Search Results (361)

Speed is not only the primary objective of racehorse breeding but also a crucial indicator for evaluating racehorse performance. This study investigates a newly developed racehorse breed in China. Through whole-genome resequencing, we selected 60 offspring obtained from the crossbreeding of Thoroughbred horses and Xilingol horses for this study. This breed is tentatively named “Grassland-Thoroughbred”, and the samples were divided into two groups based on racing ability: 30 racehorses and 30 non-racehorses. Based on whole-genome sequencing data, the study achieved an average sequencing depth of 25.63×. The analysis revealed strong selection pressure on chromosomes (Chr) 1 and 3. Selection signals were detected using methods such as the nucleotide diversity ratio (π ratio), integrated haplotype score (iHS), fixation index (Fst), and cross-population extended haplotype homozygosity (XP-EHH). Regions ranked in the top 5% by at least three methods were designated as candidate regions. This approach detected 215 candidate genes. Additionally, the Fst method was employed to detect Indels, and the top 1% regions detected were considered candidate regions, covering 661 candidate genes. Functional enrichment analysis of the candidate genes suggests that pathways related to immune regulation, neural signal transmission, muscle contraction, and energy metabolism may significantly influence differences in performance. Among these identified genes, PPARGC1A, FOXO1, SGCD, FOXP2, PRKG1, SLC25A15, CKMT2, and TRAP1 play crucial roles in muscle function, metabolism, sensory perception, and neurobiology, indicating their key significance in shaping racehorse phenotypes. This study not only enhances understanding of the molecular mechanisms underlying racehorse speed but also provides essential theoretical and practical references for the molecular breeding of Grassland-Thoroughbreds. Full article

The aim of this retrospective clinical study was to assess surgical duration and surgical and post-operative complications associated with Video-Assisted Thoracoscopic Surgery (VATS) and lung biopsy in horses with severe Equine Pasture Asthma (EPA) and paired control horses. Twelve horses (6 EPA-affected, 6 control) were sex, age and breed matched. Twenty-four thoracic surgeries were performed. Surgery of each matched pair (EPA-affected and healthy) was performed during asthma exacerbation (summer) and remission (winter). Surgical times were shorter with uncomplicated thoracoscopy (85 min) and significantly longer (p < 0.001) when intra-operative complications necessitated conversion to thoracotomy (156 min). The overall surgical time of EPA-affected horses during asthma exacerbation was significantly longer than control horses at any time point, predicted mean difference of 78 min (p < 0.05). When comparing EPA-affected horses to themselves during asthma exacerbation and remission, surgical times were significantly longer (p < 0.01) with a predicted mean difference of 98 min; this effect of seasonality did not occur amongst control horses. Intra-operative surgical complications (6/24) were evenly divided between EPA and control horses, however, only severe EPA horses in exacerbation were noted to have lung hyperinflation. Post-operative complications: fever, colic, hemothorax, pneumothorax, subcutaneous emphysema, surgical site infection, and/or laminitis occurred in 13/24 surgical procedures (54%). No fatalities resulted from these procedures. Full article

This study examines the associations between linearly scored phenotypic traits and auction sales prices of young event horses in Ireland, aiming to identify key traits influencing market value. Data from 307 horses sold at public auctions (2022–2023) were analysed using regression analysis, binary optimisation, and Principal Component Analysis (PCA). Regression identified Head–neck Connection, Quality of Legs, Walk length of Stride, and Scope as highly significant predictors of sales price (p < 0.001), with Length of Croup, Trot Elasticity, Trot Balance, and Take-off Direction also significant (p < 0.05). Optimised regression reduced the number of relevant traits from 37 to 8, streamlining evaluation. PCA highlighted eight principal traits, including Scope, Elasticity, and Canter Impulsion, explaining 61.19% of variance in the first four components. These results demonstrate that specific conformation, movement, and athleticism traits significantly affect auction outcomes. The findings provide actionable insights for breeders and stakeholders, suggesting that targeted selection for high-impact traits could accelerate genetic progress and improve market returns. Furthermore, these traits could underpin the development of economic or buyer indices to enhance valuation accuracy and transparency, with potential application across equestrian disciplines to align breeding objectives with market demands. Full article

The core objective of racehorse breeding is to enhance the speed and endurance of the horses. The Grassland-Thoroughbred is an emerging horse breed developed in northern China in recent years, characterized by excellent speed performance, enduring stamina, and strong environmental adaptability. However, research on the genetic characteristics within this breed and the genes associated with athletic performance remains relatively limited. We conducted whole-genome resequencing of Grassland-Thoroughbred F1, F2, F3, and the crossbred population (CY) and obtained a total of 4056.23 Gb of high-quality data after quality control. The single nucleotide polymorphisms (SNPs) were primarily distributed in intergenic regions, followed by intronic regions. Principal component analysis (PCA) and STRUCTURE revealed clear distinctions among the generations, with a notable overlap between CY and F3. Using the SNP dataset, we analyzed the number and length distribution patterns of runs of homozygosity (ROHs) in the genomes of different generational groups of Grassland-Thoroughbreds. Short ROHs ranging from 0.5 to 2 Mb were the most abundant, with the following distribution: F1 (85.15%) > F2 (82.92%) > CY (78.75%) > F3 (77.51%). Medium-length ROHs (2–8 Mb) and long ROHs (>8 Mb) together exhibited a similar but opposite trend. The average length of ROHs was 1.57 Mb. The inbreeding coefficients (F_ROH) among different generational groups of Grassland-Thoroughbreds were as follows: F1 (0.0942) < F2 (0.1197) < CY (0.1435) < F3 (0.1497). Through ROH island analysis, 10 high-frequency ROH regions were identified and annotated with 120 genes. Genomic regions and candidate genes associated with athletic traits—ACAD8, OPCML, PRDX2, NTM, NDUFB7, SCL25A15, FOXO1, and SLC4A10—were identified. These genes may play important roles in regulating muscle performance, mitochondrial energy supply, and learning and memory processes in horses and are closely associated with the athletic ability of the Grassland-Thoroughbred population. This study is the first to systematically characterize the genomic diversity and inbreeding dynamics of the Grassland-Thoroughbred during the breeding process. It identifies candidate genes that may influence athletic performance, thereby providing an important molecular foundation and theoretical basis for the genetic improvement and performance-based selection of this emerging breed. Full article

To date, serum biochemical analytes reference intervals (RIs) in Lusitano horses have not been studied. This study aimed to establish the RIs for biochemical analytes following the American Society of Veterinary Clinical Pathology guidelines and to compare them with the general equine population’s RIs. Blood samples were collected from 76 clinically healthy adult Lusitano horses, and RIs of 22 biochemical variables were determined using Reference Value Advisor software. Lusitano horse-specific RIs are proposed for the following variables: total protein (3.9–7.0 g/dL), albumin (2.5–3.8 g/dL), globulin (1.1–3.7 g/dL), total bilirubin (1.0–5.6 mg/dL), direct bilirubin (0.09–0.68 mg/dL), indirect bilirubin (0.7–5.2 mg/dL), urea (21.0–38.9 mg/dL), creatinine (0.9–2.0 mg/dL), aspartate aminotransferase (150.7–345.1 IU/L), alkaline phosphatase (60.7–227.4 IU/L), lactate dehydrogenase (247.6–959.0 IU/L), glucose (75.5–131.5 mg/dL), cholesterol (58.6–125.2 mg/dL), sodium (129.0–154.9 mmol/L), phosphorus (1.8–4.5 mmol/L), chloride (90.3–107.0 mmol/L), and calcium (8.9–12.6 mg/dL). Different RIs were identified for healthy adult Lusitano horses for 17/22 serum biochemical analytes tested, emphasizing the need for breed-specific RIs to prevent misinterpretation of laboratory results. Full article

Gastrointestinal parasitic diseases pose significant health risks to equine populations. This study investigated the epidemiological patterns of equine gastrointestinal parasites in Xinjiang by analyzing 83 fecal samples collected from Ili (n = 62) and Urumqi (n = 21) between August and November 2024. The modified McMaster technique was employed to quantify fecal egg counts (EPG) and was complemented by morphological identification to assess infection dynamics related to geography, breed specificity, and management practices. The results demonstrated an overall infection prevalence of 66.3% (55/83), with strongyles, Parascaris equorum, and Eimeria oocysts being present. Significant geographical variation was observed, with Ili exhibiting a higher prevalence (74.2%) compared to Urumqi (42.9%). Breed susceptibility analysis revealed that there was a 94.1% prevalence in Yili horses versus 42.9% in Kazakh horses. Pasture-managed herds showed markedly higher infection rates (94.1%) than stable-based systems (50.0%). Parasite community composition was dominated by strongyles (82.1%), followed by Triodontophorus spp. (27.7%) and P. equorum (2.4%). These findings highlight severe parasitic infection risks in Xinjiang’s grazing equids, underscoring the urgency of implementing targeted anthelmintic protocols to mitigate disease transmission. Full article

Background: The reproductive ability of equine species is a critical component of equine breeding programs, with sperm quality serving as a primary determinant of reproductive success. In this study, we perform an integrative analysis of proteomics and metabolomics in seminal plasma to identify proteins and metabolites associated with sperm quality and reproductive ability in equine species. Methods: We utilized the CEROS instrument to assess the morphology and motility of sperm samples from three horses and three donkeys. Additionally, we statistically analyzed the mating frequency and pregnancy rates in both species. Meanwhile, the 4D-DIA high-throughput proteomic and metabolomic profiling of seminal plasma samples from horses and donkeys revealed a complex landscape of proteins and metabolites. Results: Our findings reveal a certain degree of correlation between seminal plasma proteins and metabolites and sperm quality, as well as overall fertility. Notably, we found that the proteins B3GAT3, XYLT2, CHST14, HS2ST1, GLCE, and HSPG2 in the glycosaminoglycan biosynthesis signaling pathway; the metabolites D-glucose, 4-phosphopantetheine, and 4-hydroxyphenylpyruvic acid in the tyrosine metabolism, starch, and source metabolisms; and pantothenate CoA biosynthesis metabolism present unique characteristics in the seminal plasma of equine species. Conclusions: This comprehensive approach provides new insights into the molecular mechanisms underlying sperm quality and has identified potential proteins and metabolites that could be used to indicate reproduction ability. The findings from this study could be instrumental in developing novel strategies to enhance equine breeding practices and reproductive management. Future research will focus on exploring their potential for clinical application in the equine industry. Full article

Diptera-borne diseases pose a major threat to global health, and their distribution is constantly changing due to climate change, globalization, and environmental changes. To improve the knowledge of dipteran species and their distribution in equine facilities, CDC-UV and oviposition traps were placed, and the dipping technique was performed in 16 equestrian centers of Northwest (NW) Spain (Galicia and Castilla y León Autonomous Communities) between July and November 2023. A questionnaire was distributed among the horse owners to obtain additional information. Four genera of culicids, Culex (51.8%), Culiseta (38.6%), Anopheles (8.4%), and Aedes/Ochlerotatus (1.2%) were identified in the equestrian centers. Culex pipiens s.l. was the most prevalent and well-distributed species (93.8% of the centers), whereas Anopheles maculipennis s.l. and An. claviger/petragnani, the anopheline species, were the most frequent (37.5% and 31.2%, respectively). The Culiseta genus was found in approximately 81.2% of the equine facilities. All genera were collected at medium and high altitudes and in Csb (warm-summer Mediterranean climate) areas. Equestrian centers from NW Spain albeit a variety of culicids with high vectorial capacity, together with an ideal environment for their breeding, the presence of vectors and hosts (humans and animals). This potential problem for global health enhances the need for entomological surveillance. Full article

This study aimed to determine the prevalence of antibodies against equine brucellosis in three distinct equid groups (farm animal, urban carthorse, and sport horse) in Western Pará, Brazil, and to identify associated risk factors. A cross-sectional study, involving 75 farms across 14 municipalities, sampled 1069 equids composed of urban carthorses and sport horses. Serum samples were tested for antibodies against Brucella spp. using the buffered acidified plate antigen (BAPA) test for screening, followed by the serum agglutination in tubes with 2-mercaptoethanol (2-ME) for confirmation. Univariate and multivariate analyses assessed associations between brucellosis and potential risk factors. Out of the 1059 equids sampled, 4.05% (95% CI: 3–5.5%) tested positive in the BAPA test. Of the 44 BAPA-positive samples, 11 were confirmed positive by 2-ME, 15 were inconclusive, and 18 were negative, yielding an animal-level prevalence of 1.03% (95% CI: 0.5–1.8%) for equine brucellosis in western Pará. Prevalence was higher in the Southwest Pará Mesoregion (p = 0.047) compared to the Lower Amazon Mesoregion. No significant associations were found with animal type, reproductive problems, animal sex, species, breed, and age group. Out of the 75 farms, 8 (10.66%) had at least one seropositive equid. Confirmed cases were identified in five municipalities (Brasil Novo, Uruará, Altamira, Rurópolis, and Itaituba). This first report of equine brucellosis in Western Pará underscores the need for enhanced surveillance and control measures to mitigate its zoonotic risk to humans and transmission to other animals. Full article

The Hucul horse is a Polish primitive breed with a small population size, which highlights the importance of preserving the genetic resources. The cryopreservation of semen is essential for creating gene banks, but its effect on the acrosome reaction in Hucul stallions has not yet been investigated. The acrosome reaction is one of the most important physiological events associated with the fertilization process. Therefore, our goal was to determine the level of acrosome reaction in chilled and frozen/thawed Hucul stallion semen using the FluoAcro test and the SCA^® semen analysis system. We found that semen cryopreservation significantly reduced sperm motility and was associated with an increased percentage of acrosome-reacted spermatozoa. It should be noted, however, that, in this case, there was no negative control, and the results may reflect acrosomal damage rather than the elicited responses. Further validation of the methods with equine sperm and the inclusion of a control are recommended. Full article

Local horse breeds, particularly cold-blood types, are often marginalized in economic and social contexts, primarily due to the neglect of their economic, genetic, and cultural potential, as well as their role in preserving the identity of rural areas, local communities, and ecosystems. The valorization of these breeds is a crucial prerequisite for their economic repositioning. The Croatian Posavina horse is a local breed, well adapted to harsh, extensive production systems. Its sustainability is achieved through pasture-based meat production, primarily targeting foreign European markets. Ensuring the sustainability of conservation programs requires a thorough understanding of growth dynamics, carcass traits, and meat quality. This study assessed growth performance and carcass characteristics in a sample of 30 male foals, with ten animals selected for detailed analysis of fatty acid, amino acid, and volatile aromatic compound profiles. At eleven months of age, the foals reached a live weight of 347 kg and a dressing percentage of 60.62%. Color, tenderness, and water-holding capacity parameters were favorable for consumers. The meat’s high protein content (22.37%) and low intramuscular fat (3.61%) make it suitable for health-conscious or sensitive consumer groups. A high proportion of polyunsaturated fatty acids (28.5%) and a nutritionally balanced ω-6/ω-3 ratio (3.46) highlight the meat’s functional properties. The essential-to-non-essential amino acid ratio (0.81) further supports its nutritional value. Sensory analysis confirmed an attractive appearance, desirable texture and flavor, and a rich aromatic profile. The carcass and meat quality results, when compared with the production traits of other horse breeds, indicate that Croatian Posavina foal meat is a high-quality and nutritionally valuable alternative to conventional red meat. With optimized conservation and production strategies, the Croatian Posavina horse holds strong potential for market repositioning within sustainable and functional meat production systems. Full article

Background/Objectives: Standardbreds, a breed of horses used in harness racing at either the trot or the pace, established a closed studbook in 1973. Concerns about genetic diversity within the breed led the United States Trotting Association (USTA) to establish a limit of mares bred per stallion (i.e., a studbook cap) in 2009. Here, we aimed to evaluate the impact of the breeding restrictions on genetic diversity between and among subpopulations. Methods: Sixteen short tandem repeats (STRs) were analyzed across a dataset of 176,424 Standardbreds foaled in the United States between 1998 and 2021. We examined allelic richness (Na), number of effective alleles (Ne), expected heterozygosity (H_E), observed heterozygosity (H_O), inbreeding coefficient (F_IS), and fixation index (F_ST) across 24 years, differentiating by gate type, and comparing pre-(1998–2009) and post-(2010–2021) studbook cap periods using regression analysis. Results: Our results support decreased genetic diversity for both trotters and pacers over time. However, pacing Standardbreds exhibited significantly slower rates of decrease in genetic diversity after the 2009 studbook cap, as evidenced by Ne, H_E, and F_IS (P_Bonferroni < 0.01). Additionally, moderate levels of genetic differentiation were found between trotters and pacers (0.05 < F_ST < 0.09), which increased over time. Conclusions: Given that the rate of loss of diversity does not appear to differ pre and post studbook cap in trotters and that there is an increase in genetic differentiation between the groups over time, developing additional breeding tools and strategies is necessary to help the subpopulation mitigate further decline. Full article

Autosomal trisomy, a genetic disorder characterized by the presence of an extra autosome, is a rare but important chromosomal abnormality in horses, often associated with infertility, developmental abnormalities, and reduced life expectancy. This study represents the largest population-level screening for autosomal trisomy in horses; the analysis used single nucleotide polymorphism (SNP) panel genotype intensity data from 17,078 horses, 6601 of which were juveniles (i.e., ≤12 months of age) when genotyped. Using methodologies adapted from similar screening studies in cattle, the only aneuploidy detected was trisomy 27 in two juvenile male Irish Sport Horses (ISH) (0.03% prevalence among juveniles or 0.01% prevalence in the overall population). One ISH colt was cytogenetically confirmed and displayed no overt external phenotypic abnormalities, while cytogenetics was not undertaken on the other ISH colt, nor was it phenotypically assessed. Parentage analysis revealed that one ISH colt inherited two different copies of chr27 from the sire, demonstrating heterodisomy, likely due to a nondisjunction event during meiosis I in the sire. The other ISH colt inherited two different copies of chr27 from the dam, also indicating heterodisomy; the dam was 23 years of age when the colt was born. Based on the observed prevalence of autosomal trisomy, it can be estimated that at least 3 foals per 10,000 live births are likely to have autosomal trisomy. Though, given that only 74 (i.e., 0.004%) of horses were genotyped within a month of birth, this is likely an underestimate. The economic consequence of undiagnosed trisomy in high-value breeding horses that are potentially infertile could be substantial. As horse genotyping for parentage verification and discovery is transitioning to medium-density single nucleotide polymorphism panels, routine genomic screening for autosomal aneuploidy could be readily undertaken and potentially should form a standard screening prerequisite along with other genetic defects at horse sales. Currently, thoroughbred horses registered for racing are not genotyped, and only a limited number of sport horse studbooks are using SNP genotyping. This highlights an opportunity for those already genotyping to expand their support for breeders through low-cost, high-value chromosomal screening at the time of registration rather than incurring additional costs over the horse’s life cycle to determine the root cause of certain phenotypes owing to the undiagnosed trisomy. Full article

This study aimed to evaluate the chemical composition of milk from Kazakh mares kept under free-grazing conditions on natural pasture without supplementary feeding. Fifty Kazakh mares were aged 3 to 13 years, kept in herds, and categorized by age, number of foalings, and lactation stage for statistical analysis. Milk samples were collected, chilled, and analyzed on the same day using a Milkoscan FT2. The composition of fat, protein, lactose, total solids, casein, and other components was examined. Statistical analyses, including ANOVA, PCA, CDA, and Pearson correlation analysis, were performed using JMP 17 Pro to assess the effects of lactation stage, mare age, and foaling number and to identify key relationships. The results showed that milk composition was significantly influenced by these factors. Milk from the late-lactation stage contained higher protein, lactose, and total nutrients, while milk from the early-lactation stage had a higher sugar content and acidity. Older mares and those with higher foalings produced milk with higher concentrations of glucose and galactose, while younger mares and those with fewer foalings produced milk with higher fat. A key aspect of this experiment was that all mares grazed exclusively on natural pastures without supplementation, allowing for an objective assessment of their inherent productive potential. These findings deepen the understanding of mare milk composition dynamics in Kazakh breed horses under extensive management, supporting its potential for organic dairy production. Full article

Breed bias exists within many of the top disciplines of equestrian sport. Therefore, the objective of this study was to evaluate the influence of breed on performance at the CCI5*-L level of eventing. To do so, the results of all CCI5*-L events from 2014 to 2024 were assessed. Initially, Thoroughbreds were compared to all non-Thoroughbreds, and this was followed by assessing the ten primary breeds. Data included penalties accrued in dressage, cross country, show jumping, and overall. Additionally, the likelihood of completing each phase was assessed. It was found that Thoroughbreds accrued more dressage penalties than non-Thoroughbreds (p < 0.001). When comparing primary breeds, Thoroughbreds were found to accumulate more dressage penalties than Hannoverian, Irish Sport Horse, Dutch Warmblood, Oldenburg, and Selle Francais (p < 0.03). When assessing cross-country, Thoroughbreds were more likely to finish without fault when compared to non-Thoroughbreds (p < 0.001). Non-Thoroughbreds were more likely to show jump without fault (p < 0.001), while Thoroughbred were found to have higher overall show jumping penalties in comparison to Anglo-European Studbook, Holsteiner, Irish Sport Horse, Dutch Warmblood, Oldenburg, and Selle Francais (p = 0.01). When evaluating overall penalties accumulated throughout the event, there was no effect of breed (p = 0.42). Overall, there was no advantage in competing a non-Thoroughbred in comparison to a Thoroughbred when considering total penalties accrued, indicating a level playing field within competition. Therefore, breed bias against TBs should be negated when selecting for CCI5*-L eventing prospects. Full article