatment group showed estrus and ovulated sooner (P less than 0.01) after parturition than did control mares during the first year of the study, but not during the second year. Plasma progesterone concentrat...
