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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.
Population genetics of Great Basin feral horses. The genetic make-up of Great Basin wild (feral) horses was investigated by blood typing studies. Blood samples of 975 feral horses from seven trap sites in Nevada and Oregon were tested by serological and electrophoretic techniques for genetic markers at 19 polymorphic loci. The average number of variants for the seven feral populations [72.1 +/- 3.2 (SEM), range 62-85] was not significantly different from that of 16 domestic breeds (75.0 +/- 11.5, range 58-105). The expected average frequency of heterozygotes per locus (average heterozygosity) for the feral populations (0.402 +/- 0.009, range...
Cloning and sequencing of the equine testicular follitropin receptor. To investigate the possibility that specific structural determinants within the equine follitropin receptor (eFSHR) are critical to the enhanced specificity of this receptor compared to other FSHRs, we used the RACE-PCR technique to clone the eFSHR from equine testis. Sequence analysis revealed that the eFSHR is highly homologous to other mammal FSHRs, but it presents 10 unique amino acid residue replacements in the extracellular domain. Furthermore, a potential N-glycosylation site was detected at a position not encountered in other receptors. Northern blot analysis identified three transcrip...
Postoperative racing performance in standardbreds and thoroughbreds with osteochondrosis of the tarsocrural joint: 109 cases (1984-1990). Medical records for 64 Thoroughbred and 45 Standardbred horses with osteochondrosis dissecans (OCD) of the tarsocrural joint that were treated by means of arthroscopic removal of the fragments before 2 years of age and before beginning racing were reviewed. Lesion site was recorded for all horses. The other foals from the dams of these surgically treated horses (siblings) were identified from mare progeny records. Racing data, including number of starts and money won during the 2- and 3-year-old racing years were obtained from the Jockey Club and the United States Trotting Association for affe...
Dominant inheritance of overo spotting in paint horses. Analysis of selected studbook records of the American Paint Horse Association, consisting of 687 foals sired by 13 overo stallions from non-overo mares, supports the inheritance of overo spotting as an autosomal dominant gene. More than one gene may control patterns registered as overo. Additional studies are necessary to explain the sporadic occurrence of overo spotting from nonspotted quarter horse parents and to confirm the inheritance of overo spotting in other breeds.
Seasonal and epididymal maturation of stallion spermatozoa. Epididymal sperm maturation in the stallion was analysed using eight epididymides and deferent ducts from healthy animals. Samples were obtained in June-July and October-November (resting and breeding periods, respectively). Epididymides were divided into head, body and tail. Sperm samples were submitted to a routine seminogram, chromatin decondensation test (Lung, 1972) and sperm velocity determination (Makler, 1980). Results demonstrate that stallion spermatozoa achieve maturation in the transition between the head and body of the epididymis as revealed by chromatin decondensation. Objective...
Kinematic detection of superior gait quality in young trotting warmbloods. This study was conducted to identify objective criteria to select young horses with a good gait, which is a prerequisite for good performance in adult horses. The trot of 24 26-month-old Dutch Warmbloods, led on a loose shank, was subjectively scored by a judge and objectively assessed on a treadmill by using kinematic analysis equipment. It appeared that forelimb and hind limb stride and swing duration, scapula rotation, forelimb maximal fetlock extension, forelimb maximal retraction, hind limb maximal protraction, maximal stifle flexion, and maximal tarsal flexion significantly correlated wi...
Characterization of a red blood cell antigen in donkeys and mules associated with neonatal isoerythrolysis. A red cell antigen of donkeys and mules was identified using antibodies in serum from a mare which produced a mule foal affected with neonatal isoerythrolysis (NI). Subsequently antibodies with similar activity were identified in the sera of other mares which had produced mule foals and were produced by immunization of horses with blood from donkeys. The antigen detected by these antibodies does not correspond to any recognized horse red cell alloantigen. This may be a xenoantigen since all donkeys (and mules) tested have shared this antigen and all horses tested have lacked the antigen. The r...
Selection of quarter horses affected with hyperkalemic periodic paralysis by show judges. Thirty offspring of a Quarter Horse sire, affected by hyperkalemic periodic paralysis (HPP), were examined electromyographically. On the basis of the detection of or lack of spontaneous activity with high frequency myotonic or pseudomyotonic discharges, the horses were diagnosed as being affected (14 horses) or unaffected (16 horses) with HPP. The show performance of these horses was evaluated for the first 3 to 9 years of their life by use of American Quarter Horse Association records. Horses affected with HPP performed significantly (P < 0.01) better in halter classes than did unaffected ...
Congenital choanal restriction in 3 horses. This study investigates the rare congenital defect known as atresia choana in horses, a condition that obstructs the animals’ nose breathing. The research centers on three horses with this condition. [...]
A new phenogroup in the horse D system of red cell alloantigens found in the Caspian pony. A new D blood group phenogroup consisting of the specificities adeo was observed in a stallion family of Caspian ponies from Iran. An additional six undescribed genetic variants were seen in a total of 82 Iranian horses. This result suggests extensive new genetic variation may be present in domestic horses from geographic regions that have not yet received scientific attention.
Parentage testing and linkage analysis in the horse using a set of highly polymorphic microsatellites. Ten (TG)n positive clones, isolated from an equine genomic library and sequenced, contained 12-19 uninterrupted TG repeats. Primers for polymerase chain reaction (PCR) were synthesized and nine of these (TG)n loci (HTG7-15) were successfully amplified and utilized in this study together with five previously reported equine microsatellite loci (HTG2-6). The PCR products were analysed by polyacrylamide gel electrophoresis followed by automated laser fluorescence detection or autoradiography. All microsatellites showed polymorphism and stable Mendelian inheritance. Differences in microsatellite v...
Genetic blood markers in Arabian, Barb and Arab-Barb horses in Morocco. Gene frequencies at 16 blood group and protein polymorphism loci (A, C, D, K, P, Q, U, Al, Gc, Es, A1B, Tf, PGD, PGM, GPI and Pi) are given for three horse breeds in Morocco (Arabian, Arab-Barb and Barb). These data are used to calculate average heterozygosity (h), Nei's standard genetic distance (DN) and probability of exclusion (PE). Variability expressed as the average heterozygosity was lower in the Arabian (0.330 +/- 0.066), while it was higher and almost the same in the Arab-Barb (0.413 +/- 0.071) and the Barb (0.414 +/- 0.070). The shortest genetic distance was found between Barb and Ar...
Genetics of racing performance in the Japanese Thoroughbred horse:: II. Environmental variation of racing time on turf and dirt tracks and the influence of sex, age, and weight carried on racing time. Data collected by the Japan Racing Association (JRA) were individual horse racing times at eight racecourses (Hakodate, Fukushima, Niigata, Tokyo, Nakayama, Chukyo, Kyoto and Hanshin) and at five distances (1000 m, 1200 m, 1400 m, 1600 m, and 1800 m) from 1982 to 1990. Important sources of variation in racing time were examined using a nested model and expressing the variance components as percentages of the total on both turf and dirt. At all racecourses and at all distances where races were on both turf and dirt, racing times were less on turf than dirt. Differences were from 2.09s to 3.91s ...
Genetics of racing performance in the Japanese Thoroughbred horse:: I. Description of the data. The Japan Racing Association (JRA) operates 10 national racecourses with both turf and dirt tracks. JRA formulates the rules for horseracing; registers owners, colors, and horses using foal registration; and licenses all JRA trainers and jockeys. In 1990, at the 10 racecourses there were 288 racing days, 3,353 races, and some 38,397 horses. Horse breeding is concentrated in 7 locations with 93% of the Thoroughbreds foaled each year coming from Hokkaido. Thoroughbred flat racing comprise 92% of all races held. Two year olds race together and nearly 40% of their races are run at 1200 m. Some 39%...
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...
