RESUMEN
The control of transcription is crucial for homeostasis in mammals. A previous selective sweep analysis of horse racing performance revealed a 19.6 kb candidate regulatory region 50 kb downstream of the Endothelin3 (EDN3) gene. Here, the region was narrowed to a 5.5 kb span of 14 SNVs, with elite and sub-elite haplotypes analyzed for association to racing performance, blood pressure and plasma levels of EDN3 in Coldblooded trotters and Standardbreds. Comparative analysis of human HiCap data identified the span as an enhancer cluster active in endothelial cells, interacting with genes relevant to blood pressure regulation. Coldblooded trotters with the sub-elite haplotype had significantly higher blood pressure compared to horses with the elite performing haplotype during exercise. Alleles within the elite haplotype were part of the standing variation in pre-domestication horses, and have risen in frequency during the era of breed development and selection. These results advance our understanding of the molecular genetics of athletic performance and vascular traits in both horses and humans.
Asunto(s)
Rendimiento Atlético , Presión Sanguínea , Haplotipos , Caballos/genética , Animales , Humanos , Presión Sanguínea/genética , Rendimiento Atlético/fisiología , Haplotipos/genética , Endotelina-3/genética , Polimorfismo de Nucleótido Simple , Alelos , Masculino , Células Endoteliales/metabolismoRESUMEN
BACKGROUND: The Franches-Montagnes (FM) is the last native horse breed of Switzerland, established at the end of the 19th century by cross-breeding local mares with Anglo-Norman stallions. We collected high-density SNP genotype data (Axiom™ 670 K Equine genotyping array) from 522 FM horses, including 44 old-type horses (OF), 514 European Warmblood horses (WB) from Sweden and Switzerland (including a stallion used for cross-breeding in 1990), 136 purebred Arabians (AR), 32 Shagya Arabians (SA), and 64 Thoroughbred (TB) horses, as introgressed WB stallions showed TB origin in their pedigrees. The aim of the study was to ascertain fine-scale population structures of the FM breed, including estimation of individual admixture levels and genomic inbreeding (FROH) by means of Runs of Homozygosity. RESULTS: To assess fine-scale population structures within the FM breed, we applied a three-step approach, which combined admixture, genetic contribution, and FROH of individuals into a high-resolution network visualization. Based on this approach, we were able to demonstrate that population substructures, as detected by model-based clustering, can be either associated with a different genetic origin or with the progeny of most influential sires. Within the FM breed, admixed horses explained most of the genetic variance of the current breeding population, while OF horses only accounted for a small proportion of the variance. Furthermore, we illustrated that FM horses showed high TB admixture levels and we identified inconsistencies in the origin of FM horses descending from the Arabian stallion Doktryner. With the exception of WB, FM horses were less inbred compared to the other breeds. However, the relatively few but long ROH segments suggested diversity loss in both FM subpopulations. Genes located in FM- and OF-specific ROH islands had known functions involved in conformation and behaviour, two traits that are highly valued by breeders. CONCLUSIONS: The FM remains the last native Swiss breed, clearly distinguishable from other historically introgressed breeds, but it suffered bottlenecks due to intensive selection of stallions, restrictive mating choices based on arbitrary definitions of pure breeding, and selection of rare coat colours. To preserve the genetic diversity of FM horses, future conservation managements strategies should involve a well-balanced selection of stallions (e.g., by integrating OF stallions in the FM breeding population) and avoid selection for rare coat colours.
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Endogamia , Polimorfismo de Nucleótido Simple , Caballos/genética , Animales , Linaje , Masculino , Cruzamiento/métodos , Femenino , Suiza , Genotipo , HomocigotoRESUMEN
BACKGROUND: The pleiotropic effects of the melanocortin system show promise in overcoming limitations associated with large variations in opioid analgesic effectiveness observed in equine practice. Of particular interest is variation in the melanocortin-1-receptor (MC1R) gene, which dictates pigment type expression through its epistatic interaction with the agouti signalling protein (ASIP) gene. MC1R has previously been implicated in opioid efficacy in other species; however, this relationship is yet to be explored in horses. In this study, analgesic effectiveness was scored (1-3) based on noted response to dura penetration during the performance of cerebrospinal fluid centisis after sedation and tested for association with known genetic regions responsible for pigmentation variation in horses. RESULTS: The chestnut phenotype was statistically significant (P < 0.05) in lowering analgesic effectiveness when compared to the bay base coat colour. The 11bp indel in ASIP known to cause the black base coat colour was not significant (P>0.05); however, six single nucleotide polymorphisms (SNPs) within the genomic region encoding the ASIP gene and one within MC1R were identified as being nominally significant (P<0.05) in association with opioid analgesic effectiveness. This included the location of the known e MC1R variant resulting in the chestnut coat colour. CONCLUSIONS: The current study provides promising evidence for important links between pigmentation genes and opioid effectiveness in horses. The application of an easily identifiable phenotype indicating variable sensitivity presents a promising opportunity for accessible precision medicine in the use of analgesics and warrants further investigation.
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Analgésicos Opioides , Polimorfismo de Nucleótido Simple , Receptor de Melanocortina Tipo 1 , Animales , Caballos , Analgésicos Opioides/farmacología , Analgésicos Opioides/uso terapéutico , Receptor de Melanocortina Tipo 1/genética , Pigmentación/genética , Proteína de Señalización Agouti/genética , Masculino , Femenino , Fenotipo , Líquido Cefalorraquídeo/metabolismoRESUMEN
BACKGROUND: All Scottish Fold cats are believed to be affected by osteochondrodysplasia, a painful degenerative joint disorder. This retrospective study aimed to estimate the prevalence of osteochondrodysplasia in Scottish Fold and Scottish Straight cats in Australian veterinary clinics using electronic patient records (EPRs), collected between 1992 and 2018. RESULTS: Consultation events (34,926) in EPRs from veterinary clinics located in New South Wales, Queensland, and Victoria, were collected from 1,131 Scottish Fold and 117 Scottish Shorthair cats. A clinical diagnosis of osteochondrodysplasia was made in 12/1,131 Scottish Fold cats. Additionally, 69 cats were identified with suspected osteochondrodysplasia. Of these, 64 were Scottish Fold and 5 were Scottish Shorthair cats. Male and female cats were equally represented. However, a significant difference was observed for the age clinical signs were first recorded in the EPRs. Cats diagnosed clinically with osteochondrodysplasia were significantly younger (p < 0.0001) compared to cats identified as suspected SFOCD cases. CONCLUSIONS: Findings from this study suggest a relatively low prevalence of clinically diagnosed Scottish Fold osteochondrodysplasia (SFOCD) in the studied Australian Scottish Fold population, with cats generally diagnosed with SFOCD at less than 30 months of age. Further evidence is required to accurately assess the clinical relevance of SFOCD in the Scottish Fold population.
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Enfermedades de los Gatos , Osteocondrodisplasias , Masculino , Gatos , Femenino , Animales , Osteocondrodisplasias/veterinaria , Estudios Retrospectivos , Prevalencia , Australia , Escocia/epidemiología , Enfermedades de los Gatos/epidemiologíaRESUMEN
This review highlights a novel application of breed identification and prediction of skeletal traits in forensic investigations using canine DNA evidence. Currently, genotyping methods used for canine breed classification involve the application of highly polymorphic short tandem repeats in addition to larger commercially available SNP arrays. Both applications face technical challenges. An additional approach to breed identification could be through genotyping SNPs and indels that characterise the array of skeletal differences displayed across domestic dog populations. Research has shown that a small number of genetic variants of large effect drive differences in skeletal phenotypes among domestic dog breeds. This feature makes functionally significant canine skeletal variants a cost-effective target for forensic investigators to classify individuals according to their breed. Further analysis of these skeletal variants would enable the prediction of external appearance. To date, functionally significant genes with genetic variants associated with differences in size, bulk, skull shape, ear shape, limb length, digit type, and tail morphology have been uncovered. Recommendations of a cost-effective genotyping method that can be readily designed and applied by forensic investigators have been given. Further advances to improve the field of canine skeletal forensic DNA phenotyping include the refinement of phenotyping methods, further biological validation of the skeletal genetic variants and establishing a publicly available database for storage of allele frequencies of the skeletal genetic variants in the wider domestic dog population.
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Técnicas de Genotipaje , Polimorfismo de Nucleótido Simple , Animales , ADN/genética , Perros , Frecuencia de los Genes , FenotipoRESUMEN
BACKGROUND: The back plays a vital role in horse locomotion, where the spine functions as a spring during the stride cycle. A complex interaction between the spine and the muscles of the back contribute to locomotion soundness, gait ability, and performance of riding and racehorses. Conformation is commonly used to select horses for breeding and performance in multiple horse breeds, where the back and croup conformation plays a significant role. The conformation of back and croup plays an important role on riding ability in Icelandic horses. However, the genes behind this trait are still unknown. Therefore, the aim of this study was to identify genomic regions associated with conformation of back and croup in Icelandic horses and to investigate their effects on riding ability. One hundred seventy-seven assessed Icelandic horses were included in the study. A genome-wide association analysis was performed using the 670 K+ Axiom Equine Genotyping Array, and the effects of different haplotypes in the top associated region were estimated for riding ability and additional conformation traits assessed during breeding field tests. RESULTS: A suggestive quantitative trait loci (QTL) for the score of back and croup was detected on Equus caballus (ECA) 22 (p-value = 2.67 × 10- 7). Haplotype analysis revealed two opposite haplotypes, which resulted in higher and lower scores of the back and croup, respectively (p-value < 0.001). Horses with the favorable haplotype were more inclined to have a well-balanced backline with an uphill conformation and had, on average, higher scores for the lateral gaits tölt (p-value = 0.02) and pace (p-value = 0.004). This genomic region harbors three genes: C20orf85, ANKRD60 and LOC100056167. ANKRD60 is associated with body height in humans. C20orf85 and ANKRD60 are potentially linked to adolescent idiopathic scoliosis in humans. CONCLUSIONS: Our results show that the detected QTL for conformation of back and croup is of importance for quality of lateral gaits in Icelandic horses. These findings could result in a genetic test to aid in the selection of breeding horses, thus they are of major interest for horse breeders. The results may also offer a gateway to comparative functional genomics by potentially linking both motor laterality and back inclination in horses with scoliosis in humans.
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Marcha , Caballos/genética , Sitios de Carácter Cuantitativo , Animales , Marcha/genética , Estudio de Asociación del Genoma Completo , FenotipoRESUMEN
BACKGROUND: Horses produce only one foal from an eleven-month gestation period, making the maintenance of high reproductive rates essential. Genetic bottlenecks and inbreeding can increase the frequency of deleterious variants, resulting in reduced reproductive levels in a population. In this study we examined the influence of inbreeding levels on foaling rate, gestation length and secondary sex ratio in Australian Thoroughbred mares. We also investigated the genetic change in these traits throughout the history of the breed. Phenotypic data were obtained from 27,262 breeding records of Thoroughbred mares provided by three Australian stud farms. Inbreeding was estimated using the pedigree of each individual dating back to the foundation of the breed in the eighteenth century. RESULTS: While both gestation length and foaling rate were heritable, no measurable effect of inbreeding on either trait was found. However, we did find that the genetic value for both traits had decreased within recent generations. A number of environmental factors also had significant effects on foaling rate and gestation length. Secondary sex ratio had only an extremely small paternal heritable effect and was not susceptible to environmental influences. CONCLUSIONS: In contrast to racing performance, inbreeding had no measurable effect on foaling rate or gestation length in Australian Thoroughbred horses. This could be because the level of inbreeding in the population examined is not high enough to show a discernible effect on reproductive traits. Populations that experience higher levels of inbreeding due to use of artificial reproductive technologies or extremely small population sizes may show a more pronounced reduction in natural foaling rate or gestation length. It is also possible that the intensive management techniques used in the Thoroughbred population masks any negative effects of inbreeding. The decrease in the genetic value of foaling rate is likely to be because horses with unfavourable genetic potential have not yet been selected out of the population. The change in genetic value of gestation length may be due to selective breeding favouring horses with shorter pregnancies. We also found that prioritising the mating of older mares, and avoiding out of season mating could lead to an increased breeding success.
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Aptitud Genética/genética , Caballos/genética , Endogamia , Reproducción/genética , Animales , Cruzamiento , Femenino , Linaje , Embarazo , Razón de MasculinidadRESUMEN
BACKGROUND: Horses have been strongly selected for speed, strength, and endurance-exercise traits since the onset of domestication. As a result, highly specialized horse breeds have developed with many modern horse breeds often representing closed populations with high phenotypic and genetic uniformity. However, a great deal of variation still exists between breeds, making the horse particularly well suited for genetic studies of athleticism. To identify genomic regions associated with athleticism as it pertains to trotting racing ability in the horse, the current study applies a pooled sequence analysis approach using a unique Nordic horse model. RESULTS: Pooled sequence data from three Nordic horse populations were used for FST analysis. After strict filtering, FST analysis yielded 580 differentiated regions for trotting racing ability. Candidate regions on equine chromosomes 7 and 11 contained the largest number of SNPs (n = 214 and 147, respectively). GO analyses identified multiple genes related to intelligence, energy metabolism, and skeletal development as potential candidate genes. However, only one candidate region for trotting racing ability overlapped a known racing ability QTL. CONCLUSIONS: Not unexpected for genomic investigations of complex traits, the current study identified hundreds of candidate regions contributing to trotting racing ability in the horse. Likely resulting from the cumulative effects of many variants across the genome, racing ability continues to demonstrate its polygenic nature with candidate regions implicating genes influencing both musculature and neurological development.
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Caballos/genética , Fenotipo , Polimorfismo de Nucleótido Simple , Carrera , Animales , Cruzamiento , Metabolismo Energético , Femenino , Genoma , Estudio de Asociación del Genoma Completo , Caballos/fisiología , Inteligencia , Masculino , Modelos Animales , Desarrollo de Músculos , Análisis de Secuencia de ADNRESUMEN
BACKGROUND: Copy Number Variation (CNV) is a common form of genetic variation underlying animal evolution and phenotypic diversity across a wide range of species. In the mammalian genome, high frequency of CNV differentiation between breeds may be candidates for population-specific selection. However, CNV differentiation, selection and its population genetics have been poorly explored in horses. RESULTS: We investigated the patterns, population variation and gene annotation of CNV using the Axiom® Equine Genotyping Array (670,796 SNPs) from a large cohort of individuals (N = 1755) belonging to eight European horse breeds, varying from draught horses to several warmblood populations. After quality control, 152,640 SNP CNVs (individual markers), 18,800 segment CNVs (consecutive SNP CNVs of same gain/loss state or both) and 939 CNV regions (CNVRs; overlapping segment CNVs by at least 1 bp) compared to the average signal of the reference (Belgian draught horse) were identified. Our analyses showed that Equus caballus chromosome 12 (ECA12) was the most enriched in segment CNV gains and losses (~ 3% average proportion of the genome covered), but the highest number of segment CNVs were detected on ECA1 and ECA20 (regardless of size). The Friesian horses showed private SNP CNV gains (> 20% of the samples) on ECA1 and Exmoor ponies displayed private SNP CNV losses on ECA25 (> 20% of the samples). The Warmblood cluster showed private SNP CNV gains located in ECA9 and Draught cluster showed private SNP CNV losses located in ECA7. The length of the CNVRs ranged from 1 kb to 21.3 Mb. A total of 10,612 genes were annotated within the CNVRs. The PANTHER annotation of these genes showed significantly under- and overrepresented gene ontology biological terms related to cellular processes and immunity (Bonferroni P-value < 0.05). We identified 80 CNVRs overlapping with known QTL for fertility, coat colour, conformation and temperament. We also report 67 novel CNVRs. CONCLUSIONS: This work revealed that CNV patterns, in the genome of some European horse breeds, occurred in specific genomic regions. The results provide support to the hypothesis that high frequency private CNVs residing in genes may potentially be responsible for the diverse phenotypes seen between horse breeds.
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Variaciones en el Número de Copia de ADN/genética , Variación Genética , Genoma/genética , Caballos/genética , Animales , Cruzamiento , Hibridación Genómica Comparativa , Europa (Continente) , Evolución Molecular , Genética de Población , Genotipo , Fenotipo , Selección GenéticaRESUMEN
BACKGROUND: Since the 1950s, the Norwegian-Swedish Coldblooded trotter (NSCT) has been intensively selected for harness racing performance. As a result, the racing performance of the NSCT has improved remarkably; however, this improved racing performance has also been accompanied by a gradual increase in inbreeding level. Inbreeding in NSCT has historically been monitored by using traditional methods that are based on pedigree analysis, but with recent advancements in genomics, the NSCT industry has shown interest in adopting molecular approaches for the selection and maintenance of this breed. Consequently, the aims of the current study were to estimate genomic-based inbreeding coefficients, i.e. the proportion of runs of homozygosity (ROH), for a sample of NSCT individuals using high-density genotyping array data, and subsequently to compare the resulting rate of genomic-based F (FROH) to that of pedigree-based F (FPED) coefficients within the breed. RESULTS: A total of 566 raced NSCT were available for analyses. Average FROH ranged from 1.78 to 13.95%. Correlations between FROH and FPED were significant (P < 0.001) and ranged from 0.27 to 0.56, with FPED and FROH from 2000 to 2009 increasing by 1.48 and 3.15%, respectively. Comparisons of ROH between individuals yielded 1403 regions that were present in at least 95% of the sampled horses. The average percentage of a single chromosome covered in ROH ranged from 9.84 to 18.82% with chromosome 31 and 18 showing, respectively, the largest and smallest amount of homozygosity. CONCLUSIONS: Genomic inbreeding coefficients were higher than pedigree inbreeding coefficients with both methods showing a gradual increase in inbreeding level in the NSCT breed between 2000 and 2009. Opportunities exist for the NSCT industry to develop programs that provide breeders with easily interpretable feedback on regions of the genome that are suboptimal from the perspective of genetic merit or that are sensitive to inbreeding within the population. The use of molecular data to identify genomic regions that may contribute to inbreeding depression in the NSCT will likely prove to be a valuable tool for the preservation of its genetic diversity in the long term.
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Homocigoto , Caballos/genética , Endogamia , Sitios de Carácter Cuantitativo , Animales , Femenino , Estudio de Asociación del Genoma Completo/métodos , Caballos/fisiología , Masculino , Linaje , Selección ArtificialRESUMEN
BACKGROUND: Although harness racing is of high economic importance to the global equine industry, significant genomic resources have yet to be applied to mapping harness racing success. To identify genomic regions associated with harness racing success, the current study performs genome-wide association analyses with three racing performance traits in the Norwegian-Swedish Coldblooded Trotter using the 670 K Axiom Equine Genotyping Array. RESULTS: Following quality control, 613 horses and 359,635 SNPs were retained for further analysis. After strict Bonferroni correction, nine genome-wide significant SNPs were identified for career earnings. No genome-wide significant SNPs were identified for number of gallops or best km time. However, four suggestive genome-wide significant SNPs were identified for number of gallops, while 19 were identified for best km time. Multiple genes related to intelligence, energy metabolism, and immune function were identified as potential candidate genes for harness racing success. CONCLUSIONS: Apart from the physiological requirements needed for a harness racing horse to be successful, the results of the current study also advocate learning ability and memory as important elements for harness racing success. Further exploration into the mental capacity required for a horse to achieve racing success is likely warranted.
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Metabolismo Energético/genética , Caballos/genética , Aprendizaje , Polimorfismo de Nucleótido Simple , Carácter Cuantitativo Heredable , Animales , Femenino , Estudio de Asociación del Genoma Completo , Caballos/metabolismo , Caballos/fisiología , Caballos/psicología , MasculinoRESUMEN
BACKGROUND: Many common and relevant diseases affecting equine welfare have yet to be tested regarding structural variants such as copy number variations (CNVs). CNVs make up a substantial proportion of total genetic variability in populations of many species, resulting in more sequence differences between individuals than SNPs. Associations between CNVs and disease phenotypes have been established in several species, but equine CNV studies have been limited. Aim of this study was to identify CNVs and to perform a genome-wide association (GWA) study in Friesian horses to identify genomic loci associated with insect bite hypersensitivity (IBH), a common seasonal allergic dermatitis observed in many horse breeds worldwide. RESULTS: Genotypes were obtained using the Axiom® Equine Genotyping Array containing 670,796 SNPs. After quality control of genotypes, 15,041 CNVs and 5350 CNV regions (CNVRs) were identified in 222 Friesian horses. Coverage of the total genome by CNVRs was 11.2% with 49.2% of CNVRs containing genes. 58.0% of CNVRs were novel (i.e. so far only identified in Friesian horses). A SNP- and CNV-based GWA analysis was performed, where about half of the horses were affected by IBH. The SNP-based analysis showed a highly significant association between the MHC region on ECA20 and IBH in Friesian horses. Associations between the MHC region on ECA20 and IBH were also detected based on the CNV-based analysis. However, CNVs associated with IBH in Friesian horses were not often in close proximity to SNPs identified to be associated with IBH. CONCLUSIONS: CNVs were identified in a large sample of the Friesian horse population, thereby contributing to our knowledge on CNVs in horses and facilitating our understanding of the equine genome and its phenotypic expression. A clear association was identified between the MHC region on ECA20 and IBH in Friesian horses based on both SNP- and CNV-based GWA studies. These results imply that MHC contributes to IBH sensitivity in Friesian horses. Although subsequent analyses are needed for verification, nucleotide differences, as well as more complex structural variations like CNVs, seem to contribute to IBH sensitivity. IBH should be considered as a common disease with a complex genomic architecture.
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Caballos/genética , Hipersensibilidad/veterinaria , Mordeduras y Picaduras de Insectos/veterinaria , Animales , Variaciones en el Número de Copia de ADN , Estudio de Asociación del Genoma Completo/veterinaria , Hipersensibilidad/genética , Mordeduras y Picaduras de Insectos/genética , Polimorfismo de Nucleótido Simple , Factores de RiesgoRESUMEN
Many genes are known to have an influence on conformation and performance traits; however, the role of one gene, Myostatin (MSTN), has been highlighted in recent studies on horses. Myostatin acts as a repressor in the development and regulation of differentiation and proliferative growth of skeletal muscle. Several studies have examined the link between MSTN, conformation, and performance in racing breeds, but no studies have investigated the relationship in Icelandic horses. Icelandic horses, a highly unique breed, are known both for their robust and compact conformation as well as their additional gaits tölt and pace. Three SNPs (g.65868604G>T [PR8604], g.66493737C>T [PR3737], and g.66495826A>G [PR5826]) flanking or within equine MSTN were genotyped in 195 Icelandic horses. The SNPs and haplotypes were analyzed for association with official estimated breeding values (EBV) for conformation traits (n = 11) and gaits (n = 5). The EBV for neck, withers, and shoulders was significantly associated with both PR8604 and PR3737 (P < 0.05). PR8604 was also associated with EBV for total conformation (P = 0.05). These associations were all supported by the haplotype analysis. However, while SNP PR5826 showed a significant association with EBVs for leg stance and hooves (P < 0.05), haplotype analyses for these traits failed to fully support these associations. This study demonstrates the possible role of MSTN on both the form and function of horses from non-racing breeds. Further analysis of Icelandic horses as well as other non-racing breeds would be beneficial and likely help to completely understand the influence of MSTN on conformation and performance in horses.
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Marcha , Variación Genética , Miostatina/genética , Carácter Cuantitativo Heredable , Animales , Cruzamiento , Femenino , Estudios de Asociación Genética , Genotipo , Haplotipos , Caballos , Masculino , Fenotipo , Polimorfismo de Nucleótido SimpleRESUMEN
Previous studies showed a positive effect of the DMRT3 "gait keeper" mutation on harness racing performance in Standardbreds, French-, and Nordic trotters. The mutation has also been shown to influence riding traits in multiple breeds. This study investigated the effect of the DMRT3 mutation on harness racing performance and riding traits in Finnhorses. Finnhorses used for harness racing (n = 180) and for riding (n = 59) were genotyped for the DMRT3 mutation. For the trotters the genotypes were evaluated for association with racing performance (number of starts, victories, placings, earnings, and race times). At 3-6 years of age the AA genotype was superior compared with the CA and CC genotypes. The AA horses had a significantly higher proportion of victories (P = 1.4×10(-6)) and placings (P = 4.1×10(-7)), better race times (P = 0.01), and earned more money (P = 0.009) compared with C-horses. For the Finnhorses used for riding the owners answered a questionnaire to score how well the horse performed the gaits walk, trot, and canter on a scale from 1 to 6. These scores were tested for association with the DMRT3 genotypes. Although AA horses were more successful as racehorses, the CC and CA horses appear more adapted for classical riding disciplines. The AA horses received significantly lower gait scores compared with C-horses for the majority of gaits. Except for rhythm in extended canter (P = 0.05), there were no significant differences between CA and CC horses. This study shows that there are different optimal genotypes for different disciplines and the DMRT3 mutation clearly influences gaits and performance in Finnhorses.
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Marcha , Caballos/genética , Condicionamiento Físico Animal , Factores de Transcripción/genética , Animales , Cruzamiento , Femenino , Frecuencia de los Genes , Genotipo , Masculino , Polimorfismo de Nucleótido Simple , Análisis de Secuencia de ADNRESUMEN
Timor ponies (TP) were first shipped to Australia in the early 1800s and were highly valued as transport and pack animals, which resulted in TPs contributing to the development of Australian horse breeds. Today, while the exact number of TPs in Australia is currently unknown, there has been recent interest in establishing a domestic breeding program for Australian TPs. The aim of this study was to evaluate the relatedness of a sample of TPs, as well as provide estimates of genomic inbreeding levels to better inform the feasibility of using these animals as founders for a domestic breeding program. Hair samples from each horse were genotyped using the Illumina 80K Infinium Equine genotyping array and data were analysed using PLINK v1.90b7, KING 2.3.2 and R v4.3.1. The results illustrate that there are distantly related and minimally inbred horses within the sampled TPs. Lengths of the ROH segments also indicated that recent inbreeding events are likely to only have occurred in a third of the horses. Overall, these results are promising for the success of a domestic TP breeding program; however, considering the low number of domestic TPs known to reside in Australia, there would certainly still be substantial benefits to incorporating additional TPs either directly from Timor or from areas in Australia that are believed to contain wild descendants of TPs.
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Endogamia , Polimorfismo de Nucleótido Simple , Caballos/genética , Animales , Indonesia , Australia , Genómica/métodosRESUMEN
Congenital heart defects (CHDs) can have profound and potentially life-threatening consequences on horses' health and performance capability. While CHDs are rare in the general horse population, the Arabian breed is disproportionately overrepresented and thus is widely suspected to be genetically predisposed. This review discusses the most common CHDs in Arabian horses, including ventricular septal defect (VSD), tetralogy of Fallot (TOF), patent duct arteriosus (PDA), tricuspid valve atresia (TVA) and atrial septal defect (ASD). This review also explores how future research into the genetic factors that likely underpin many CHDs can revolutionise the way these disorders are managed in Arabian horses.
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Pruebas Genéticas , Cardiopatías Congénitas , Enfermedades de los Caballos , Caballos , Animales , Enfermedades de los Caballos/genética , Enfermedades de los Caballos/diagnóstico , Enfermedades de los Caballos/congénito , Cardiopatías Congénitas/veterinaria , Cardiopatías Congénitas/genética , Cardiopatías Congénitas/diagnóstico , Pruebas Genéticas/veterinaria , Predisposición Genética a la EnfermedadRESUMEN
Osteochondrosis (OC) is an important skeletal disease causing profound welfare concerns in horses. Although numerous studies have explored the genetics underlying OC in various breeds, the Belgian Warmblood (BW) remains unstudied despite having a concerning prevalence of 32.0%. As a result, this study aimed to conduct genome-wide association (GWA) analyses to identify candidate variants associated with OC in BWs. To achieve this, blood samples and radiographs were collected from 407 Belgian Warmbloods registered to one of two BW studbooks (Belgisch Warmbloedpaard and Zangersheide), and genotyping was performed using the 670K Axiom Equine Genotyping Array. GWA analyses using a principle component approach were then performed on OC status (OCS; presence or absence of OC at any joint), hock OC status (HOC) and stifle OC status (SOC). These analyses yielded significantly associated (P < .01) SNPs on Equus caballus chromosome (ECA) 3, ECA 12, and ECA 18 for OCS; however, no single nucleotide polymorphisms (SNPs) reached significance for HOC or SOC. Subsequent analysis of candidate genes within 500 kilobases of the significant SNPs revealed functions broadly related to cell differentiation and chondrocyte development. While this study represents another step forward in uncovering variants and biological pathways associated with OC, additional studies are needed to validate the newly identified candidate SNPs for OC in BWs. Further studies of OC in BWs, as well as other breeds, are critical in our efforts to fully understand the disease's etiopathogenesis and ultimately provide breeding programs better equipped to improve horse health and well-being.
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Enfermedades de los Caballos , Osteocondrosis , Animales , Bélgica , Diferenciación Celular , Condrocitos/patología , Estudio de Asociación del Genoma Completo/veterinaria , Enfermedades de los Caballos/genética , Caballos/genética , Osteocondrosis/genética , Osteocondrosis/veterinariaRESUMEN
Infrared thermography (IRT) is a popular technology used for the detection of thermal changes given its non-invasive nature and lack of direct contact with the individual. Accordingly, the maximal eye temperature (MaxET) measured with IRT has been extensively applied in equine research. However, there is little information available about the potential limitations of the MaxET in field studies. Thus, the aims of this study were to 1) quantify the individual variation of MaxET in field conditions and the effects of individual, breed, body size (height at withers), eye side, sex and age, 2) determine the effects of environment and operator, and 3) explore the relationship between MaxET and rectal temperature (RT) at rest. To accomplish these aims, 791 MaxET measures from 32 horses were collected in Sweden in five different months and five farms over a period of 12 months. There was an effect of individual on IRT (P < .05) and individual MaxET varied from 29.4 to 37.6 °C. IRT was also affected (P < .05) by breed and sex (maximal difference 1.1 °C and 0.3 °C, respectively) but not by eye side, age and height at withers. There were significant effects of month and farm (maximal differences; 2.4 and 2.3 °C, respectively), between outdoor and indoor measurements (0.8 °C) and also between operators (0.2 °C). There were no correlations between MaxET and RT. These results demonstrate that in horses observed at rest in their home environment, MaxET is affected by endogenous (sex and breed) and environmental factors (farm, location and month of the year) and shows no relationship to RT. We strongly suggest that IRT technology should be used with great caution in field studies and only under conditions where these factors can be accurately accounted for.
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Temperatura Corporal , Termografía , Animales , Ojo , Caballos , Rayos Infrarrojos , Suecia , TemperaturaRESUMEN
The depletion in genetic diversity of closed-pedigree dog breeds can be a contentious topic and can lead to calls for open-registry. However, strong evidence in support of proposed open-registry solutions is lacking, with the reproductive isolation of these breeds unlikely to be the sole cause of elevated inbreeding levels. Human-induced limitations, such as popular sire effects, are unlikely to be confined to closed-registry breeds and conceivably play an important role in maintaining genetic diversity within all breeds. Consequently, the aim of the current study was to explore inbreeding levels in an open-registry breed and determine the impact open-registry has on genetic diversity. Complete pedigree records on all Australian working kelpies (AWKs) were provided by the Working Kelpie Council with the cleaned pedigree consisting of 86,671 individuals with a median pedigree depth of 6.6 generations. The average inbreeding coefficient in the AWK population was 0.049 with an increase in inbreeding coefficient of 0.0016/year. This demonstrates that opening a breed registry can have a beneficial impact on the level of inbreeding within a population over the longer-term. However, allowing for a generation length of 5.1 years yielded an effective population size of 61 for AWKs and demonstrated a pattern consistent with closed-registry dog populations of comparable size.