With the increasing development of genetic testing and advanced genomic technologies, horse owners and breeders have more opportunities than ever before to learn more about the genetic background of ...their horses. This publication provides information to help horse owners and breeders understand what genetic testing services are, which genetic tests are available for their horses, and how to locate genetic testing services. Written by Julia L. Ciosek, Carissa Wickens, and Samantha A. Brooks, and published by the Veterinary Medicine—Department of Large Animal Clinical Sciences, UF/IFAS Extension, April 2024.
Knowledge about horses and horse breeding is a cultural asset, which has evolved over centuries. At the same time, it is an essential economic commodity. The anthropological focus on knowledge of ...this study is on the current parameters of breeding the “Hannoveraner”, one of the world’s largest and also most popular horse breeds. The author conducts participatory observations on agricultural family farms that breed them and follows the development of individual horses from birth to successful athletes. The aim is to identify the genesis and exchange of the various stocks and forms of knowledge. The guiding questions of the analysis are: What is equine knowledge and how is it currently changing? Equine knowledge accumulates between breeders and horses and the diverse other actors and entities of this multispecies constellation in their shared everyday life. Videographic vignettes and photographs open up further access to the, primarily incorporated, knowledges and practices of horse breeding in agricultural environments, which are at the center of the ethnography.
•The population does not exhibit serious factors that affect genetic variability.•It is necessary to implement a genetic management program seeking to maximize genetic variability and especially ...conserve the structure of the Mangalarga Marchador breed as a well-defined genetic entity differentiated from other horse breeds.
Mangalarga Marchador (MM) is the most important Brazilian horse breed, with 600 thousand animals registered. The aim of this study carry out the genetic characterization of the breed. Samples were collected from 355 horses MM, n = 218; Andalusian n = 20; Purebred Lusitano n = 21; Sorraia (SOR) n = 16; Thoroughbred n = 21; Campolina (CAM) n = 21, and Mangalarga (MAN) n = 38 and genotyped with the SNP 70K BeadChip. Parameters were calculated, such as expected heterozygosities (He), Hardy-Weinberg equilibrium (HWE), linkage disequilibrium (r2), genetic differentiation, and principal component analysis (PCA); and haplotypes in common and population structure was assessed by Bayesian methods. The MM breed obtained reasonable He and deviations from HWE. The SOR breed had high r2, and CAM and MM had low r2. MAN and MM had a similar haplotype block. Analyses of population structure showed that, just as the other Brazilian breeds, the MM breed is not well defined, showing signs of substructure and possibly admixture. The analyses with PCA showed that Brazilian breeds clustered together, and well separated from the remaining breeds. A breeding program seeking to maximize the variability of MM and structure the breed as a more defined genetic entity should be implemented immediately.
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Polish Konik remains one of the most important horse breeds in Poland. The primitive, native horses with a stocky body and mouse-like coat color are protected by a conservation program, while their ...Polish population consists of about 3,480 individuals, representing 16 dam and six sire lines. To define the population’s genetic structure, mitochondrial DNA and Y chromosome sequence variables were identified. The mtDNA whole hypervariable region analysis was carried out using the Sanger sequencing method on 233 Polish Koniks belonging to all dam lines, while the Y chromosome analysis was performed with the competitive allele-specific PCR genotyping method on 36 horses belonging to all sire lines. The analysis of the mtDNA hypervariable region detected 47 SNPs, which assigned all tested horses to 43 haplotypes. Most dam lines presented more than one haplotype; however, five dam lines were represented by only one haplotype. The haplotypes were classified into six (A, B, E, J, G, R) recognized mtDNA haplogroups, with most horses belonging to haplogroup A, common among Asian horse populations. Y chromosome analysis allocated Polish Koniks in the Crown group, condensing all modern horse breeds, and divided them into three haplotypes clustering with coldblood breeds (28 horses), warmblood breeds (two horses), and Duelmener Pony (six horses). The clustering of all Wicek sire line stallions with Duelmener horses may suggest a historical relationship between the breeds. Additionally, both mtDNA and Y chromosome sequence variability results indicate crossbreeding before the studbooks closure or irregularities in the pedigrees occurred before the DNA testing introduction.
The effect of steroid hormones on the quality of fresh and cryopreserve sperm has not been fully understood. This study aimed to evaluate the effect of testosterone, dihydrotestosterone, estradiol, ...and cortisol on the quality of fresh and cryopreserved stallion sperm. The study was conducted on 40 Equus caballus stallions, including Arab (n=20), Oryol trotting (n=4), Standardbred (n=4), and Soviet Heavy Draft (n=12) breeds. The average age of the experimental animals was 9.9 ± 0.7 years. We determined standard quality indicators in fresh and cryopreserved sperm and the concentration of steroid hormones in the blood plasma of stallions. Results of the study suggested a negative correlation between the level of testosterone with total (r=-0.41; p<0.01) and progressive (r=-0.44; p<0.01) sperm motility in cryopreserved sperm as well as in fresh sperm (r=-0.38; p<0.05 and r=-0.39; p<0.05 correspondingly). While the level of estradiol showed a positive correlation with survival rate in cryopreserved (r=0.35; p<0.05) and in fresh (r=0.33; p<0.05) sperm. Further, the level of cortisol in the blood plasma of stallions did not show any statistically significant correlations with the qualitative characteristics of sperm. A positive relationship was found between the concentration of dihydrotestosterone with the volume of ejaculate (r=0.37; p<0.05) and the total number of sperm in the ejaculate (r=0.43; p<0.01). Results of the study can be concluded that steroid hormones have different effects on the quality indicators of fresh and cryopreserved sperm of stallions and their concentration in the blood should be considered when selecting stallions for cryopreservation of sperm.
Simple Summary: The disease osteochondrosis dissecans (OCD) is an important health-related trait in horse breeding. This study aimed at finding a breeding strategy to reduce the occurrence of OCD ...without affecting the riding horse performance traits substantially. Therefore, a lifelike simulation of different possible ways to include this trait in a horse breeding program was performed. Effective strategies can be the exclusion of affected animals from breeding as well as the selection based on a breeding value estimation which considered OCD susceptibility together with riding horse performance traits in an index. A reduction in the frequency of occurrence of OCD was found to be linked with a slight decrease in the breeding values for the riding horse characteristics.
We hypothesized that thiols and particularly glutathione (GSH) are essential for the regulation of stallion sperm functionality. To test this hypothesis, we initially investigated the relationship ...between sperm function and GSH content, revealing highly significant correlations between GSH, sperm viability, motility, and velocity parameters (P < 0.001). Furthermore, the deleterious effects of GSH depletion using menadione and 1,3 dimethoxy 1,4, naphtoquinone (DMNQ) were able to be prevented by the addition of cysteine, but no other antioxidant. Pre-incubation with cysteine prevented menadione and DMNQ induced damage to sperm membranes after 1 h (P < 0.001; P < 0.05) and after 3 h of incubation (P < 0.001, P < 0.05). Pre-incubation with cysteine ameliorated both the menadione- and DMNQ-induced increase in 4-hydroxynonenal (P < 0.001). As cysteine is a precursor of GSH, we hypothesized that stallion spermatozoa are able to synthesize this tripeptide using exogenous cysteine. To test this hypothesis, we investigated the presence of two enzymes required to synthesize GSH (GSH and GCLC) and using western blotting and immunocytochemistry we detected both enzymes in stallion spermatozoa. The inhibition of GCLC reduced the recovery of GSH by addition of cysteine after depletion, suggesting that stallion spermatozoa may use exogenous cysteine to regulate GSH. Other findings supporting this hypothesis were changes in sperm functionality after BSO treatment and changes in GSH and GSSG validated using HPLC-MS, showing that BSO prevented the increase in GSH in the presence of cysteine, although important stallion to stallion variability occurred and suggested differences in expression of glutamate cysteine ligase. Mean concentration of GSH in stallion spermatozoa was 8.2 ± 2.1 µM/109 spermatozoa, well above the nanomolar ranges per billion spermatozoa reported for other mammals. Summary Sentence Thiols regulate stallion sperm functionality.
The aim was to assess the efficiency of gaits characteristics in improving jumping performance of sport horses and confront accelerometers and judge scores for this purpose. A sample of 1,477 young ...jumping horses were measured using accelerometers for walk, trot, and canter. Of these, 702 were genotyped with 541,175 SNPs after quality control. Dataset of 26,914 horses scored by judges in breeding shows for gaits and dataset of 142,682 horses that performed in jumping competitions were used. Analysis of accelerometric data defined three principal components from 64% to 89% of variability explained for each gait. Animal mixed models were used to estimate genetic parameters with the inclusion to up 308,105 ancestors for the relationship matrix. Fixed effects for the accelerometric variables included velocity, gender, age, and event. A GWAS was performed on residuals with the fixed effect of each SNP. The GWAS did not reveal other QTLs for gait traits than the one related to the height at withers. The accelerometric principal components were highly heritable for the one linked to stride frequency and dorsoventral displacement at trot (0.53) and canter (0.41) and moderately for the one linked to longitudinal activities (0.33 for trot, 0.19 for canter). Low heritabilities were found for the walk traits. The genetic correlations of the accelerometric principal components with the jumping competition were essentially nil, except for a negative correlation with longitudinal activity at canter (-0.19). The genetic correlation between the judges' scores and the jumping competition reached 0.45 for canter (0.31 for trot and 0.17 for walk). But these correlations turned negative when the scores were corrected for the known parental breeding value for competition at the time of the judging. In conclusion, gait traits were not helpful to select for jumping performances. Different gaits may be suitable for a good jumping horse.
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