Genetic correlations between conformation traits and radiographic findings in the limbs of German Warmblood riding horses

Studbook inspection (SBI) data of 20 768 German Warmblood mares and radiography results (RR) data of 5102 Hanoverian Warmblood horses were used for genetic correlation analyses. The scores on a scale from 0 to 10 were given for conformation and basic quality of gaits, resulting in 14 SBI traits which were used for the correlation analyses. The radiographic findings considered included osseous fragments in fetlock (OFF) and hock joints (OFH), deforming arthropathy in hock joints (DAH) and distinct radiographic findings in the navicular bones (DNB) which were analyzed as binary traits, and radiographic appearance of the navicular bones (RNB) which was analyzed as a quasi-linear trait. Genetic parameters were estimated multivariately in linear animal models with REML using information on 24 448 horses with SBI and/or RR records. The ranges of heritability estimates were h² = 0.14–0.34 for the RR traits and h² = 0.09–0.50 for the SBI traits. Negative additive genetic correlations of r_g = -0.19 to -0.56 were estimated between OFF and conformation of front and hind limbs and walk at hand, and between DNB and hind limb conformation. There were indications of negative additive genetic correlations between DAH and all SBI traits, but because of low prevalence and low heritability of DAH, these results require further scrutiny. Positive additive genetic correlations of r_g = 0.37–0.52 were estimated between OFF and withers height and between OFH and withers height, indicating that selection for taller horses will increase disposition to develop OFF and OFH. Selection of broodmares with regards to functional conformation will assist, but cannot replace possible selection against radiographic findings in the limbs of young Warmblood riding horses, particularly with regards to OFF.     

Equestrian Coaches' Understanding and Application of Learning Theory in Horse Training

ABSTRACT

To assess the knowledge of learning theory among accredited equestrian coaches in Australia, a 20-item questionnaire was distributed to all coaches registered with the National Coaches Accreditation Scheme in Australia (n = 830). Of the 206 respondents, 79.5% considered positive reinforcement to be “very useful,” yet only 2.8% correctly explained its use in horse training. When asked about the usefulness of negative reinforcement, 19.3% of coaches considered it “very useful,” with 11.9% correctly explaining its use. Punishment was rated “very useful” by 5.2% of respondents, although only eight coaches (5.4%) explained punishment correctly. Release of pressure was considered the most effective reward for horses among respondents (78.2%). These results indicate that many equestrian coaches lack a correct understanding of positive and negative reinforcement as they apply to horse training. Given that qualified coaches play a significant role in the dissemination of information on training practices, this highlights the need for improved education of equestrian coaches. Education to remedy this situation has the potential to enhance the welfare of horses through reduced behavioral conflict and improve training outcomes.     

Variations in the timing of reinforcement as a training technique for foals (Equus caballus)

Abstract

Horses are used worldwide for a range of activities. Their usefulness and welfare in these pursuits are strongly influenced by their trainability, which may in turn be influenced by learning ability. Handling and riding horses can expose both handler and horse to a considerable risk of injury. This risk can be reduced by employing correct handling procedures that can facilitate learning in horses. As with all training, efficacy is influenced by consistency and timing. To determine the optimum timing of reinforcement, 16 unweaned naïve foals, that had previously undergone minimal human–animal interaction (i.e., not had a headcollar previously applied), of warmblood (WB; n = 6), thoroughbred (TB; n = 5) or warmblood x thoroughbred (WB x TB; n = 6) breeding were randomly assigned to three treatment groups for testing on ten training days at approximately 14-day intervals. Pressure applied to a headcollar via a lead rope was used as the stimulus for each foal to walk forward, and this was repeated until the foal had walked a distance of 8 m. The effects of three different latencies of negative reinforcement were evaluated by releasing the pressure either immediately: as the first foreleg step commenced (Treatment 1); when the second step of the forelegs was completed (Treatment 2) or when the fourth step of the forelegs was completed (Treatment 3). Each foal's rate of learning was measured by the proportion of correct responses relative to the total number of responses performed. Behavioral responses exhibited (rears, strikes, head shakes, falls, sideways movement and hops) and the steps taken over the distance were also recorded.

Initially, the foals undergoing Treatment 1 appeared to learn more quickly than those foals undergoing Treatments 2 and 3, suggesting that Treatment 1 was associated with the greatest compliance and the quickest learning. However, the foals undergoing Treatment 3 ultimately achieved significantly (p < 0.001) more correct responses, suggesting that the longer delay of reinforcement (i.e., the longer duration of aversive stimulus) may enhance learning via the negative reinforcement inherent in lead training in foals. While some conflict behaviors were shown in all treatment groups, most were exhibited on training day 2. This was reflected in the analysis of composite behaviors performed, with training days 1 and 2 being different (p < 0.001) from training day 3, and training days 1–3 being different (p < 0.001) from training days 4–10. These changes indicate that learning occurred in all treatment groups.

The foals used in this study were sired by five different stallions. While the foals sired by stallion 2 (WB) performed significantly (p < 0.001) more correct responses, those foals sired by WB stallions were significantly (p < 0.001) less likely to perform correct responses when compared with those foals of TB or WB x TB breeding. Colts were significantly (p < 0.001) more likely to perform correct responses than were fillies.     

Horse riding in urban conservation areas: Reviewing scientific evidence to guide management

Summary We undertook a literature review of the impacts of horse riding in conservation areas, and used it to guide management of horse riding in Canberra Nature Park (CNP), a large, fragmented semi‐natural park in and around the city of Canberra in the Australian Capital Territory. The literature review established that, because of their relatively large weight and small area in contact with the ground, horses have a relatively high potential for doing environmental damage. Impacts tend to be generally lowest for hikers, followed by motorcycles, horses and four‐wheeled vehicles. One study showed horse traffic caused more damage on established trails than motorcycles, off‐road bicycles or hikers. Most published studies of horse‐riding impacts in Australia have been conducted in alpine and subalpine environments, and in temperate woodlands and forests on sandstone near Sydney. They have shown that impacts are generally highest in previously untracked areas. Impacts on established trails are generally most marked on sections of trail that are wet, boggy or steep, and on unplanned and unmaintained trails. Impacts are lowest on constructed and maintained trails. Trail proliferation, associated with avoidance of untrafficable sections and short‐cutting, can be a major problem. Horses also have potential to spread weeds, because pastures and dried stock feeds contain large numbers of weed seeds that retain high levels of viability in horse manure. The risk of weed establishment is highest when manure is deposited in disturbed, damp sites, particularly when riding off‐track. Much less weed establishment is apparent when horse riders remain on‐track. Horse riding is a popular activity, but one that is relatively expensive to provide for, and one that may reduce opportunities for lower‐impact recreational park users. For all these reasons it appears socially equitable that provision is made for lower numbers of horse riders compared to numbers of park users involved in lower impact, more passive, recreational activities. We conclude by describing how this information was used to develop principles to guide management of horse riding and assess risk at individual sites in Canberra Nature Park.     

A pedigree-based study of mitochondrial D-loop DNA sequence variation among Arabian horses

Through DNA sequence comparisons of a mitochondrial D-loop hypervariable region, we investigated matrilineal diversity for Arabian horses in the United States. Sixty-two horses were tested. From published pedigrees they traced in the maternal line to 34 mares acquired primarily in the mid to late 19th century from nomadic Bedouin tribes. Compared with the reference sequence (GenBank X79547), these samples showed 27 haplotypes with altogether 31 base substitution sites within 397 bp of sequence. Based on examination of pedigrees from a random sampling of 200 horses in current studbooks of the Arabian Horse Registry of America, we estimated that this study defined the expected mtDNA haplotypes for at least 89% of Arabian horses registered in the US. The reliability of the studbook recorded maternal lineages of Arabian pedigrees was demonstrated by haplotype concordance among multiple samplings in 14 lines. Single base differences observed within two maternal lines were interpreted as representing alternative fixations of past heteroplasmy. The study also demonstrated the utility of mtDNA sequence studies to resolve historical maternity questions without access to biological material from the horses whose relationship was in question, provided that representatives of the relevant female lines were available for comparison. The data call into question the traditional assumption that Arabian horses of the same strain necessarily share a common maternal ancestry.     

The positive aspects of correct negative reinforcement

Abstract

In the scheme of contemporary animal training, horse training is virtually unique because it relies on negative reinforcement (NR) rather than positive reinforcement (PR). Furthermore, horse trainers are largely unaware that they are using NR in training. Instead, they believe in the benevolent nature of the horse and see their task in training as one of improving the balance and gymnastic ability of the horse—outcomes that emerge when the rider is similarly properly balanced. Under these conditions, it is claimed the willing horse will perform its required maneuvers. These beliefs may be associated with several welfare issues and indicate areas requiring future research: 1. The absence of release of pressure, the release of pressure at the wrong times, the use of opposing pressures simultaneously and the absence of shaping procedures are central to the development of acute and chronic stress responses in horses.

2. Resultant conflict behaviors contribute to equine wastage statistics and include behaviors that are dangerous to horses and humans.

3. There is a need for research into the mechanics of NR because it is poorly researched compared to PR.

4. When NR responses are installed correctly, only mild pressures need to be used, and results are obtained in few trials.

5. Many qualified animal trainers misunderstand NR and confuse it with punishment. They believe that PR has positive welfare implications and thus NR being “negative,” has negative welfare implications. So there is a need for horse trainers to understand learning theory and the principles that surround NR.

6. Horse trainers are isolated from advances in animal training. Therefore they increasingly seek knowledge and solutions from the growing number of “horse whisperers” and unqualified “horse psychologists.” This is potentially detrimental for the welfare of the horse and the need is urgent for universities throughout the world to become the knowledge bases for equitation science.

     

Colombian Creole horse breeds: Same origin but different diversity

In order to understand the genetic ancestry and mitochondrial DNA (mtDNA) diversity of current Colombian horse breeds we sequenced a 364-bp fragment of the mitocondrial DNA D-loop in 116 animals belonging to five Spanish horse breeds and the Colombian Paso Fino and Colombian Creole cattle horse breeds. Among Colombian horse breeds, haplogroup D had the highest frequency (53%), followed by haplogroups A (19%), C (8%) and F (6%). The higher frequency of haplogroup D in Colombian horse breeds supports the theory of an ancestral Iberian origin for these breeds. These results also indicate that different selective pressures among the Colombian breeds could explain the relatively higher genetic diversity found in the Colombian Creole cattle horse when compared with the Colombian Paso Fino.     

Genetic relationship between Mongolian and Norwegian horses?

Human populations of Central Asian origin have contributed genetic material to northern European populations. It is likely that migrating humans carried livestock to ensure food and ease transportation. Thus, eastern genes could also have dispersed to northern European livestock populations. Using microsatellite data, we here report that the essentially different genetic distances DA and (deltamu)2 and their corresponding phylogenetic trees show close associations between the Mongolian native horse and northern European horse breeds. The genetic distances between the northern European breeds and Standardbred/Thoroughbred, representing a southern-derived source of horses, were notably larger. We suggest that contribution of genetic material from eastern horses to northern European populations is likely to have occurred.     

The 24-h time budget of a takh harem stallion (Equus ferus przewalskii) pre- and post-reintroduction

Focal animal sampling was used to determine the 24-h time budget of a takh harem stallion (Equus ferus przewalskii) during the 2 weeks prior to, and the two weeks following, reintroduction into the Hustain Nuruu Steppe Reserve, Mongolia. Both before and after release, the stallion spent approximately 47% of his time grazing, 6% standing, and 5% in recumbent rest. The biggest changes to the time budget after release were a 4-fold increase in the amount of time spent moving, and a 50% decrease in the amount of time spent resting in a standing position. During the middle of the day when the temperatures were hottest, the stallion exhibited less grazing and more standing resting behaviour than in the morning or evening hours. Recumbent rest invariably occurred in the hours before dawn.     

Refinement of a quantitative trait locus on equine chromosome 5 responsible for fetlock osteochondrosis in Hanoverian warmblood horses

In this report, we provide 29 new informative microsatellites distributed over a region of 21 Mb on horse chromosome (ECA) 5 and refine a quantitative trait locus (QTL) for fetlock osteochondrosis dissecans (OCD) to a genome-wide significant interval between 78.03 and 90.23 Mb on ECA5. Genotyping was performed in 211 Hanoverian warmblood horses from 14 paternal half-sib groups. Within this OCD-QTL, collagen type XXIV alpha 1 was identified as a potential functional candidate gene for equine osteochondrosis. This report is a further step towards unravelling the genes that cause equine osteochondrosis.     

Horse domestication and conservation genetics of Przewalski's horse inferred from sex chromosomal and autosomal sequences

Despite their ability to interbreed and produce fertile offspring,there is continued disagreement about the genetic relationshipof the domestic horse (Equus caballus) to its endangered wildrelative, Przewalski's horse (Equus przewalskii). Analyses havediffered as to whether or not Przewalski's horse is placed phylogeneticallyas a separate sister group to domestic horses. Because Przewalski'shorse and domestic horse are so closely related, genetic datacan also be used to infer domestication-specific differencesbetween the two. To investigate the genetic relationship ofPrzewalski's horse to the domestic horse and to address whetherevolution of the domestic horse is driven by males or females,five homologous introns (a total of 3 kb) were sequenced onthe X and Y chromosomes in two Przewalski's horses and threebreeds of domestic horses: Arabian horse, Mongolian domestichorse, and Dartmoor pony. Five autosomal introns (a total of6 kb) were sequenced for these horses as well. The sequencesof sex chromosomal and autosomal introns were used to determinenucleotide diversity and the forces driving evolution in thesespecies. As a result, X chromosomal and autosomal data do notplace Przewalski's horses in a separate clade within phylogenetictrees for horses, suggesting a close relationship between domesticand Przewalski's horses. It was also found that there was alack of nucleotide diversity on the Y chromosome and highernucleotide diversity than expected on the X chromosome in domestichorses as compared with the Y chromosome and autosomes. Thissupports the hypothesis that very few male horses along withnumerous female horses founded the various domestic horse breeds.Patterns of nucleotide diversity among different types of chromosomeswere distinct for Przewalski's in contrast to domestic horses,supporting unique evolutionary histories of the two species.