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Topic:Horse Breeds
Horse breeds represent the diverse genetic and phenotypic variations found within the species Equus ferus caballus. These breeds are categorized based on characteristics such as size, conformation, coat color, and temperament, which have been selectively bred over centuries to fulfill specific roles and functions. Common classifications of horse breeds include light horses, draft horses, and ponies, each serving different purposes ranging from riding and racing to work and companionship. This page aggregates peer-reviewed research studies and scholarly articles that explore the genetics, history, and functional attributes of various horse breeds, as well as their impact on equine management and breeding practices.
Insemination results with slow-cooled stallion semen stored for approximately 40 hours. Semen from 3 stallions was extended using 2 methods (Kenney extender and a modified Kenney extender), slowly cooled, and stored for 41 +/- 6 (s.d.) h before insemination. An insemination dose (40 ml) contained 1.5-2 billion spermatozoa. In the experiment, 26 mares were inseminated in 30 cycles. The pregnancy rate per cycle obtained with sperm stored in the Kenney extender was 87% (n = 15). When the semen was extended with the modified extender, centrifuged and stored, the pregnancy rate was 60% (n = 15). Inseminations were done every other day until ovulation was detected. If a mare ovulated m...
Fine structure of equine oocytes matured in vitro for 15 hours. Transmission electron microscopy (TEM) was used to evaluate the fine structure of equine oocytes cultured in vitro. Oocytes obtained by follicular aspiration were cultured for either zero or 15 hr. After treatment oocytes were processed either by light microscopy (nuclear evaluation) or TEM (cytoplasmic evaluation). Those oocytes cultured for 15 hr were incubated in modified TCM 199 with 15% (v/v) mare serum (day of ovulation) at 39 +/- 0.2 degree C. Evaluation using TEM revealed that cortical granules were present in all oocytes. However, zero-time oocytes contained few cortical granules, and...
Post-thaw motility and longevity of motility of imipramine-induced ejaculates of pony stallions. Imipramine-induced ex copula ejaculates (11) and fractionated in copula ejaculates were collected from each of 5 pony stallions for freezing in 5-ml straws (6), using a modified Kenney glucose skim-milk extender (2). Initial post-thaw total and progressive motilities and daily post-thaw total and progressive motilities, as well as the number of days to reach 0 progressively motile spermatozoa, were also similar for the 2 methods of collection. The percentage of morphologically normal spermatozoa both before freezing and after thawing were also similar for in copula and ex copula ejaculates. Co...
Preservation of ejaculated and epididymal stallion spermatozoa by cooling and freezing. The suitability of ejaculated and epididymal stallion spermatozoa for cooled storage (5 degrees C) and cryopreservation was examined in 5 ejaculates from each of 6 stallions and in spermatozoa recovered from the cauda epididymidis after castration of these stallions. The percentage of progressively motile spermatozoa, examined by subjective estimation (cooled samples) or by computerized analysis (frozen-thawed samples), was used as parameter. In ejaculated semen samples containing 5 and 25% seminal plasma in a skim milk glucose extender, the lower amount of seminal plasma supported spermatozoa...
Freezability and fertility results with uncentrifuged stallion semen. The first (1 to 3) sperm-rich fractions of the ejaculate were collected from 4 stallions using an open-ended vagina. The volume of the collected fractions was 12 +/- 8 ml with a density of 475 +/- 200 million spermatozoa/ml. Before freezing, the semen was diluted with a skim-milk based extender 1:1 to 1:8 (volume of semen: volume of extender), depending on the initial sperm concentration to achieve a final concentration of 100 million/ml. The total number of spermatozoa in an insemination dose ranged from 0.7 to 1 billion spermatozoa. Within 12 h after ovulation, 48 mares were inseminated in 7...
Equine plasminogen polymorphism: allelic frequencies in 23 breeds. A modified procedure for detection of the two alleles of equine plasminogen using Western blotting methods following polyacrylamide gel isoelectric focusing is described. Gene frequencies in 23 breeds and Equus przewalskii are provided.
The Horserace Betting Levy Board’s code of practice for equine viral arteritis for the 1994 breeding season. The Horserace Betting Levy Board formulates codes of practice for the control of contagious equine metritis and other equine bacterial venereal diseases, and equine viral arteritis and equid herpesvirus 1. This year's codes have just been published and the code of practice for EVA, reproduced below, has been substantially amended following the recent outbreak in the UK. The code is intended for use by veterinary surgeons and breeders of thoroughbred and non-thoroughbred horses. The HBLB states that its recommendations represent the minimum measures necessary to monitor for the presence of equi...
Deficit of inhibitory glycine receptors in spinal cord from Peruvian Pasos: evidence for an equine form of inherited myoclonus. Inherited myoclonus in Poll Hereford calves and spasticity in the spastic mouse (spa/spa) are characterized by myoclonic jerks of the skeletal musculature which occur spontaneously and in response to sensory stimuli, symptoms resembling those in subconvulsive strychnine poisoning. The primary, biochemical defect in these myoclonic animals is a deficit of inhibitory glycine receptors in the central nervous system. We now report the occurrence of similar stimulus-induced myoclonus in individual, pure-bred Peruvian Paso horses and an associated, specific deficiency in the density of [3H]strychnin...
Accumulation of allantoin and uric acid in plasma of exercising trotters. Plasma concentrations of hypoxanthine, uric acid, and allantoin, which are breakdown products of adenine nucleotides, were measured in Standardbred and Finnhorse trotters during and after an exercise test on a high-speed treadmill, after an incremental exercise test performed on a racetrack, and after a racing competition. Fiber-type composition of the middle gluteal muscle and the muscle concentrations of adenine nucleotides and inosine monophosphate were measured after the racetrack test. Changes in the concentration of hypoxanthine were not observed in any of the tests. Peak concentration o...
Automated morphometric analysis of stallion spermatozoa. Tissue variation in microscope slides made for spermatozoon analysis and variation introduced by the subjective techniques used to analyze these slides reduce the statistical power of studies that seek to use spermatozoon morphology to predict fertility. A simple specimen preparation method was developed to standardize stallion spermatozoon morphologic smears, and a new, automated spermatozoa morphometry instrument was used to objectively analyze the efficacy of the specimen preparation technique. The method achieved a standard spermatozoon concentration and reduced field-to-field variation in...
Age-related characteristics of gastric squamous epithelial mucosa in foals. Specimens of grossly normal gastric stratified squamous epithelial mucosa adjacent to the margo plicatus on the right side and along the greater curvature were obtained from 7 foetuses, 10 term foals and 12 foals 2-35 days old. Gastric squamous epithelium from the foetuses changed markedly during gestation. At 150-270 days, the epithelium was 8-10 cells thick, with a single layer of basal cells. Epithelial cells were polyhedral and had abundant clear or slightly stained cytoplasm. In the 300-day foetus the basal layer was thicker, epithelial cells were polyhedral, and there was a flattened 1 c...
Rapid evolution of horse satellite DNA. The major satellite of the horse genome consists of about 1 million copies of a 221-bp tandem repeat unit. By fluorescence in situ hybridization it has been localized in the centromeres of 58 of the 64 horse chromosomes. The donkey genome contains a similar but not identical satellite. Strikingly, the equine repeat did not hybridize to DNA of the Grevy zebra, despite the divergence of the horse and zebra only 3 to 5 million years ago and the ability of these species to crossbreed. The evolution of satellite DNA in the Equidae is more rapid than that in other mammalian families, which may be ex...
Muscle fiber type composition and fiber size in successfully and unsuccessfully endurance-raced horses. Triplicate biopsies from three different depths of the gluteus medius muscle were obtained in 36 endurance-raced horses, aged 8.42 +/- 2.85 yr. Twenty of the horses were considered excellent endurance performers according to the mean speed of their three fastest records in endurance events for the past 2 or 3 years, whereas 16 were moderate performers, with a mean racing speed < 12.5 km/h (in 120- to 180-km endurance rides), < 14 km/h (in 80- to 120-km endurance rides), or < 13.5 km/h (in 40- to 60-km endurance rides). Significant differences in muscle fiber type composition and fiber size wer...
Capacitation-like membrane changes and prolonged viability in vitro of equine spermatozoa cultured with uterine tube epithelial cells. Reliable capacitation of equine spermatozoa has been a major obstacle in the development of equine in vitro fertilization. Experiments were done to compare in vitro capacitation of equine spermatozoa by use of heparin/caffeine, calcium ionophore, uterine tube epithelial cell (UTEC)-conditioned medium, and direct culturing of spermatozoa with UTEC (coculturing). Capacitation-like changes, as determined by chlortetracycline membrane staining patterns, developed with UTEC-conditioned medium and coculturing, equivalent to that with calcium ionophore. Both of these treatments induced more (P < 0.05...
Ultrasonographic measurement of stallion accessory sex glands and excurrent ducts during seminal emission and ejaculation. Accessory sex gland and excurrent duct activity of 10 stallions was visualized with transrectal ultrasonography during seminal emission and ejaculation. First and last penile urethral contractions were defined as the start (0 sec) and end of ejaculation, respectively. Duration of ejaculation (n = 63 ejaculations) averaged 6.15 +/- 2.98 sec. Penile urethral contractions occurred an average of 6.2 +/- 2.2 times per ejaculation. Right bulbourethral glands (n = 19 ejaculations) alternated repeatedly from ovoid to flattened, irregular shapes during ejaculation. Cross-sectional area of right bulbour...
Reproductive performance of thoroughbred mares on six commercial stud farms. The records of 1630 mare years from 6 Thoroughbred stud farms in south eastern Australia were analysed for the years 1981 to 1986. Overall pregnancy and foaling rates were 83.9% and 69.3%, respectively. When calculated per served oestrous cycle, pregnancy and foaling rates were 54.7% and 43.1%, respectively. Pregnancy and foaling rates were higher (P < 0.001) for mares 3 to 10 years of age than for older mares. There was no difference in the pregnancy rates of maiden, barren and foaling mares. The foaling rate was significantly higher (P < 0.001) in mares that became pregnant during the ...
[Reproduction data in breeding mares, diseases and losses among suckling foals and preventive husbandry in German stud farms]. By means of a survey, the reproductive rate of mares and the foal losses in ten Thoroughbred, Saddlebred and Pony studs in Germany, mainly from North-Rhine-Westfalia, were collected and evaluated. Data for the survey were recorded for 1985-1990. The study also examined the hygienic management in the surveyed studs, and the morbidity rate of suckling foals was obtained for 1990. In addition to the survey questionnaire each stud was visited once. Two studs of each horse group were visited several times every week from March to August in order to evaluate as exactly as possible the husbandry and ...
Validation of an acrosomal stain for equine sperm that differentiates between living and dead sperm. An acrosomal staining technique that can differentiate between living and dead sperm was developed for equine sperm. The fluoresceinated lectin Pisum sativum agglutinin (FITC-PSA) was used to identify the presence or absence of acrosomal contents, while the supravital nuclear dye Hoechst 33258 (H258) was used to assess viability. The accuracy of the FITC-PSA acrosomal stain was tested by comparing the percentage of sperm that had lost their acrosomal contents, detected by the staining method, with that detected by transmission electron microscopy (TEM). Following capacitation in vitro, the acr...
Growth hormone secretion in the horse: unusual pattern at birth and pulsatile secretion through to maturity. A heterologous radioimmunoassay was developed and validated for the measurement of horse GH in plasma. It utilized recombinant-derived bovine GH as the radiolabelled ligand, a guinea-pig anti-porcine GH serum as first antibody and pituitary-derived horse GH as standard. Cross-reactivities were high with all of the pituitary and recombinant-derived GH preparations tested (49-140%) and very low (< 0.3%) with horse FSH, LH and prolactin. A synthetic analogue of GH-releasing factor(1-29) stimulated the expected pattern of GH release in foals. Plasma GH concentrations in foals were low at birth (< ...
X-ray and primary structure of horse serum albumin (Equus caballus) at 0.27-nm resolution. The amino-acid sequence and three-dimensional structure of equine serum albumin have been determined. The amino-acid sequence was deduced from cDNA isolated from equine liver. Comparisons of the primary structure of equine serum albumin with human serum albumin and bovine serum albumin reveal 76.1% and 73.9% sequence identity, respectively. The three-dimensional structure was determined crystallographically by the molecular-replacement method using molecular coordinates from the previously determined structure of human serum albumin, to a resolution of 0.27 nm. In accordance with the primary s...
Localization of xanthine dehydrogenase mRNA in horse skeletal muscle by in situ hybridization with digoxigenin-labelled probe. In situ hybridization was used to localize xanthine dehydrogenase (XDH) mRNA in horse skeletal muscle. Capillary endothelial cells were found to express XDH, but muscle cells did not give any signal. The digoxigenin-labelled probe was produced by PCR with primers based on the cDNA sequence of mouse XDH and horse lung cDNAs. A 4.3 kb mRNA was detected in a Northern blot.
Proceedings of the John P. Hughes International Workshop on Equine Endometritis. Davis, California, August 1992. The paper is a report from a workshop discussing equine endometritis, a condition affecting horse fertility. The event was held in honor of Professor John Hughes and his significant contributions […]
