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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.
Modern Techniques for Semen Evaluation. Stallion semen evaluation is an important part of the breeding soundness evaluation. The results of the semen evaluation cannot be interpreted without a thorough knowledge of the mare and management effects that may have played a role or may affect the potential fertility of the stallion evaluated. There are considerations and limitations that the clinician should understand about each test. Any sperm quality test must be interpreted with a clear understanding of how it relates to fertility.
Mitochondrial ATP is required for the maintenance of membrane integrity in stallion spermatozoa, whereas motility requires both glycolysis and oxidative phosphorylation. To investigate the hypothesis that oxidative phosphorylation is a major source of ATP to fuel stallion sperm motility, oxidative phosphorylation was suppressed using the mitochondrial uncouplers CCCP and 2,4,-dinitrophenol (DNP) and by inhibiting mitochondrial respiration at complex IV using sodium cyanide or at the level of ATP synthase using oligomycin-A. As mitochondrial dysfunction may also lead to oxidative stress, production of reactive oxygen species was monitored simultaneously. All inhibitors reduced ATP content, but oligomycin-A did so most profoundly. Oligomycin-A and CCCP also sign...
Dwarfism with joint laxity in Friesian horses is associated with a splice site mutation in B4GALT7. Inbreeding and population bottlenecks in the ancestry of Friesian horses has led to health issues such as dwarfism. The limbs of dwarfs are short and the ribs are protruding inwards at the costochondral junction, while the head and back appear normal. A striking feature of the condition is the flexor tendon laxity that leads to hyperextension of the fetlock joints. The growth plates of dwarfs display disorganized and thickened chondrocyte columns. The aim of this study was to identify the gene defect that causes the recessively inherited trait in Friesian horses to understand the disease proce...
Genetic characterization of the Miyako horse based on polymorphisms of microsatellites and mitochondrial DNA. To help plan conservation of the endangered Miyako horse, a biological resource of the Miyako Islands in Japan, we characterized the genetics of the breed by genotyping 32 microsatellites and identifying mitochondrial DNA haplotypes. We also calculated genetic distances between individuals based on the proportion of shared alleles and visualized the genetic relationships with a phylogenetic tree. Two important results were obtained. One is that accurate pedigree registration of the horse by using microsatellites is possible, as the exclusion power of parentage testing is 0.999998. Another is t...
Relationships among stallion fertility and semen traits using estimated breeding values of German Warmblood stallions. A high quality of stallion semen is of particular importance for maximum reproductive efficiency. In the present study, we estimated the relationships among estimated breeding values (EBVs) of semen traits and EBVs for the paternal component of the pregnancy rate per estrus cycle (EBV-PAT) for 100 German Warmblood stallions using correlation and general linear model analyses. The most highly correlated sperm quality trait was total number of progressively motile sperm (r = 0.36). EBV-PAT was considered in three classes with stallions 1 SD below (120) the population mean of 100. The general lin...
The Evolutionary Origin and Genetic Makeup of Domestic Horses. The horse was domesticated only 5.5 KYA, thousands of years after dogs, cattle, pigs, sheep, and goats. The horse nonetheless represents the domestic animal that most impacted human history; providing us with rapid transportation, which has considerably changed the speed and magnitude of the circulation of goods and people, as well as their cultures and diseases. By revolutionizing warfare and agriculture, horses also deeply influenced the politico-economic trajectory of human societies. Reciprocally, human activities have circled back on the recent evolution of the horse, by creating hundreds...
Strategies for Processing Semen from Subfertile Stallions for Cooled Transport. Subfertility can be a confusing term because some semen of good quality can have reduced fertility following cooled transport if the semen is processed in an improper manner. General procedures aimed at processing stallion semen for cooled transport are well described. An array of factors could exist in reduced fertility of cool-transported semen. This article focuses on centrifugation techniques that can be used to maximize sperm quality of stallions whose semen is intended for cooled transport. Clinical cases are also provided for practical application of techniques.
Genetic diversity and population structure of Kazakh horses (Equus caballus) inferred from mtDNA sequences. The Kazakh horse is an important old horse breed in Xinjiang. They have contributed greatly to the breeding and improvement of other local horse breeds, yet their genetic diversity and population structure are not well understood. In the present study, we evaluated the genetic diversity of Kazakh horses and their relationship with other horse breeds using the mtDNA D-loop region, Cyt b gene, and a DNA fragment (nps 7974-9963, containing COX3, tRNA-Gly, ND3, and tRNA-Arg). A total of 130 Kazakh horses from 8 populations in China and Kazakhstan were analyzed. A total of 88 haplotypes (haplotype ...
Risk factors associated with fatal injuries in Thoroughbred racehorses competing in flat racing in the United States and Canada. OBJECTIVE To identify risk factors associated with fatal injuries in Thoroughbred racehorses in the United States and Canada. DESIGN Retrospective study. ANIMALS 1,891,483 race starts by 154,527 Thoroughbred racehorses at 89 racetracks in the United States and Canada from 2009 to 2013. PROCEDURES Data were extracted from the Equine Injury Database, which contained information for 93.9% of all official flat racing events in the United States and Canada during the 5-year observation period. Forty-four possible risk factors were evaluated by univariate then multivariable logistic regression to id...
Variability of lysozyme and lactoferrin bioactive protein concentrations in equine milk in relation to LYZ and LTF gene polymorphisms and expression. Equine milk is considered to be an interesting product for human nutrition, mainly owing to its low allergenicity and significant amounts of bioactive proteins, including lysozyme (LYZ) and lactoferrin (LTF). The present study assessed the effect of genetic factors on LYZ and LTF concentration variability in mare's milk. Results: Significant effects of horse breed and lactation stage on milk LYZ and LTF contents were observed. The highest level of LTF and the lowest concentration of LYZ were recorded for the Polish Warmblood Horse breed. The highest amounts of both proteins were found for the ...
Genotyping of German and Austrian Taylorella equigenitalis isolates using repetitive extragenic palindromic (REP) PCR and pulsed-field gel electrophoresis (PFGE). A total of 124 Taylorella (T.) equigenitalis and five T. asinigenitalis field isolates collected between 2002 and 2014 were available for genotyping using REP- (repetitive extragenic palindromic) PCR and PFGE (pulsed-field gel electrophoresis). The study comprised 79 T. equigenitalis field isolates originating from ten defined breeds of German horses and revealed a spectrum of five REP (rep-E1-E4, rep-E3a) and 15 PFGE (TE-A1-A9, TE-B1-B3, TE-C, TE-E1, and TE-E2) genotypes. T. equigenitalis field isolates (n=40) obtained from Austrian Lipizzaner horses were differentiated into three REP (rep-E1...
Heritability and factors associated with number of harness race starts in the Spanish Trotter horse population. Longevity/durability is a relevant trait in racehorses. Genetic analysis and knowledge of factors that influence number of harness race starts would be advantageous for both horse welfare and the equine industry. Objective: To perform a genetic analysis on harness racing using number of races as a measure of longevity/durability and to identify factors associated with career length in Spanish Trotter Horses (STH). Methods: Longitudinal study. Methods: Performance data (n = 331,970) on the STH population for harness racing at national level between 1990 and 2014 were used. A grouped data model ...
Sequence variants of BIEC2-808543 near LCORL are associated with body composition in Thoroughbreds under training. Ligand-dependent nuclear receptor compressor-like (LCORL) encodes a transcription factor, and its polymorphisms are associated with measures of skeletal frame size and adult height in several species. Recently, the single nucleotide polymorphism (SNP) BIEC2-808543 located upstream of LCORL was identified as a genetic diagnostic marker associated with withers height in Thoroughbreds. In this study, 322 Thoroughbreds-in-training were genotyped for BIEC2-808543 to evaluate the association between genotype and body composition traits, including body weight, withers height, the ratio of body weight...
Rosiglitazone Improves Stallion Sperm Motility, ATP Content, and Mitochondrial Function. Media used for equine sperm storage often contain relatively high concentrations of glucose, even though stallion spermatozoa preferentially utilize oxidative phosphorylation (OXPHOS) over glycolysis to generate ATP and support motility. Rosiglitazone is an antidiabetic compound that enhances metabolic flexibility and glucose utilization in various cell types, but its effects on sperm metabolism are unknown. This study investigated the effects of rosiglitazone on stallion sperm function in vitro, along with the possible role of AMP-activated protein kinase (AMPK) in mediating these effects. Sp...
Equivalent seminal characteristics in human and stallion at first and second ejaculated fractions. Sperm quality was assessed in normozoospermic human (n = 10) and Spanish breed stallion (n = 10) after sperm fractionation during ejaculation. The first ejaculated fraction was separated from the second. A third sample was reconstituted using equivalent proportion of both fractions (RAW). Fraction 1, Fraction 2 and RAW semen were incubated for 30 min at 37°C to homogenise the impact of iatrogenic damage between both species. Sperm concentration, motility and sperm DNA damage were assessed in each fraction and RAW semen. The results showed two important facts: (i) spermatozoa confined at ...
Detection of single nucleotide polymorphisms (SNP) in equine coat color genes using SNaPshotTM multiplex kit or pluronic F-108 tri-block copolymer and capillary electrophoresis. Molecular methods for the detection of mammalian coat color phenotypes have expanded greatly within the past decade. Many phenotypes are associated with a single nucleotide polymorphism mutation in the genetic sequence. Traditionally, these mutations are detected through sequencing, hybridization assays or mini-sequencing. However, these techniques can be expensive and tedious. Previously, CE-SSCP using the F-108 polymer was able to distinguish SNPs for the melanocortin-1 receptor (mc1r) coat color gene in horses (Equus caballus) that differed by one nucleotide substitution. The objective of t...
An Intronic MBTPS2 Variant Results in a Splicing Defect in Horses with Brindle Coat Texture. We investigated a family of horses exhibiting irregular vertical stripes in their hair coat texture along the neck, back, hindquarters, and upper legs. This phenotype is termed "brindle" by horse breeders. We propose the term "brindle 1 (BR1)" for this specific form of brindle. In some BR1 horses, the stripes were also differentially pigmented. Pedigree analyses were suggestive of a monogenic X-chromosomal semidominant mode of inheritance. Haplotype analyses identified a 5 Mb candidate region on chromosome X. Whole genome sequencing of four BR1 and 60 nonbrindle horses identified 61 private v...
Heritability and prevalence of selected osteochondrosis lesions in yearling Thoroughbred horses. Osteochondrosis is considered multifactorial in origin, with factors such as nutrition, conformation, body size, trauma and genetics thought to contribute to its pathogenesis. Few studies have investigated the effects of genetic variability of osteochondrosis in Thoroughbreds. Objective: To describe the prevalence and genetic variability of a subset of osteochondrosis lesions in a group of Thoroughbred yearlings. Methods: Retrospective cohort study. Methods: Radiographs of 1962 Thoroughbred yearlings were retrieved from clinical records obtained between 2005 and 2013. Pedigree information was ...
Genetic diversity of Thoroughbred horse population from Bosnia and Herzegovina based on 17 microsatellite markers. The focus of this study was on genetic diversity of TB horse population raised in B&H. Genomic DNA was genotyped by using 17 microsatellite markers. A total of 103 alleles were detected. The average number of alleles per locus was 6.059 and effective number of alleles was 3.293. Means of observed and expected heterozygosity were calculated 0.645 and 0.696, respectively. The average PIC values was 0.649 and inbreeding coefficient was 0.090. Based on all observed parameters, ASB2 locus showed the highest genetic diversity while locus HMS2 was the least diverse. These results suggest that the...
A highly prevalent equine glycogen storage disease is explained by constitutive activation of a mutant glycogen synthase. Equine type 1 polysaccharide storage myopathy (PSSM1) is associated with a missense mutation (R309H) in the glycogen synthase (GYS1) gene, enhanced glycogen synthase (GS) activity and excessive glycogen and amylopectate inclusions in muscle. Equine muscle biochemical and recombinant enzyme kinetic assays in vitro and homology modelling in silico, were used to investigate the hypothesis that higher GS activity in affected horse muscle is caused by higher GS expression, dysregulation, or constitutive activation via a conformational change. PSSM1-affected horse muscle had significantly higher gly...
[A case of 63,X/64,XX mosaicism in a subfertile pony mare]. The present case report describes a 6-year old subfertile pony mare, which became pregnant after the eleventh artificial insemination. The examination of the ovaries and the uterus did not reveal any abnormal clinical findings and the mare showed a regular oestrous cycle. Based on cytogenetic and molecular genetic analyses it became possible to elucidate the observed subfertility. The mosaic karyotype of the mare consisted of 63,X (20%) and 64,XX (80%) cells. A PCR analysis failed to amplify sequences from the equine SRY gene. The observed classic 63,X/64,XX mosaicism is a plausible explanatio...
[Horse, cow and reindeer were converted into arctic domestic animals]. Domestic animal production in the arctic region is often thought to be based exclusively on reindeer herding. There are, however, regions in Northern Europe and Siberia having a long tradition in rearing breeds of cattle and horse adapted to the northers conditions also. The development of these arctic animal breeds has been largely founded on old tradition rather than on the programs of breeding organizations. As a result of the selection carried out by nature and man, the domestic animals of arctic regions express characteristics that are metabolic, structural, associated with reproductive p...
Alkaline phosphatase added to capacitating medium enhances horse sperm-zona pellucida binding. Alkaline phosphatase (AP) is present in equine seminal plasma and spermatozoa, but its functional role is not fully understood yet. Being that, sperm-oocyte interaction in equine species has been reported to be enhanced at a slightly basic pH, this work aimed at verifying whether exogenous alkaline phosphatase exerts any role on stallion spermatozoa and sperm-oocyte interaction at different pHs (7.4; 8.0; 9.0). Stallion spermatozoa were capacitated in Tyrode's medium at pH 7.4, 8.0, and 9.0 for 4 hours at 38 °C, 5% CO with 2.5-IU AP (AP group) or without AP (capacitated spermatozoa group); ...
The origin of ambling horses. Horseback riding is the most fundamental use of domestic horses and has had a huge influence on the development of human societies for millennia. Over time, riding techniques and the style of riding improved. Therefore, horses with the ability to perform comfortable gaits (e.g. ambling or pacing), so-called 'gaited' horses, have been highly valued by humans, especially for long distance travel. Recently, the causative mutation for gaitedness in horses has been linked to a substitution causing a premature stop codon in the DMRT3 gene (DMRT3_Ser301STOP) [1]. In mice, Dmrt3 is expressed in spinal...
Pigment retinopathy in warmblood horses with equine degenerative myeloencephalopathy and equine motor neuron disease. A pigment retinopathy has been reported in adult horses with equine motor neuron disease (EMND) arising from chronic α-tocopherol (α-TP) deficiency. A pigment retinopathy has not been identified in horses with neuroaxonal dystrophy/equine degenerative myeloencephalopathy (NAD/EDM) that affects genetically susceptible young horses with α-TP deficiency. The objective of this report is to describe, for the first time, a pigment retinopathy in a family of α-TP-deficient Warmbloods (WB) with clinically apparent NAD/EDM or EMND. Unassigned: Twenty-five WB horses from one farm underwent complete ...
Heritability of Recurrent Exertional Rhabdomyolysis in Standardbred and Thoroughbred Racehorses Derived From SNP Genotyping Data. Recurrent exertional rhabdomyolysis (RER) in Thoroughbred and Standardbred racehorses is characterized by episodes of muscle rigidity and cell damage that often recur upon strenuous exercise. The objective was to evaluate the importance of genetic factors in RER by obtaining an unbiased estimate of heritability in cohorts of unrelated Thoroughbred and Standardbred racehorses. Four hundred ninety-one Thoroughbred and 196 Standardbred racehorses were genotyped with the 54K or 74K SNP genotyping arrays. Heritability was calculated from genome-wide SNP data with a mixed linear and Bayesian model, ...
Association between population structure and allele frequencies of the glycogen synthase 1 mutation in the Austrian Noriker draft horse. The aim of this study was to determine the allele frequency of the glycogen synthase 1 (GYS1) mutation associated with polysaccharide storage myopathy type 1 in the Austrian Noriker horse. Furthermore, we examined the influence of population substructures on the allele distribution. The study was based upon a comprehensive population sample (208 breeding stallions and 309 mares) and a complete cohort of unselected offspring from the year 2014 (1553 foals). The mean proportion of GYS1 carrier animals in the foal cohort was 33%, ranging from 15% to 50% according to population substructures based...
Risk Factors for Equine Gastric Glandular Disease: A Case-Control Study in a Finnish Referral Hospital Population. Equine gastric glandular disease (EGGD) is a term used to classify erosive and ulcerative diseases of the glandular mucosa of the equine stomach. Epidemiologic studies of risk factors for EGGD have not been reported. Objective: To determine risk factors for EGGD. Methods: Cases (n = 83) had endoscopic evidence of EGGD; controls (n = 34) included healthy horses and horses with equine squamous gastric disease (ESGD) without EGGD. Methods: Retrospective case-control study. The data were analyzed by multivariable logistic regression modeling. Analysis was performed on the full dataset. An addi...
