Young Horses Research Articles

27 Incidence rate of lesions in the distal forelimb of growing, exercising sheep as a model for horses

The use of circular exercise is prominent in the equine industry, but this practice may result in joint damage which can be indicated by macroscopic characteristics such as cartilage lesions. Compromised integrity of the joint often results in pain that presents as lameness and decreased performance. Cartilage lesions can also be indicative of chronic disabling conditions such as osteoarthritis. To evaluate the effects of circular exercise on joint health, 42 sheep (4 mo old, 40 ± 1 kg) were used as a model for young horses. Animals were striated by sex and weight, then randomly assigned to the following treatments: straight line slow, straight line fast, small circle slow, small circle fast, large circle slow, large circle fast, and non-exercised control. Straight line exercise was conducted on a treadmill, and circular exercise was conducted via mechanical walker in a clockwise direction on a 12-m diameter circle (small) or an 18-m diameter circle (large). Exercise occurred 4 d/wk for 12 wks starting at 390 m/d (slow: 5.0 min/d at 1.3 m/s; fast: 4 min/d at 1.3 m/s and 0.7 min/d at 2.0 m/s). Exercise increased weekly until animals reached 2,340 m/d (slow: 30 min/d at 1.3 m/s; fast: 24 min/d at 1.3 m/s and 3.9 min/d at 2.0 m/s). Sheep were housed in group pens (34 m2, bedded with straw) and fed a standard balanced diet with free choice grass hay. At the end of the study,animals weighed an average of 54 ± 1 kg and were humanely euthanized via captive bolt. All carpal and metacarpophalangeal joint capsules were opened and analyzed for number of lesions and lesion surface area using ImageJ software (NIH). Data were analyzed by Proc Freq and Proc Mixed in SAS 9.4. Only one sheep (straight line fast group) displayed an acute lameness for 5 d. At the completion of the study, sheep had reached 70% of their mature BW, increasing their size by 35% during the 3 mo, averaging 0.17 kg/d. Within the 42 sheep, a total of 322 lesions were observed with 99% in the carpal joint and 1% in the metacarpophalangeal joint. Average lesion surface area in the carpal joint was 22 ± 1 mm2 versus 1.6 ± 0.3 mm2 in the metacarpophalangeal joint (P < 0.05). Within the carpal joint, 52% of lesions were found in the carpometacarpal joint, 36% in the middle carpal joint, and 12% in the radiocarpal joint. No differences were found among treatment groups or limbs. These data suggest exercise was not the sole contributor to lesion development, emphasizing that growth rate, diet, and genetic components must also be considered when evaluating the cause of cartilage lesions.

115 Effect of an enriched social environment on social maturation of horses

Conventional husbandry practices rarely allow for sociality of horses. Under natural conditions, horses learn the social codes of their group mates during the first years of life. Horses raised in box stalls have more aggressive interactions with humans than horses housed in a group setting in a pasture. Such conditions can potentially compromise the well-being of the horses. The study aimed at providing Information on the temporal evolution of the young horse's behavior in a social group to estimate better the exact age of social maturity. The study was run in a breeding stud for sport horses born and raised in large social all-age groups (20–60 horses), always outdoors on large pastures and fed roughage only. Salt lick was available. From the age of 4 years, the behavior of 9 horses was observed daily during daytime (6 h between 8:00 a.m. and 8:00 p.m.) between June and August each year for 3 consecutive years. Each horse was observed for a total of at least 90 h and its social interactions (defensive, offensive, or affiliative) were recorded. The data was analyzed with a GLMM. The type of interaction was considered a fixed factor in interaction with age and season. The identity of horses was considered a random factor. We found that 4yrs-old horses had fewer defensive interactions than 5- and 6yrs-old horses (4yrs-5yrs P < 0.0001, 4yrs-6yrs P < 0.001). The affiliative and offensive interactions decreased continuously fromthe age of 4 to 6 yrs with 5yrs old showing in between levels (Affiliative: 4yrs-5yrs P < 0.0001, 5yrs-6yrs P < 0.001, 4yrs-6yrs P < 0.001; Offensive: 5yrs-6yrs P = 0.009, 4yrs-5yrs P < 0.001, 4yrs-6yrs P < 0.001). While getting older, horses expressed less offensive agonistic behavior and more defensive behavior suggesting a phenomenon of social maturation from the age of 4 to 6 years. This might be the consequence of a better ability to establish and respect the group's dominance hierarchy. It is also possible that more mature horses stay closer to same-rank individuals, unlike younger ones, decreasing then the risk of offensive interactions. The fact that the decrease in affiliative interactions was associated with a decrease in offensive interactions go along with the hypothesis of a social maturation and the development of better socio-cognitive skills. This development of social behavior questions the fact that many horses are traditionally isolated from congeners when they start working, from the age of 2, latest 3 years old. Our results suggest that such horses are excluded from a social group during a sensitive period of social maturation. This could induce a lack of social skills that could be necessary later for interacting normal with congeners and humans.

Effects of different LED lighting conditions on young horses during trailer loading and stationary confinement

Effects of different LED lighting conditions on young horses during trailer loading and stationary confinement

Development of measures in the field of veterinary and sanitary requirements for the safety of herd horse breeding products

Infectious diseases such as salmonellosis, strangles and rhinopneumonia of horses remain an unsolved task of veterinary practice not only in the Republic of Sakha (Yakutia), but also in other regions of Russia where herd horse breeding is developed. Only in recent years, after scientists of the Yakut Research Institute of Agriculture have developed highly immunogenic vaccines such as "Salmonella abortion vaccine", "Inactivated horse strangles vaccine" and at the approval stage "Divalent vaccine against rhinopneumonia and equine salmonellosis", "Combined vaccine against rhinopneumonia and strangles horse for young horses", epizootological the situation in the republic. In the process of introducing these vaccines in disadvantaged farms, the quality of horse meat and foal supplied is assessed by conducting organoleptic, physico-chemical, microbiological, chemical-toxicological and radiological studies. All studies were conducted in compliance with standards and norms. Enzyme immunoassay proved the circulation of the rhinopneumonia virus in farms where vaccinations were not carried out. Salmonella abortion and horse strangles are registered annually in the republic. Infectious diseases create a barrier to the export of horse breeding products. We are developing a scheme of preventive veterinary and sanitary measures for horse breeding farms of the republic that are disadvantaged by infectious diseases of horses. One of its important points is to improve the quality of products obtained from horse breeding. During the implementation of these measures, mares and young horses were immunized with vaccines developed by us in the farms of Tattinsky, Megino-Kangalassky and Ust-Aldansky uluses. Vaccinated animals received the probiotic "Sakhabactisubtil" with food. The business output of foals from vaccinated mares increased by 10-30%. A veterinary and sanitary examination of the foal was carried out. Microbiological examination of 50 samples of meat in 2 samples revealed bacteria of the Escherichia coli group. According to other indicators, the studied meat samples correspond to TR CU 021/2011 "On food safety", TR CU 034/2013 "On the safety of meat and meat products". Export of foals from the republic is possible after recovery from rhinopneumonia and annual vaccination against salmonella abortion and horse strangles.

The use of vitamin and mineral complexes in young horses feeding

The article presents the results of research on the use of vitamin and mineral complexes «Ippomin Junior» and «Ippovit» in feeding young Russian trotting breed of horses in the conditions of LLC «Stud farm «Lokotskaya». The main feeding ration of young animals of the first experimental group additionally included 50 g/head of the feed additive «Ippomin Junior» and the second experimental group 175 g / head of the feed additive «Ippovit». The use of vitamin and mineral complex «Ippomin Junior» and «Ippovit» allowed to balance the level of macro- and microelements, as well as vitamin D in the feeding diets of young horses to the recommended feeding standards. In addition, a biochemical blood test also showed normalization of the main indicators that do not exceed the permissible limits, which indicates an improvement in metabolism when using vitamin and mineral complexes. The best growth and development indicators were established in the experimental groups. In the first experimental group, the height at the withers increased by 3.4%, in the second experimental group – by 3.5%, in the control group – by 1.3%; oblique trunk length by 6.3%, 4.1% and 1.8%, respectively; chest circumference – by 4.0%, 3.9% and 2.4%, respectively; pastern girth in young animals in the experimental groups by 2.4%, in the control group – by 1.4%. The live weight of young horses during the study period in the control group increased by 10.5%, in the first experimental group by 11.1%, in the second experimental group by 19.8%.

Voice

The role of voice in work relations with horses has been little studied. However, the results of the research we conducted into the professional training of young horses, shows that equestrians’ use of voice dominates training. Our results demonstrate a specific tessitura in the voices of the equestrians (from medium to medium-low), as well as a ternary rhythm in the voices of the most experienced among them. This results of our exploratory study confirm the interest of studying the role of voice in the construction of an interspecies tie between humans and horses, and the place of affectivity at work.

Metastatic undifferentiated sarcoma in a horse

SummaryA 6‐year‐old Thoroughbred gelding was evaluated for surgical treatment of a firm, nonpainful cervical mass. The mass developed over 9 months but began enlarging rapidly 4 months prior to presentation. Previous biopsies were inconclusive. Ultrasonography of the cranioventral neck identified a heterogenous, 20 cm × 9 cm × 10 cm mass separate from the thyroid gland and extending caudally from the level of the hyoid apparatus. The gelding was clinically healthy at presentation. Surgical resection of the mass was performed under general anaesthesia. Histopathology and immunohistochemistry staining revealed an undifferentiated sarcoma with incomplete margins. Diagnostic staging tests, re‐excision and adjuvant chemotherapy were recommended, but the horse died suddenly before further treatment could be pursued. Post‐mortem examination revealed a recurrent cranioventral cervical mass in addition to haemothorax and widespread intra‐thoracic and intra‐abdominal multiorgan metastasis. To the authors' knowledge, this report documents the first undifferentiated sarcoma with systemic metastatic disease resulting in the sudden death of a young horse.

Contribution of woody plants to horses’ diets in Mediterranean rangelands

In Mediterranean countries, shrubby and woody areas provide herds with cheap fodder. However, some horse farmers are reluctant to use woody rangelands, which they associate with low-quality feed. In this article, we explore some aspects of the feeding behavior of horses on Mediterranean shrubby and woody rangelands, in order to document their pastoral interest for horses. We observed the feeding choices of young horses grazing on typical peri-Mediterranean rangelands. Observations were repeated at two sites, with four horses per site, over four days with two observers. At each site, two horses were fitted with GPS (positioning system) collars to determine their presence in different areas of the paddocks. Ingested plants were classified in a coding grid. The chemical characteristics of each feed item were estimated by near-infrared spectroscopy (NIRS). A hierarchical classification of NIRS spectra defined four classes. Leaves, twigs, and flowers of several woody species were ingested (1‒18% of recorded bites), although herbaceous species were preferred (&gt; 80% of bites). Horses explored the entire paddocks but grazed preferentially in open areas. The differences observed between sites suggested a strong effect of local grazing conditions. The chemical composition of feed from shrubs and trees was close to that of herbaceous forbs but quite different from that of grasses. Three out of four classes associated woody plants and forbs. These classes had interesting nutritional characteristics (protein &gt; 12%). These results confirm the positive contribution of woody plants to horses' nutrition, in addition to the other roles of woody plants in the well-being of horses on pasture.

“Dropping” in male horses during training: Part 2. Video observations

Dropping (penile tumescence) in male horses has been related to the provision of food rewards but it is unclear why horses display this behaviour. The objective of this observational study was to characterize dropping in relation to other behavioural indicators. Trainers submitted videos of their training session with their horse (n = 24). Frequency of behaviours (oral, head position, tail swish), rewards (treats) and duration of penile characteristics (partial or full drop, flaccid or erect) were noted for multiple 2 min segments of the training session. Chi-squared analyses compared penile characteristics to rewards. A mixed model analyzed the effects of horse age and training segment on behaviours and penile characteristics. Dropping occurred 69 % of the time with either a flaccid or erect penis. In the first 2 min horses spent less time with a fully dropped and erect penis than later in the training session (p < .02). Horses 11–15 yrs were fully dropped (82 % of the time) and erect (65 % of the time) longer than older and younger horses (p < .0001). Horses spent less time fully dropped (15 %) when trainers did not use treats compared to when they did (42 %; p < .03). The number of dropping bouts did not differ regardless of whether treats were provided or not (p = .3672). Neither the use of touch (p = .6861) nor the use of the clicker (p = .3795) were related to dropping during training sessions. The horses exhibited shorter durations of being fully dropped (p = .0016) and fully erect (p = .0253) during afternoon training sessions compared to morning and evening training sessions. No stress-related behaviours (head positioning, tail swishing, lip licking) were related to dropping (p > .05) however lip licking did occur more frequently during the last two minutes of the session (p = .0003). From these observations it can be suggested that dropping is not a sign of stress but may relate to the affective state of the horse.

Factor analysis of evaluated and linearly scored traits in Swedish Warmblood horses.

Assessment protocols to describe the various aspects of conformation, gait and jumping traits on a linear scale were introduced at young horse tests for Swedish Warmblood horses in 2013. The traits scored on a linear scale are assumed to be less subjective and more easily compared across populations than the traditional evaluated traits that are scored relative to the breeding goal. However, the resulting number of traits is considerable, and several of the traits are correlated. The aim of this study was to investigate the interrelationship between the different evaluated and linearly scored traits in Swedish Warmbloods using factor analysis. In total, 20,935 horses born 1996-2017 had information on evaluated traits, and 5450 of these also had linearly scored trait records assessed since 2014 when the protocol was updated. A factor analysis with varimax rotation was performed separately for evaluated and linearly scored traits using the Psych package in R. Height at withers was included in both analyses. A total of four factors for evaluated traits and 14 factors for linearly scored traits were kept for further analysis. Missing values for individual traits in horses with linearly scored trait records were imputed based on correlated traits before factor scores were calculated using factor loadings. Genetic parameters for, and correlations between, the resulting underlying factors were estimated using multiple-trait animal models in the BLUPF90 package. Heritability estimates were on a similar level as for the traits currently used in the genetic evaluation, ranging from 0.05 for the factor for linearly scored traits named L.behaviour (dominated by traits related to behaviour) to 0.59 for the factor for evaluated traits named E.size (dominated by height at withers and conformation). For both types of traits, separate factors were formed for jumping and gait traits, as well as for body size. High genetic correlations were estimated between such corresponding factors for evaluated traits and factors for linearly scored traits. In conclusion, factor analysis could be used to reduce the number of traits to be included in multiple-trait genetic evaluation or in genomic analysis for warmblood horses. It can also contribute to a better understanding of the interrelationships among the assessed traits and be useful to decide on subgroups of traits to be used in several multiple-trait evaluations on groups of original traits.

Longitudinal Training and Workload Assessment in Young Friesian Stallions in Relation to Fitness, Part 2-An Adapted Training Program.

Young Friesian stallions have to complete a 10-week training program (70-day test) for acceptance as a breeding stallion. Part one of this study showed that the 70-day test was too intense and led to reduced fitness. In the present (part two) study, the effects of an adapted training program were studied. Training frequency and minutes of cantering per week were lowered compared with part one. The external workload (EW) of sixteen stallions (3.4 ± 0.8 years) was monitored during the 6-weeks before testing (preparation period) as well as during the 70-day test. Standardized exercise tests (SETs) were performed in week 1 (SET-I), 6 (SET-II), and 10 (SET-III) of the 70-day test, measuring heart rate (HR) and plasma lactate concentration (LA). Linear mixed effect models were used to analyze the EW, and the HR and LA related to the SETs. The EW increased from the preparation period to the 70-day test; this increase in the EW was lower compared with the original training program. The horses showed lower HR and LA levels in SET-III compared with SET-I. The young Friesian horses were at risk to be overtrained in part one, but the adapted training program resulted in increased fitness. This study shows that a carefully chosen program is necessary to improve the performance and welfare of (young) horses.

The Reporting of Racehorse Fatalities in New Zealand Thoroughbred Flat Racing in the 2011/12-2021/22 Seasons.

Race day fatalities as a consequence of catastrophic musculoskeletal injury and cardiac failure are both a welfare concern and provide a challenge for the social perceptions of equine welfare within the racing industry. To reduce race day fatalities, the risk factors under New Zealand racing conditions need to be identified. The aim of this study was to examine race and horse-level risk factors for fatalities in New Zealand Thoroughbred flat racing using retrospective race day data from the 2011/12-2021/22 racing seasons. Horse and race-level factors associated with a suspected cardiac failure and fatal fracture were identified by merging fatality data with the master race dataset for the corresponding seasons. Most fatalities were associated with fatal fracture (0.4 per 1000 starts, 95% CI 0.4-0.5). Horses which raced over distances > 1600 m were 1.7 times (95% CI 1.2-2.5) more likely to sustain a fatal fracture than horses racing ≤ 1600 m. Male horses and firmer track conditions were also associated with an increase in the risk of fatal fracture. Horses aged 5 years and older were 2.1 (95% CI 1.1-4.6) times more likely to suffer a suspected cardiac failure than younger horses. Changes in the industry reporting system improved the level of detail provided for fatalities, enabling the identification of specific risk factors.

Sales and race performance of juvenile Thoroughbreds with surgically corrected large colon displacements.

Juvenile Thoroughbreds can be expensive to raise and train to race. Part of the economic return in these juveniles are the weanling, yearling and 2-year-old in training sales at which major surgeries must be declared. To determine if surgically corrected large colon displacements were associated with a reduction of sales price and racing performance. We hypothesised that the surgery would be associated with a reduced sales price but would not be associated with a reduction in race earnings or starts. Retrospective cohort study. The medical, sales and racing records of horses less than 2 years old that had a surgical diagnosis of large colon displacement were examined (n=110). Surgical cases were compared with a control group (n=299) whose sales and racing data were evaluated. There was no significant difference in median sale price overall between the two groups. Horses undergoing surgery had a reduced number of starts in the 2-year-old year (1 start; p < 0.001) when compared with control horses (2.32 starts), but no significant difference over the 2- to 4-year-old period. There was no significant association with surgery on earnings within the 2- to 4-year-old period of racing when compared with controls. The main limitations for this study were the retrospective design, relatively small number of horses and covering only the 2- to 4-year-old period of the horses' racing career. Overall, the results of this study suggest that if the juvenile Thoroughbred requires surgery for a large colon displacement, there is minimal association with sales price or race performance compared with their siblings. With this information, it will be easier to make informed decisions to take young horses to surgery.

Parasitic diseases prevention in herd horses in Yakutia

The purpose of the research is to study the spread of parasitic diseases that cause pathologies in horses and to evaluate the effectiveness of deworming with a feed and drug mixture that contains an effective anthelmintic and mineral supplement.Materials and methods. Seasonal and age helminth infection dynamics in young horses was studied by coproovoscopic and larvoscopic examinations monthly. A total of 50 foals were studied, namely, 20 foals aged under one year, 15 foals aged up to two years, and 15 foals aged up to three years. Infection prevalence and intensity in the horses was determined by the complete helminthological dissection of the gastrointestinal tract per K. I. Skrjabin. The detected helminths were fixed in 70% alcohol.Results and discussion. The most common Strongylata species were Alfortia edentatus, Delafondia vulgaris, Strongylus equinus and numerous species of Trichonematidae. The studied foals were showed the maximum prevalence of the S. equinus infection of 80% in November, and the minimum, 35.7% in August; the A. edentatus infection was 78.6 % in January, and 46.6% in November, respectively. The D. vulgaris infection peak of up to 86.6% was recorded in November-December, and the minimum, up to 66.6% in March. The foals were infected with Trichonematidae throughout the year.

Parâmetros genéticos para desempenho de salto em Cavalos Brasileiro de Hipismo

Abstract This study aimed to estimate genetic parameters for jumping measures in the Brazilian Sport Horses breed, looking to see which jump characteristics can be evaluated early and that present favorable genetic correlations (ϒg) with measures of later sports performance. Data were available for the results of jumping competitions on the Brazilian Sport Horses. Two traits were calculated: Classification (CLASS) of the animal (taking into consideration obstacle height, number of competitors, type of competition (regional, national, international) and final score (SCOREF) taking into consideration the weight of the competition, height of the obstacles and score for the placement and type of event. Heritabilities were low for the full database (0.00 and 0.07 for CLASS and SCOREF, respectively), but higher when only young horses were considered (0.09 and 0.67, respectively). Genetic correlations between these traits and subjective functional traits (using a scale of 0 to 10) measured at stallion approval for reproduction showed that Power was favorable for indirect selection for both traits (-0.85 for CLASS and 1.00 for SCOREF). Jump also showed a favorable correlation for SCOREF (0.53) but unfavorable for CLASS (1.00). Considering the importance of Temperament and the absence of unfavorable genetic correlations between it and competition results it was concluded that this trait can be maintained among the selection objectives of Brazilian Sport Horses. Suggestions are made for further genetic studies with this breed, and possible modifications in the evaluation regulations to improve data quality.

Hematological reference values of horses in Western Libya and their relationship to breed, age, and management.

Hematological evaluation is an important step for health assessment in equine medicine. Besides biochemical tests, that evaluation could be pivotal for diagnosis, prognosis, and treatment monitoring. In Libya, the horse population has drastically increased in the last years, and hitherto, no report addressed the reference hematological values for the existing equine breeds. This study aimed to establish the reference for hematological indices of traditional equestrian and stud-farm equine breeds in Western Libya in regard to some variables such as individual characteristics, management system, and rearing purpose. Blood samples of 167 horses of Arabian, Thoroughbred, and local breeds were collected from an area covering a large part of Western Libya and complete blood counts of the samples were performed using a hematological auto-analyzer. The collected data were statistically analyzed using the Statistical Package for Social Science software. Hematological reference indices were generated for the aforementioned equine breeds in Western Libya. The equine hematological profile was variable according to some individual and management factors. In addition, the significant effects of those factors were usually restricted to erythrocyte- and platelets (PLTs)-related indices. In terms of breed influence, Thoroughbreds had significantly lower erythrocyte counts of red blood cells (RBCs) compared to local horses (p = 0.04), and Arabian horses showed significantly higher PLT counts compared to Thoroughbreds and local horses; p = 0.00 and p = 0.03, respectively. Moreover, significantly lower values of hemoglobin (HGB), hematocrit (HCT), mean cell volume (MCV), and PLT counts were noticed in young horses vis-à-vis significantly higher values of HCT, mean corpuscular hemoglobin concentration and red cell distribution width in females. In regard to exercise, racing horses varied significantly from nonracing horses in monocyte percentage (p = 0.04), RBC (p = 0.00), HGB (p = 0.00), HCT (p = 0.00), MCV (p = 0.00), and mean corpuscular hemoglobin (MCH) (p = 0.00). Diet supplementation also influenced the equine erythrocyte-related indices, as horses offered supplemented diet had significantly higher RBC (p = 0.00), HGB (p = 0.00), HCT (p = 0.00), MCV (p = 0.00), and MCH (p = 0.00), comparing to those served nonsupplemented diet. This study provided the first reference values of the equine hematological profile in Western Libya. In addition, the age, breed, exercise, and diet supplementation had variable impacts on hematological equine indices.

Effect of a blend of magnesium oxide on Equine Squamous Gastric Disease in young trotter horses under training.

Equine squamous gastric disease (ESGD), as part of the equine gastric ulcer syndrome (EGUS), are common in racing horses. The use of buffering feed supplements to treat and/or prevent gastric ulcers is an option to control this condition. The purpose of this study was to evaluate the effect of a 30-day supplementation with a blend of magnesium oxide (MgO) on ESGD scores in trotters under training. Forty-two young trotters were submitted to a gastroscopic evaluation to assess their ESGD score and were randomly assigned in a group supplemented with MgO or in a control group. After 30 days, a second evaluation by gastroscopy was performed. The effect of the MgO supplementation was assessed by comparing the evolution of the ESGD score in supplemented and control groups between day 0 and day 30. The results confirm the high prevalence of EGUS in young Trotters. The supplementation significantly decreased the ESGD scoring in the supplemented group whereas the control group remain unchanged. The oral MgO supplementation was efficient to control ESGD in the population studied.

Successful cosmetic outcome of eyelid lacerations in a young male Marwari horse

Successful cosmetic outcome of eyelid lacerations in a young male Marwari horse

Some features of metabolism in horses of the Yakut breed

The results of studies on the biochemical parameters of the blood of 1.5-year- old young horses of the Yakut breed in comparison of well-fed and low-fed horses are pre- sented. The results revealed some significant discrepancies in the indicators of protein and carbohydrate-lipid metabolism. Normal digestion in a horse proceeds with a protein ratio of at least 1:9-11. With the loss of fatness, this ratio is violated, which leads to digestive dis- orders, and this in turn can lead to serious violations of the entire homeostasis in the body. And, apparently, this is why such animals get rid of the fetus in order to preserve their lives – an abortion occurs. Abortions of this nature are more likely to occur in winter with longer low temperatures: minus 45 ° C and below, with snow falling more than 50 cm deep. At the same time, in horses, first of all, the energy costs of maintaining thermoregulation and the costs of movement for obtaining tebenevochny feed increase. The most effective way to prevent alimentary abortions is stationary preventive feeding of horses until the fatness of horses decreases in early December and longer stationary feeding of horses for 30-45 days, depending on the fatness of horses, in February-March. Norms and feeding rations of foaled mares during stationary feeding should provide metabolic energy, protein, macro-microele- ments and vitamins in those quantities and proportions that would ensure rapid recovery of deficiency and a certain amount of substances in the body that allows comfortable foaling. Keywords: Yakut horse breed, metabolism, blood, biochemistry, young animals.

Influência do gênero e da idade no estágio de desenvolvimento ósseo e longevidade atlética de equinos da raça puro sangue inglês de corridas no Brasil - estudo preliminar

Abstract The impact of high-speed exercise on the musculoskeletal system of young racehorses has been extensively discussed because of concerns regarding animal health and welfare. This study investigated the correlation between age, degree of ossification of the distal radial epiphysis, sex, and career longevity of Thoroughbred racehorses in Brazil from 2012 to 2015. We performed a retrospective evaluation of 286 dorsopalmar radiographs of the left radiocarpal region of young horses and their racing performance. Distal radial epiphyseal closure was classified into three degrees: A, B, or C. Performance data included the number of races raced, athletic career length, and the number of races per month. The variables were subjected to regression analysis. At the time of radiographic examination, male horses were significantly older than females, and horses with epiphyseal closure degrees differed with age. Age at first race was 33.08±3.81 months, the average of races raced was 18.32±15.14 races, athletic career duration was 20.37±13.82 months, and the number of races raced per month was 0.93±0.46 races. Age influenced (P&gt;0.001) the distal radial epiphyseal closure on racehorses, but sex did not (P=0.218 for males and P=0.275 for females). An inverse association was observed between age at the first race, the number of races raced per month, and athletic career duration. The frequency of race and the age at the first race influenced athletic career duration.