French Trotters Research Articles

Insight into the genetic diversity of Selle Français horse populations based on whole D-loop sequencing of mitochondrial DNA

The Selle Français (SF) breed originated from native France horses crossed with Thoroughbreds, Arabs, Anglo-Arabs and French Trotters, which allowed for individuals to be obtained with excellent predispositions and a versatile usage for equestrian sports. The performance of the SF horse is widely accepted in the fields of show jumping and eventing; however, they have successfully started to compete in other areas such as dressage, vaulting, carriage driving and TREC competitions. To date, information about the genetic structure of the SF breed has been very limited. In the present report, Sanger sequencing was applied to analyse the whole D-loop of mitochondrial DNA of 98 samples representing Selle Français horses originating from two populations: Algerian (n=47) and French (n=51). The result obtained showed the presence of 19 SNPs, which allowed us to divide the samples into 41 haplotypes (OR909723‐OR909773). A higher number of haplotypes was detected in the Algerian population (n=24) compared to the French population (n=14), but both populations did not represent unique clusters and showed a high degree of genetic similarities. The result showed that the identified haplotypes of the SF belonged to four clades: L, A, B and G. The present report gives strong evidence that the Selle Français breed has been established based on a great influence of the Thoroughbred, whose close connection is more visible in the French population. The haplogroup assignment to L clades proved that the SF breed has European origin as ancestral haplogroup L was assigned to West and South Europe while A to West Asia and G and B to Middle East. Our results show SF as an example of a contemporary breed of sport horses with European roots further influenced by local breeds.

The genetic basis of the sperm quality of stallions

One of the important factors affecting the reproductive function is the genotype of the animal. The method of genomic selection is based on the use of polymorphic single nucleotide substitutions (SNP) as markers for determining the value of the genotype of an animal or plant. The formation and functioning of the reproductive system of animals occurs as a result of the coordinated interaction of a wide range of genes. The search for genomic associations of GWAS (Genome-Wide Association Studies) with signs of fertility will allow further selection of animals based on these indicators at the genomic level. Sperm was obtained with the help of mares in hunting and on a phantom using an artificial Hannover vagina (Minitube, Germany). The sperm of each stallion was collected at least three times. The semen quality of 96 stallions of different breeds (Arabian, Akhal-Teke, Trakenen, thoroughbred horse, Oryol trotter, French trotter, Soviet heavy horse, Shetland pony, Welsh pony, horses of different breeds) was analyzed. High variability of sperm quality indicators was revealed. For example, the concentration of sperm in the ejaculate varied from 59 to 514 million /ml, progressive mobility from 20 to 87%, and the number of cells without damage from 21.6 to 95.6%. Such variability of the studied features makes it possible to assume that their formation in the process of ontogenesis occurs under the influence of genetic factors. The GWAS analysis of ejaculate volume, concentration and motility of stallion sperm revealed potential candidate genes associated with these indicators. The associations identified in our study are promising candidates for further identification of the biological mechanisms underlying the quality of stallion sperm.

Effect of high-starch or high-fibre diets on the energy metabolism and physical performance of horses during an 8-week training period.

Large amounts of high-starch concentrates are traditionally fed to horses in training. However, this has been associated with digestive or muscle diseases and behavioural modifications. In parallel, it has been demonstrated that horses fed high-fibre, low-starch diets achieve the same performance over an exercise test as the ones fed high-starch diets. However, whether the same performance level can be maintained over a longer training cycle is still being determined. This study aimed to compare the evolution in physical performance and cardiorespiratory responses of two groups of French Trotters fed either a control high-starch (15.0g dry matter hay/kg body mass/day + 6.6g dry matter oats/kg body mass/day) or a high-fibre diet (75% of oats replaced by dehydrated alfalfa) over an 8-week training period. The horses that entered the trial were untrained for ≥4months and previously fed hay only. Track training with speed monitoring included interval training sessions and 2400m performance tests from week 1 to week 8 (W8). Before (week 0, W0) and after (week 9, W9) the training period, horses performed an incremental continuous exercise test during which cardiorespiratory parameters were measured. Both groups progressed to the same extent regarding physical performance measured during interval training sessions (acceleration: 0.16m.s-2 at W0 and 0.40m.s-2 at W8; p < 0.0001), the 2400m performance test (average speed: 8.88m.s-1 at W0 and 10.55m.s-1 at W8; p < 0.0001), and the incremental continuous exercise test (speed during the fastest stage: 9.57m.s-1 at W0 and 10.53m.s-1 at W9; p = 0.030). Although oxygen consumption increased with training (p = 0.071), it was not influenced by the diet. On the contrary, carbon dioxide production increased in the high-starch group only (high-starch group: 84.0 vs. high-fibre group: 77.7mL.kg-1.min-1 at W9; p = 0.031). The results illustrate that horses in both groups progressed similarly but did not use the same metabolic pathways during exercise. This hypothesis is supported by carbohydrate oxidation, which tended to increase in the high-starch group at W9 but decreased in the high-fibre group (p = 0.061). In conclusion, the substitution of high-starch by high-fibre diets enabled similar performance over an 8-week training period and altered energy metabolism in a way that could be beneficial during high-intensity exercise.

Fibre Composition and Maturity of Forage-Based Diets Affects the Fluid Balance, Faecal Water-Holding Capacity and Microbial Ecosystem in French Trotters.

Racing events challenge the fluid balance of athletic horses. The equine large intestine functions as a fluid reservoir, since the properties of dietary forage fibre affect the digesta water content and the milieu of this ecosystem. This study aimed to investigate the effect of grass maturity and legume forage on the faecal water-holding capacity (WHC) and microbial ecosystem, and the fluid balance and body weight (BW) of French trotters in race training. Six geldings were offered three diets with different fibre compositions: concentrate and late-harvested mature grass haylage (35:65 energy ratio) (CMGH); early-harvested grass haylage and mature grass haylage (80:20) (EGH); and lucerne and mature grass haylage (80:20) (LH), for 24 days in a Latin square design. Body weights were lower and faecal WHC higher when the horses were fed EGH compared to CMGH and LH (485 vs. 492 and 492 kg, p < 0.001; 12.6 vs. 11.1 and 11.4 g H2O/g dry faeces, p = 0.014, respectively). Total water intake and output did not differ between diets, but water excretion via faeces was lower and via urine was greater on EGH compared to CMGH and LH (13.1 vs. 18.8 and 17.6 kg, p = 0.001; 10.5 vs. 7.6 and 7.9 kg, p = 0.032, respectively). Total bacteria concentrations were higher on EGH than CMGH and LH (5.4 × 1011 vs. 2.8 × 1011 and 2.8 × 1011 CFU/mL, p = 0.018, respectively). Concentrations of butyrate were greater, and pH was lower when fed EGH compared to CMGH and LH (3.0 vs. 2.0 and 1.6 mmol/L, p = 0.034; 6.5 vs. 6.9 and 7.2, p = 0.005, respectively). In conclusion, forage harvested at an early stage of maturity could benefit athletic horses' fluid balance by providing a more available large intestine fluid reservoir without increasing BW.

Genomic analysis of gaits and racing performance of the French trotter.

The aim was to disentangle gait characteristics from other qualities needed for racing performances with a genomic analysis of French trotters (FT). A sample of 1,390 horses were recruited, from which 46% were genotyped with Illumina chip of 54,602 SNPs, 49% with Affymetrix chip of 670,806 SNPs and 586 had a completed questionnaire on trotting technique. Racing performances cover the period 1996 to 2018. There were 252,368 FT‐born; 96,617 qualified and 83,962 which participated in a race. After quality control, 377,611 SNPs were retained and imputed. Questionnaire described trotting technique over 13 questions which were summarized, after principal component analysis in 3 traits: pacer, heavy trot/gallop and other defects. GWAS and genomic evaluation were performed using single‐step approach. We found 25 QTL for racing performances and 9 for trotting technique. Only DMRT3 mutation was significant for both traits. To tend to pace avoid the defect at gallop and lead to a better early career for earnings, less percentage of disqualified races at all ages and more harness than under saddle career. This is the portrait of AA genotype at DMRT3. We found 5 other QTL, not linked to gait traits, which might improve selection of genetically independent performance traits of earnings per races and percentage of finished races. For only earnings at different ages and in under saddle or harness races, genomic evaluation remains the best way to predict performances.

Impact of the individual characteristics of French trotters on their racing performance

The aim of this study was to investigate the influence of selected biometric characteristics on French trotters? racing performance. Moreover, the work attempts a prediction of racing performance indexes based on the horse?s individual characteristics, as well as the evaluation of the usefulness of an alternative method of a horse?s intravital measurements that limits the stress of the animal. A population of 64 horses of French trotter breed appearing in the Polish Stud Book of Trotters, which had participated in races in 2015, were subject to the investigation. The research material was represented by the indexes of racing performance combined with photobiometric measurements of those horses. It was proved that the angulation patterns of trotters' limbs have an influence on the value of racing performance indexes. The highest statistical significance was found for the pelvic limb. A significant discrepancy in the values of the racing performance indexes was found in the tested population. Furthermore, the usefulness of the alternative photo-biometric methods was proved. In conclusion, based on the results and using the presented method, a trotter horse can be visually examined in terms of its predisposition to win races.

English

The use of nutritional supplements for joint problems has received much attention in recent years. At this sight, Ovopet&reg;, an innovative ingredient from eggshell membrane that ensures the supply of nutrients necessary for the repair of joints together with anti-inflammatory compounds of natural origin, appears as a natural alternative supplementation for the treatment of joint problems in horses. Thus the aim of this study was to evaluate the effects of oral supplementation with Ovopet&reg; (eggshell membrane) in trotting horses with mild joint disease during the competing period to assess changes in some locomotor and physiological markers. Twenty French trotters positively identified as irregular or slightly lame were recruited and randomly assigned to either placebo or treatment group. The evaluations were done at days 0 and day 60 after the beginning of the treatment. The lameness, measured by the Equinosis&reg; Q with Lameness Locator&reg; was improved at low and medium speed in the horses intaking Ovopet&reg; while it was kept stable or worsened in the placebo group. The improvement in lameness could be related to a decline in pain in the treated group.&nbsp; Similarly, the minimum, mean and maximum heart rate were lower at day 60 compared to day 0 in Ovopet&reg; group. The heart rate variability whereas, was higher in Ovopet&reg; compared to placebo. Lower heart rate variability is associated with increased pain. At the sight of the present results, Ovopet&reg; appears as an alternative treatment to decline inflammation, pain and to improve the lameness of competing horses. Key words: Eggshell membrane, inflammation, lameness, ovopet&reg;, trotter. &nbsp

Global Epidemiological Analysis of Prevalence and Risk Factors Associated With the Deep Digital Flexor Tendinopathy in the Equine Distal Limb: 100 Cases

The purpose of this study was to establish the prevalence and the risk factors for deep digital flexor (DDF) distal tendinopathy in the equine limb (from the proximal extremity of the middle phalanx to the insertion of this tendon to the distal phalanx) and to identify the circumstances that promote this pathological condition. This epidemiological analysis was performed on 100 horses diagnosed with DDF distal tendinopathies at CIRALE-Hippolia between January 2009 and June 2010. All horses included in this study were diagnosed by ultrasonographic examination with front limb lameness associated with distal DDF tendinopathies at CIRALE-Hippolia in the aforementioned period. The sources of information were the individual medical records of horses. The considered risk factors were as follows: breed, age, sex, and athletic discipline. The risk was quantified by analyzing statistical association of the studied condition and different factors that can interfere with its evolution. Lameness associated with distal DDF tendinopathy has been mostly identified in jumping horses. The most well represented age category was the 8–10 years one, but the horses aged between 11 and 14 years had the highest risk for developing DDF tendinopathy. Females were more prone to this type of injury. The current epidemiological analysis provides a model for risk and protective factors for the development of DDF tendinopathy in the equine distal limb. The most susceptible group of equids are female Warmbloods more than the age of seven, whereas young male Thoroughbreds and French Trotters (0–3 year-old) carry the lowest risk in developing this pathology.

Effect of track surface firmness on the development of musculoskeletal injuries in French Trotters during four months of harness race training

OBJECTIVE To evaluate the effect of track surface firmness on the development of musculoskeletal injuries in French Trotters during 4 months of race training. ANIMALS 12 healthy 3-year-old French Trotters. PROCEDURES Horses were paired on the basis of sex and body mass. Horses within each pair were randomly assigned to either a hard-track or soft-track group. The counterclockwise training protocol was the same for both groups. Surface firmness of each track was monitored throughout the training period. Radiography, ultrasonography, MRI, and scintigraphy were performed on all 4 limbs of each horse before and after 2 and 4 months of training. Lesions were described, and lesion severity was classified with a 5-point system, where 0 = no lesions and 4 = severe lesion. RESULTS 86 lesions were identified, of which 46 (53.5%) were classified as potentially clinically relevant (grade, ≥ 2). Of the 18 moderate and severe lesions, 15 were identified in horses of the hard-track group, and 10 of those were in forelimbs. Moderate to severe tendinopathy of the superficial digital flexor tendon of the forelimb developed in 3 of the 6 horses of the hard-track group but none of the horses of the soft-track group. Metatarsal condyle injuries were more frequent in horses of the hard-track group than horses of the soft-track group. Severe lesions were identified only in left limbs. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that track surface firmness is a risk factor for musculoskeletal injuries in horses trained for harness racing.

Impact of training load on the heart rate of horses

Received: 2016-02-18 | Accepted: 2016-03-04 | Available online: 2016-12-22 http://dx.doi.org/10.15414/afz.2016.19.04.167-170 In our work, we analyzed the effect of training load on the heart rate of horses in a simulated load by the loading regulator for horse motion Horse Gym 2000. In the experiment were observed 8 Slovak Warmblood horses (3 mares, 4 geldings, 1 stallion) aged 6-10 years. The experiment was divided into two parts after three weeks. The speed of the tested horses was 4.9 km/h in the first part of experiment, in the second part was the speed 5.2 km/h with a gradual uphill up to 7 %. The tested horses achieved during the experiment an average heart rate level below 70 beats a minute, which is a light load. The maximum values of heart rate were recorded at 120 to 147 beats/min. Differences between tested horses in the values of heart rate were not statistically significant. After three weeks we recorded in the values of average and maximum heart rate onset of bradycardia, which is documented the adaptation of body to the specified load. Keywords: heart rate, horse, load, training References COUROUCE, A., CHRETIEN, M. and VALETTE, J. P. (2002) Physiological variables measured under field conditions according to age and state of training in French Trotters. Equine Veterinary Journal, vol. 34, pp. 91-97. CROSS, N. et al. (2008) Effects of lighting conditions on the welfare of horses being loaded for training. Journal of Veterinary Behavior, vol. 3, pp. 20-24. DOBSAK, P. (2009) Clinical physiology of physical load. Brno: Masaryk university, pp. 47-53. ENGELHARDT, W. V. (1977) Cardiovascular effect of exercise and training of horses. Adv. Vet. Sci. Comp. Med., vol. 21, pp. 173-205. EVANS, D. L. (2007) Physiology of equine performance and associated tests of function. Equine Veterinary Journal, vol. 33, p. 543. FREEMAN, J. V. et al. (2006) Autonomic nervous system interaction with the cardiovascular system during exercise. Progress in Cardiovascular Diseases, vol. 48, pp. 342-362. doi: http://dx.doi.org/10.1016/j.pcad.2005.11.003 HANAK, J. and OLEHLA, C. (2010) Clinical physiology of horses and their training. University of Veterinary and Pharmaceutical Science, Brno, pp. 130-136. KRZYWANEK, H. et al. (1970) The heart rates of Thoroughbred horses during a race. Equine Veterinary Journal, vol. 2, pp. 115-117. LEINO, J. et al. (2010) Exercise-test-related heart rate variability and mortality: The Finnish cardiovascular study. International Journal of Cardiology, vol. 144, pp. 154-155. doi: http://dx.doi.org/10.1016/j.ijcard.2008.12.123 LINDHOLM, A. and SALTIN, B. (1974) The physiological and biochemical response of standardbred horses to exercise of varying speed and duration. Acta Veterinaria Scandinavica, vol. 15, pp. 310-324. LITTLEJOHN, A. (1987) Exercise-related cardiovascular problems. In: ROBINSON, N. E. (ed.) Current therapy in equine medicine 2. Philadelphia: WB Saunders Co., p. 176. MARR, C. M. and BURTON, M. (2010) Cardiology of the horse. 2. ed. London: Elsevier. p. 84 MOHR, E., WITTE, E. and VOSS, B. (2000) Heart rate variability as stress indicator. Archive Tierzucht., Sonderheft, Dummerstorf, vol. 43, pp. 171-176. PERINI, R. and VEICTEINAS, A. (2003) Heart rate variability and autonomic activity at rest and during exercise in various physiological conditions. Eur. Journal Application Physiology, vol. 90, pp. 317-325. doi: http://dx.doi.org/10.1007/s00421-003-0953-9 PERSSON, S. G. B. (1967) On blood volume and working capacity in horses. Acta Veterinaria Scandinavica, vol. 19 (Suppl.), pp. 101-121. PERSSON, S. G. B. and LYDIN, G. (1973) Circulatory effects of splenectomy in the horse, III Effect on pulse-work relationship. Journal of Veterinary Medicine [A], vol. 20, pp. 521-530. POOPLE, D. C. and ERICKSON, H. H. (2004) Heart and vessels function during exercise and response to training. In: HINCHCLIFF, K. W., KANEPS, A. J., and GEOR, R. J. (eds.) Equine sports medicine and surgery. New York: Saunders, p. 699. SCHMIDT, A. et al. (2010) Cortisol release, heart rate, and heart rate variability in transport-naive horses during repeated road transport. Domestic Animal Endocrinology, vol. 3, pp. 205-213. VOSS, B., MOHR, E. and KRZYWANEK, H. (2002) Effects of aqua-treadmill exercise on selected blood parameters and on heart-rate variability of horses. Journal of Veterinary Medicine A, Physiology, Pathology and Clinical Medicine, vol. 49, no. 3, pp. 137-143. YOUNG, L. (2004) Diseases of the heart and vessels. In: HINCHCLIFF, K. W., KANEPS, A. J. and GEOR, R. J. (eds.) Equine sports medicine and surgery. New York: Saunders, p. 727.

Mesh repair of a large traumatic lateral abdominal wall hernia in an 8-day-old foal

Summary An 8-day-old French trotter colt was admitted with a traumatic lateral abdominal wall hernia with reducible intestinal content. A 15 cm long full thickness tear was identified in both the internal abdominal oblique and transverse abdominal muscles. This case report describes the surgical repair of the hernia using a polypropylene mesh.

Should we use the single nucleotide polymorphism linked to DMRT3 in genomic evaluation of French trotter?1

An A/C mutation responsible for the ability to pace in horses was recently discovered in the gene. It has also been proven that allele C has a negative effect on trotters' performances. However, in French trotters (FT), the frequency of allele A is only 77% due to an unexpected positive effect of allele C in late-career FT performances. Here we set out to ascertain whether the genotype at SNP (linked to ) should be used to compute EBV for FT. We used the genotypes of 630 horses, with 41,711 SNP retained. The pedigree comprised 5,699 horses. Qualification status (trotters need to complete a 2,000-m race within a limited time to begin their career) and earnings at different ages were precorrected for fixed effects and evaluated with a multitrait model. Estimated breeding values were computed with and without the genotype at SNP as a fixed effect in the model. The analyses were performed using pedigree only via BLUP and using the genotypes via genomic BLUP (GBLUP). The genotype at SNP was removed from the file of genotypes when already taken into account as a fixed effect. Alternatively, 3 groups of 100 candidates were used for validation. Validations were also performed on 50 random-clustered groups of 126 candidates and compared against the results of the 3 disjoint sets. For performances on which has a minor effect, the coefficients of correlation were not improved when the genotype at SNP was a fixed effect in the model (earnings at 3 and 4 yr). However, for traits proven strongly related to , the accuracy of evaluation was improved, increasing +0.17 for earnings at 2 yr, +0.04 for earnings at 5 yr and older, and +0.09 for qualification status (with the GBLUP method). For all traits, the bias was reduced when the SNP linked to was a fixed effect in the model. This work finds a clear rationale for using the genotype at for this multitrait evaluation. Genomic selection seemed to achieve better results than classic selection.

36 The DMRT3 “Gait keeper” mutation affects harness racing performance and riding traits in Finnhorses

s / Journal of Equine Veterinary Science 35 (2015) 398e399 399 36 The DMRT3 “Gait keeper” mutation affects harness racing performance and riding traits in Finnhorses K. J€aderkvist*, L. Johansson , A. Mykk€ anen , M. M€aenp€ a€ a , L.S. Andersson , L. Andersson , T. Arnason , and G. Lindgren 1 1 Swedish University of Agricultural Sciences, Uppsala, Sweden; University of Helsinki, Helsinki, Finland; 3 Suomen Hippos ry, Espoo, Finland; Uppsala University, Uppsala, Sweden; 5 IHBC AB, Knubbo, Morgongava, Sweden The DMRT3 “Gait keeper”mutation is well known for its effects on gaits and locomotion patterns in horses. Previous studies have shown the mutation to have a strong favorable effect on harness racing performance in Standardbreds, French and Nordic trotters. The mutation also affects riding traits in Icelandic horses and in Standardbreds. The aim of this study was to investigate the effect of the DMRT3mutation on harness racing performance and riding traits in Finnhorses. We genotyped for the DMRT3 mutation 180 Finnhorses of trotting type and 59 Finnhorses used for riding. For the trotters the genotypes were evaluated for association with racing performance traits (number of starts, victories, placings, earnings and race times) at different ages. For the Finnhorses used for riding the owners answered a 12 question survey about their horse and had to score how well the horse performed the gaits walk, trot and canter on a scale from 1 to 6. T€ olt and pace ability was also reported. These scores were then tested for an association with the DMRT3 genotypes. Racing performance analyses were performed usingWald tests in PLINK. Fisher's exact tests in R were used for analyses on t€ olt and pace ability, while pairwise t-tests were used for gait score analyses. The results showed that the DMRT3 mutation strongly influenced racing performance in Finnhorses. Between 3 and 6 years of age AA horses had a significantly higher proportion of victories (P1⁄4 1.4 10 6) and placings (P 1⁄4 4.1 10 7) compared with Chorses. Additionally, they also had better race times (P 1⁄4 0.01) and earned more money (P 1⁄4 0.009). Despite CA horses not performing as well as AA horses, they still performed better than CC horses. Thus supporting an additive genetic effect of the DMRT3 mutation on racing performance. Similar results were found when comparing performance at different ages (4, 5, 6 and 10 years), except for 3 years of age where no significant differences were present. Although AA horses were more successful as racehorses, the Chorses appear more adapted for classical riding disciplines. This is supported by significantly lower gait scores for AA horses compared with Chorses for the majority of gaits. With the exception of rhythm in extended canter (P 1⁄4 0.05), no significant differences were present between CA and CC horses for gait scores. A significant association (P 1⁄4 0.006) between DMRT3 genotype and the ability to show t€ olt was present; however, no significant association was present for pace (P 1⁄4 0.21). This study shows that different genotypes are optimal for different disciplines and the DMRT3 mutation clearly influences the pattern of locomotion in Finnhorses.

Does heterozygosity at the DMRT3 gene make French trotters better racers?

BackgroundRecently, a mutation was discovered in the DMRT3 gene that controls pacing in horses. The mutant allele A is fixed in the American Standardbred trotter breed, while in the French trotter breed, the frequency of the wild-type allele C is still 24%. This study aimed at measuring the effect of DMRT3 genotypes on the performance of French trotters and explaining why the polymorphism still occurs in this breed. Using a mixed animal model, genetic parameters and environmental effects on performance traits were estimated from data on 173 176 French trotter races. The effect of the DMRT3 gene was then estimated by the effect of genotype at the highly linked SNP BIEC2-620109 (C-C, A-T) for 630 horses. A selection scheme that included qualification and racing performances was modeled to (1) verify if the observed superiority of heterozygous CT horses at this SNP could be explained only by selection and (2) understand why allele C has not disappeared in French trotters.ResultsHeritability of racing performance traits was high for qualification test (0.56), moderate for annual earnings per finished race (0.26 to 0.31) and low for proportion of disqualified races (0.06 to 0.09). Genotype CC was always unfavorable compared to genotype TT for qualification: the probability to be qualified was 20% for CC vs. 48% for TT and earnings were -0.96 σy lower for CC than for TT. Genotype CT was also unfavorable for qualification (40%) and earnings at 3 years (-0.21 σy), but favorable for earnings at ages greater than 5 years: +0.41 σy (P = 7.10−4). Selection on qualification could not explain more than 19% of the difference between genotypes CC and CT in earnings at ages greater than 5 years. Only a scenario for which genotype CT has a favorable effect on the performance of horses older than 5 years could explain that the polymorphism at the DMRT3 gene still exists in the French trotter breed.ConclusionsThe use of mature horses in the French racing circuit can explain that the CA genotype is still present in the French trotter horses.

Technical note: Comparison of two methods to quantify exercise energy expenditure in trotters

This study aimed at quantifying energy expenditure during 4 specific training exercises, that is, promenade, jogging, parcours, and interval exercises, using field measurements of oxygen consumption and heart rate in trotters. Six animals performed 2 preliminary tests to determine their individual maximum velocity and to establish their individual oxygen consumption/heart rate relationship from an incremental test. Then, they undertook each of the 4 specific exercises separated by 1 wk to avoid fatigue. The intensity of the 4 exercises was expressed in percent of individual maximum velocity as well as duration and distance set according to current training practices of French trotter trainers. Throughout the incremental test and the 4 exercises, oxygen consumption and heart rate were continuously recorded using a portable respiratory gas analyzer. Energy expenditure of the 3 different phases (warm-up, exercise, and recovery) of the 4 exercises and the total energy expended during exercises (sum of energy expended during the 3 phases) were calculated from direct oxygen uptake measurements and from estimated oxygen uptake using heart rate and O caloric equivalent. The quantification of total energy expenditure from the 2 methods was not significantly different. However, estimated energy expenditure was significantly lower from estimated oxygen consumption than direct oxygen uptake method concerning the warm-up and exercise phase of parcours. Our results indicate that the estimated oxygen uptake from heart rate measurements could be used to evaluate total energy expenditure of exercises in trotters. Whereas this method requires previous establishment of an individual oxygen consumption/heart rate curve, it is easy to record using commercially available instruments under practical conditions and opens new perspectives to assess energy balance in trotters' nutrition.

Should we use the SNP linked to DMRT3 in genomic evaluation of French trotter?

Should we use the SNP linked to <em>DMRT3</em> in genomic evaluation of French trotter?

Longitudinal Follow‐Up of Bronchoalveolar Lavage Cytology in Standardbred Racehorses

IntroductionBronchoalveolar lavage (BAL) fluid cytology is a major diagnostic method for detecting exercise‐induced pulmonary haemorrhage (EIPH) and inflammatory airway disease (IAD) in racehorses. Our hypothesis was that training and racing would increase the incidence of IAD and EIPH.MethodsOn three different occasions (day‐1, −30 and −60), BAL fluid was obtained from both lungs of 14 Standardbred trotters with similar age and training level. Cytological inclusion criteria were neutrophils &gt;10%, and/or mast cells ≥5%, and/or eosinophils ≥5% for IAD, and haemosiderophage/macrophage (H/M) ratio &gt;20% for EIPH. Since previously found not to be equivalent, both samples from each horse were independently investigated. Horse status (‘IAD’,‘EIPH’, ‘mixed’, or ‘control’) at each time point was based on cytological profiles from both lungs. Cell proportions were compared by repeated measures ANOVA.ResultsHaemosiderophage proportions and H/M were significantly higher on day‐60 compared to day‐1. No significant difference was observed for other cell proportions. On day‐1, 5 horses were ‘control’, 2 ‘IAD’, 2 ‘EIPH, and 5 were ‘mixed’. On day‐30, 3 horses were ‘control’, 4 ‘IAD’, 2 ‘EIPH’, and 5 were ‘mixed’. On day‐60, 3 horses were ‘control’, 0 ‘IAD’, 3 ‘EIPH’, and 8 ‘mixed’. Despite the different horses′ distribution within each category, an overall increase in EIPH was observed. Five of the 7 horses classified ‘control’ or ‘IAD’ on day‐1 presented EIPH on day‐30 and/or −60. EIPH was detected in 11/14 horses (78.6%) on day‐60, versus 7/14 horses (50%) on day‐1.ConclusionsThe incidence of EIPH, but not IAD, significantly increased during a racing season. This evolution should be considered when assessing BAL fluid cytology in racehorses.Ethical Animal ResearchThe study was approved by the regional Animal Ethics Committee (n°CEEA.2012.179) and all owners signed a consent form. Sources of funding: IFCE (National Studs) and SECF (French Trotters Racing Association). Competing interests: none.

Quantification of Energy Expenditure in Field Conditions: Comparison of Direct VO2 Versus VO2 Estimation from Heart Rate Measurements

IntroductionIn humans, oxygen consumption (VO2) and heart rate (HR) are commonly used to assess energy expenditure (EE) during exercise in field conditions. We hypothesized that the estimation of EE from HR measurements could be a relevant parameter to estimate EE during submaximal field exercise. This study aimed to compare the EE from VO2 and HR measurements in exercising trotters.MethodsSix harnessed French Trotters were submitted to a continuous field incremental test (FIT) at trot to establish their individual VO2/HR relationship. Then they undertook a submaximal exercise bout (EX) over 2375 m during 3.41 ± 0.47 min at 70% of maximal velocity. VO2 and HR were recorded continuously (equine K4b2, COSMED, Rome, Italy) throughout FIT and EX. EE of EX was calculated by multiplying the total VO2 (Liters), either directly measured or predicted from HR, with its caloric equivalent (4.86 kcal/liter). Means were compared using a Student's t test.ResultsEE of EX was estimated at 2422 ± 390 kcal and 2630 ± 706 kcal from direct VO2 and HR methods respectively (P = 0.54).ConclusionsWe found no significant difference between the two methods for estimating EE of submaximal exercise. This suggests that the prediction of EE from HR monitoring might be used to evaluate EE of moderate intensity workouts.Ethical Animal ResearchThe project was conducted under the ethics committee approval B1110. Sources of funding: INRA PHASE, the Burgundy Region and AgroSup Dijon. Competing interests: none.

Involvement of mitochondrial dysfunction and ER-stress in the physiopathology of equine osteochondritis dissecans (OCD)

Osteochondrosis (OC) is a developmental bone disorder affecting several mammalian species including the horse. Equine OC is described as a focal disruption of endochondral ossification, leading to osteochondral lesions (osteochondritis dissecans, OCD) that may release free bodies within the joint. OCD lesions trigger joint swelling, stiffness and lameness and affects about 30% of the equine population. OCD is considered as multifactorial but its physiopathology is still poorly understood and genes involved in genetic predisposition are still unknown. Our study compared two healthy and two OC-affected 18-month-old French Trotters diagnosed with OCD lesions at the intermediate ridge of the distal tibia. A comparative shot-gun proteomic analysis of non-wounded cartilage and sub-chondral bone from healthy (healthy samples) and OC-affected foals (predisposed samples) identified 83 and 53 modulated proteins, respectively. These proteins are involved in various biological pathways including matrix structure and maintenance, protein biosynthesis, folding and transport, mitochondrial activity, energy and calcium metabolism. Transmission electron microscopy revealed typical features of mitochondrial swelling and ER-stress, such as large, empty mitochondria, and hyper-dilated rough endoplasmic reticulum, in the deep zone of both OC lesions and predisposed cartilage. Abnormal fibril organization surrounding chondrocytes and abnormal features at the ossification front were also observed. Combining these findings with quantitative trait loci and whole genome sequencing results identified about 140 functional candidate genes carrying putative damaging mutations in 30 QTL regions. In summary, our study suggests that OCD lesions may result from defective hypertrophic terminal differentiation associated with mitochondrial dysfunction and ER-stress, leading to impaired cartilage and bone biomechanical properties, making them prone to fractures. In addition, 11 modulated proteins and several candidate mutations located in QTL regions were identified, bringing new insight into the molecular physiopathology and genetic basis of OCD.

Bronchoalveolar lavage fluid in Standardbred racehorses: Influence of unilateral/bilateral profiles and cut-off values on lower airway disease diagnosis

The aim of this study was to determine whether the lung side being sampled would significantly influence bronchoalveolar lavage (BAL) cytological profiles and subsequent diagnosis in Standardbred racehorses. One hundred and thirty-eight French Trotters in active training and racing were included in a prospective observational study. BAL was performed using videoendoscopy in both right and left lungs during summer meetings in 2011 (64 horses) and 2012 (74 horses). Cytological data performed 24h later from right and left lungs were compared and specifically used to classify horses as affected with exercise-induced pulmonary haemorrhage (EIPH), inflammatory airway disease (IAD), or were ‘controls’. For IAD, cytological definition was based on two different cut off values.Neutrophil percentages, haemosiderophage percentages and the haemosiderophage/macrophage (H/M) ratios were significantly higher in the right compared to the left lung. Measures of intra-class correlation coefficients revealed a fair agreement between left and right lungs for percentages of mast cells, eosinophils, and for the H/M ratio, and a moderate agreement for neutrophil percentages. Fair to moderate agreements were observed between left and right lungs for the diagnosis of IAD and/or EIPH based on kappa coefficients. When sampling one lung only, the risk of incorrectly classifying a horse as a ‘control’ increased with the use of the restraint cut-off values for IAD. As BAL from one lung is not representative of the other lung in the same horse, both lungs should be sampled for a better assessment of lung cellularity and for a precise diagnosis of lower airway diseases.