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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 equine coital exanthema on the fertility of mares covered by stallions exhibiting the clinical disease. The effect on the fertility of mares during two outbreaks of equine coital exanthema have been described. Conception was not prevented, nor was pregnancy terminated in mares showing active lesions of coital exanthema. Normal pregnancy rates occurred in mares served during active infection of the stallions. Origin of the disease was not determined.
A cytogenetical study of prenatal loss in the mare. The objective of this study was to investigate an hypothesis that chromosome anomalies are an important cause of prenatal loss in the mare. An attempt was made to analyse, cytogenetically, a series of 26 equine abortuses. Cell cultures were prepared from a range of tissues, but failed to grow, and chromosome analysis was therefore not possible for any of these specimens. Consequently, a study was made of the metaphase chromosomes prepared from 22 equine embryos after their surgical removal from mares' uteri. The karyotypes prepared for each specimen were normal. The current findings are discus...
Studies on the chromosomes and sex chromatin in the horse. This study provides accumulated data to assist the definition of karyotypes from normal and infertile horses. The normal karyotype of the horse (2n = 64) was characterized following Giemsa staining and C- banding, and 23% aneuploidy was found among chromosome counts of cells prepared from 44 clinically normal horses and 24 equine embryos. These expected variations in chromosome counts are especially important in the evaluation of potential mosaicism. Centromere staining was shown to be a valuable aid for the identification of specific chromosomes, in particular the sex chromosomes. Sex chromat...
The use of endometrial biopsy in the infertile mare. The results of a study on endometrial biopsies obtained from 700 infertile mares are reported. Infiltrative endometritis was present in 51% consisting of a combination of an acute and chronic cellular response in 6%, mild chronic infiltrations in 35% and moderate to severe chronic infiltrations in 10%. Demonstrable endometrial fibrosis was found in 88% of the mares with the majority having mild (51%) or moderate (35%) changes. The age of the mares and the average number of years barren gradually increased with the severity of endometrial fibrosis, as did the combined incidence of fetal loss (e...
Physico-chemical properties of pregnant mare serum gonadotropin. Pregnant mare serum gonadotropin exhibits a dissociation at acid pH as shown by the drop of s20,w values from 3.52 S at pH 8.1 to 2.52 S at pH 2.0. The dissociation is accompanied by an absorbance change with a maximum at 287 nm and a parallel loss of both follicle-stimulating hormone (FSH) and luteinizing hormone (LH) activities as followed by radioreceptor assays. The apparent pKa of the acid transition is 3.45 with an extremely slow and temperature-dependent rate at pH 2.0 (1.8 . 10(-4) s-1 at 37 degrees C). By gel filtration the molecular weight of the active hormone is estimated to be 45 ...
Torsion of the spermatic cord in a horse. A 360-degree torsion of the left spermatic cord was diagnosed in a 2 1/2-year-old Quarter Horse colt. Clinical signs included abdominal discomfort, with slight elevations in heart and respiratory rates. The scrotum on the left side was moist and edematous. The left testicle was enlarged, firm, and retracted slightly toward the abdominal cavity. The colt resented palpation of the testicle. On rectal palpation, the left vaginal ring and the structures passing through the ring were edematous and painful to pressure. Surgical correction was achieved by emasculation. The tail of the epididymis and ...
A complication of cryptorchid castration in three horses. During an 8-month period, 3 horses were examined because of incomplete cryptorchid castration. Each horse had had surgery to remove 1 retained testis. In each case, the attending veterinarian believed castration had been adequately completed. History, rectal examination findings, and in 2 cases, high serum testosterone concentration were factors that led to the decision to do exploratory surgery on each horse. In each case, initial surgery had resulted in surgical removal of the tail of the epididymis, which was mistaken for testicular tissue.
Relationship between early pregnancy site in consecutive gestations in mares. The records of 200 pairs of consecutive pregnancies in mares showed that in 82 per cent of cases the second pregnancy was initially established in the opposite uterine horn to that of the first, irrespective of the parturition to conception interval. This relationship also occurred when the first pregnancy ended in abortion after 140 days but not if it terminated before this time.
Culture of horse oocytes in vitro. Oocytes were removed from follicles 5-30 mm in diameter. The germinal vesicle was present in 69.6% (23/33) of the oocytes at the start of culture, but after 20-24 and 40 h 70.5% (12/17) and 68.2% (43/63) of the oocytes were in metaphase I and metaphase II with first polar body extruded, respectively.
[Localization of beta-n-acetylhexosaminidase in stallion epididymis (author’s transl)]. The localization of beta-N-acetylhexosaminidase activity in 6 different segments of the epididymis was investigated in 8 stallions using biochemical and histochemical methods. The highest enzyme activity was found in segment D while the other segments displayed a much weaker reaction There was no or only low enzyme activity present in the epididymal fluid of the proximal 3 segments, whereas it was high in the distal 3 segments. The biological function of beta-N-acetylhexosaminidase in the epididymis is discussed briefly.
Coat color and gestation length in thoroughbred mares. Average gestation periods for bay, chestnut, dark bay, gray, and black Thoroughbred mares were compared. A total of 1359 gestation periods were used. A linear model including factors for age of mare, sex of foal, month and year of breeding, and sire effects was used in the analysis. Dam and sire coat-color combinations were also investigated in a similar manner. No significant differences in gestation length could be attributed to coat color of the mare of to dam and sire coat-color combinations. Heritability of gestation length was estimated to be 0.38. The results of this study strongly sugg...
Variations in the properties of equine chorionic gonadotropin. The objectives of this paper are to review the chemical and biological properties of equine chorionic gonadotropin (eCG, PMSG) isolated from the serum. Comparisons are made with eCG isolated from endometrial cups, trophoblast cell culture medium, and low titer serum. The results show that eCG can vary, depending on the source, in both chemical and biological (LH and FSH activity) properties.
[Inactivated vaccines against rhinopneumonitis in horses]. Attempts were made to produce inactivated vaccines against horse Herpes virus 1, using various inactivating agents and adjuvants, Best results were obtained with vaccine No 3 (glutaraldehide inactivator and "CTC" adjuvant). Used were two strains of the virus (St. Karaja and Varna). isolated in this country in cell cultures of a sucking pig kidney. Vaccine No 3 showed good immunogenic properties. Its application resulted in the full cease of abortions and respiratory diseases on the base of infection with the horse Herpes virus 1. The vaccination protects newborn colts from rhinopneumonitis if ...
In vivo metabolism of [3H]equilin in the pregnant mare. [3H]Equilin [3H-labeled 3-hydroxy-1,3,5(10), 7-estratetraen-17-one] was administered iv to a pregnant mare in the 10th month of gestation. Maternal urine was collected for 3 days, and blood samples were taken 35 min and 3, 6, 12, and 24 h after the injection. The half-life of the disappearance of radioactivity from the blood was approximately 2.5 h. Over 90% of the administered dose was excreted in the first 24 h. The urine was extracted, hydrolyzed, and fractionated. The bulk of the radioactive material (75%) was present in the phenolic sulfate fraction from which radiochemically pure equilin...
