Skeletal Muscle Adaptations to Exercise Training in Young and Aged Horses

In aged humans, low-intensity exercise increases mitochondrial density, function and oxidative capacity, decreases the prevalence of hybrid fibers, and increases lean muscle mass, but these adaptations have not been studied in aged horses. Effects of age and exercise training on muscle fiber type and size, satellite cell abundance, and mitochondrial volume density (citrate synthase activity; CS), function (cytochrome c oxidase activity; CCO), and integrative (per mg tissue) and intrinsic (per unit CS) oxidative capacities were evaluated in skeletal muscle from aged (n = 9; 22 ± 5 yr) and yearling (n = 8; 9.7 ± 0.7 mo) horses. Muscle was collected from the gluteus medius (GM) and triceps brachii at wk 0, 8, and 12 of exercise training. Data were analyzed using linear models with age, training, muscle, and all interactions as fixed effects. At wk 0, aged horses exhibited a lower percentage of type IIx (p = 0.0006) and greater percentage of hybrid IIa/x fibers (p = 0.002) in the GM, less satellite cells per type II fiber (p = 0.03), lesser integrative and intrinsic (p≤ 0.04) CCO activities, lesser integrative oxidative phosphorylation capacity with complex I (PCI; p = 0.02) and maximal electron transfer system capacity (ECI+II; p = 0.06), and greater intrinsic PCI, ECI+II, and electron transfer system capacity with complex II (ECII; p≤ 0.05) than young horses. The percentage of type IIx fibers increased (p < 0.0001) and of type IIa/x fibers decreased (p = 0.001) in the GM, and the number of satellite cells per type II fiber increased (p = 0.0006) in aged horses following exercise training. Conversely, the percentage of type IIa/x fibers increased (p ≤ 0.01) and of type IIx fibers decreased (p ≤ 0.002) in young horses. Integrative maximal oxidative capacity (p ≤ 0.02), ECI+II (p ≤ 0.07), and ECII (p = 0.0003) increased for both age groups from wk 0 to 12. Following exercise training, aged horses had a greater percentage of IIx (p ≤ 0.002) and lesser percentage of IIa/x fibers (p ≤ 0.07), and more satellite cells per type II fiber (p = 0.08) than young horses, but sustained lesser integrative and intrinsic CCO activities (p≤ 0.04) and greater intrinsic PCI, ECI+II, and ECII (p≤ 0.05). Exercise improved mitochondrial measures in young and aged horses; however, aged horses showed impaired mitochondrial function and differences in adaptation to exercise training.

Factors Associated with Fatality in Ontario Thoroughbred Racehorses: 2003–2015

Ontario’s Alcohol and Gaming Commission records equine racing fatalities through its Equine Health Program. The present study examined all Thoroughbred fatalities from 2003 to 2015, inclusive, to identify associations. Official records and details of fatalities were combined in multivariable logistic regression modelling of 236,386 race work-events (433 fatalities), and 459,013 workout work-events (252 fatalities). Fatality rates were 2.94/1000 race starts (all fatalities) and 1.96/1000 (breakdowns only) with an overall rate of 2.61% or 26.1 fatalities/1000 horses. Comparison with published reports reveals rates to be high. Musculoskeletal injury was the predominant complaint and there was a high incidence of horses dying suddenly. Liability was high for young horses early in the season with a differential according to sex and whether a male horse was gelded. Horses undertaking repeated workouts had a higher liability and liability was higher in workouts for horses switching from dirt/synthetic to turf racing and for young horses in sprints. Race distance was not significant but high fatality rates in some large field, distance races combined with effects of age and workload identified groups at particular risk. As field size increased, fatality liability increased for early-finishing horses. Findings suggest jockey strategy could be an important factor influencing fatalities. Probability of fatality declined over the study period. Findings indicate that rapid accumulation of workload in animals early in their preparation is likely to be damaging. Fatality fell toward the end of a season and for horses with a long career history of successful performance; however, horses not exhibiting this robustness and staying power represent the population of greatest concern. Associations may be characterised as representing sources of stress, current or cumulative, and identifying at-risk animals on this basis may be as productive as targeting specific, discrete mechanisms suspected to contribute to individual fatalities.

Responses to an intra-articular lipopolysaccharide challenge following dietary supplementation of Saccharomyces cerevisiae fermentation product in young horses

Dietary intervention may be a valuable strategy to optimize the intra-articular environment in young horses to prolong their performance career. To test the hypothesis that dietary supplementation of a Saccharomyces cerevisiae fermentation product would reduce markers of joint inflammation and increase markers of cartilage metabolism following a single inflammatory insult, Quarter Horse yearlings (mean ± SD; 9 ± 1.0 mo) were balanced by age, sex, body weight (BW), and farm of origin and randomly assigned to: 1.25% BW/d (dry matter basis) custom-formulated concentrate only (CON; n = 9) or concentrate top dressed with 21 g/d Saccharomyces cerevisiae fermentation product (SCFP; n = 10) for 98 d. Horses had ad libitum access to Coastal bermudagrass hay. On d 84, one randomly selected radial carpal joint from each horse was injected with 0.5 ng lipopolysaccharide solution (LPS). The remaining carpal joint was injected with sterile lactated Ringer’s solution as a contralateral control. Synovial fluid obtained before supplementation (d 0) and on d 84 at pre-injection h 0, and 6, 12, 24, 168, and 336 h post-injection was analyzed for prostaglandin E2 (PGE2), carboxypeptide of type II collagen (CPII), and collagenase cleavage neopeptide (C2C) by commercial assays. Rectal temperature, heart rate, respiration rate, carpal surface temperature, and carpal circumference (CC) were recorded prior to each sample collection and for 24 h post-injection. Data were analyzed using linear models with repeated measures. From d 0 to 84, synovial C2C declined (P ≤ 0.01) and the CPII:C2C ratio increased (P ≤ 0.01) in all horses with no effect of diet. In response to intra-articular LPS, synovial PGE2 increased by h 6 (P ≤ 0.01) and returned to baseline by h 336, CPII increased by h 12, remained elevated through h 168 (P ≤ 0.01), and returned to baseline by h 336, and C2C increased by h 6 (P ≤ 0.01) but did not return to baseline through h 336 (P ≤ 0.01). Post-intra-articular injection, PGE2 levels were lower in SCFP than CON horses (P = 0.01) regardless of injection type. Synovial CPII and the CPII:C2C ratio demonstrated stability during the LPS challenge in SCFP compared to CON horses (P ≤ 0.01). Clinical parameters were not influenced by diet but increased in response to repeated arthrocentesis (P ≤ 0.01). Dietary SCFP may favorably modulate intra-articular inflammation following an acute stressor and influence cartilage turnover in young horses.

Testing olfaction in equids: Age and gestational stage affects olfactory interest

In spite of the highly developed olfactory apparatus of horses, implying a high adaptive value, research on equine olfaction is sparse. Our limited knowledge poses a risk that horse behaviour does not match human expectations. The benefit of acquiring more knowledge of equine olfaction is therefore twofold; 1) it can aid the understanding of horse behaviour and hence reduce the risk of dangerous situations, and 2) there may be unexploited potential of using odours in several practical situations where humans interact with horses. This study investigated olfactory abilities of, 35 Icelandic, horses who were presented to four odours: peppermint, orange, lavender and cedarwood. The response variables were sniffing duration per presentation and behavioural reaction (licking, biting, snorting, and backing). Results showed horses were able to detect and distinguish between all four odours and showed increased interest (significantly longer sniffing duration) for peppermint. More horses expressed licking behaviour when presented to peppermint compared to cedarwood and lavender. Young horses sniffed cedarwood for longer than old horses, and pregnant mares sniffed lavender less than non-pregnant mares. In conclusion, the test paradigm seemed meaningful for horses, and olfactory interest of horses varied with age and gestational status but not sex.

Influence of Horse Age, Marinating Substances, and Frozen Storage on Horse Meat Quality

The present study analyzed the influence of horse age, substances used for marinating, and frozen storage on the quality of horse meat. It was conducted on the samples of the longest thoracic muscle, obtained from 12 carcasses of horses (aged 4–7 and 8–12 years). Among the analyzed samples, a higher fat content (p < 0.05) was found in the meat obtained from the carcasses of older horses. The pH value of the meat samples was influenced by the treatment applied (p < 0.05). Of the substances used for marinating, malic acid caused a decrease in the pH of the meat obtained from young horses (p < 0.05). A similar effect was observed with the addition of phosphates to malic acid-marinated meat. On the other hand, the use of phosphates for marinating resulted in an increase in the pH of the meat obtained from older horses (p < 0.05). The substances used for marinating the horse meat did not significantly affect the reduction in cutting force values. Furthermore, the values of shear force, hardness, stiffness, gumminess, and chewiness of the meat increased with horse age (p < 0.05). An influence on the color parameters a* and b* of the meat was found for the interaction between age, storage period, and the type of treatment (p < 0.05). The use of lactic acid and malic acid for marinating the meat of young horses caused a decrease in the proportion of red color (4.67 and 3.43) and an increase in the proportion of yellow color (3.81 and 1.71), especially after 3 months of freezer storage. All the substances used for marinating (except for phosphates) were associated with higher (p < 0.05) thermal and forced drips of meat from the carcasses of both young and older horses during each storage period, in comparison to the control. The interaction between age and the type of treatment had an influence on the tenderness and juiciness of the horse meat (p < 0.05). In sensory evaluation, it was noted that the interaction between age and the treatment procedure influenced the tenderness and juiciness of the meat samples (p < 0.05). There is still a need for further research to increase knowledge regarding how to improve the quality of horse meat, and ultimately increase the demand from consumers and meat processing plants.

Constitutional types of horses and resources for their homeopathic correction

Selective breeding is in vogue since centuries to improve horse’ breed. It aims at production of horses with special performance and bodily characteristics. It is a complex, costly and time-consuming occupation. But the characteristics of horses depends upon market demands. Many a times a horse, which possesses planned kineto, behavior, exterior characteristics, is not in demand anymore. For many years we performed horse “homeopathic correction” studies at ‘Griffon’ Stud Farm and Horse Club on the basis of A.A. Komissarenko’s theoretical developments. We have established that not only physical characteristics of studs are inherited, but also their psychic traits, which fit into a certain constitutional type of the stud. Among such different types it is possible to identify both harmonious and disharmonious type of animals. It has been established the homeopathic remedy regimen depends on the age of an animal. In our experience, efficient homeopathic correction should be performed once in three months during the entire life-time of a horse, to maintain their bodily and psychic characters. It is advisable to differentiate the constitutional characteristics of growing horses before fence training, as it may make it easier for the horse to grow and mature. In this case young horses attain good standard, have good height and psychic and physical characteristics. At the farm we performed homeopathic correction of pregnant animals once in the eight month of pregnancy that is at three months before colt delivery. Four colts were born, which were rated as top grade on the zootechnic scale of All-Russia’s Horse-breeding Research Institute (VNIIKВ). The evaluation is based on the animal activity at different times, during the first three years of the life. In our observation, colts born after homeopathic correction in the pregnancy period present better exterior and behavioural characteristics than others in their ancestor line. The outcome of our research is the conclusion that in horse breeding it makes sense to have early homeopathic correction. It improves animal’s performance, the rapport between horses and men and ensures horse’s career success. Achievements in production of impeccable growing horses were highly appreciated by Trakehner Union in Russia, and the Griffon Stud Farm became a full-fledged member of the Union in 2015. Utilization of homeopathy resources allows advance of zootechnic industry, as well as prompt response to market demand; the earlier such work begins, the more efficient and cost-effective it becomes.

Prevalence of Nasal Shedding of Equid Gammaherpesviruses in Healthy Swiss Horses

Equid Gamma herpesvirus (eGHV) infections have been reported worldwide and may be correlated with clinical signs, e.g., affecting the respiratory tract in young horses. eGHV are shed by healthy horses as well as horses with respiratory tract disease. The prevalence in healthy Swiss horses is unknown to date but this data would provide valuable information for causal diagnosis in clinical cases and formulation of biosecurity recommendations. Nasal swabs from 68 healthy horses from 12 Swiss stables and 2 stables near the Swiss border region in Germany were analyzed by panherpes nested PCR. Positive samples were sequenced. A multivariable model was used to determine if sex, age, breed, canton, or stable had a significant effect on the shedding status of each detected eGHV. Overall, the eGHV prevalence was 59% (n = 68); the prevalence for equid herpesvirus-2 (EHV-2), equid herpesvirus-5 (EHV-5) and asinine herpesvirus-5 (AHV-5) was 38%, 12% and 9%, respectively. Co-infections with multiple eGHVs were observed in 25% of the positive samples. The odds of shedding EHV-2 decreased with age (p = 0.01) whereas the odds of shedding AHV-5 increased with age (p = 0.04). Breed, sex, canton, or stable had no significant association with eGHV shedding. As EHV-2 shedding was common in healthy horses a positive PCR result must be interpreted with caution regarding the formulation of biosecurity recommendations and causal diagnosis. As EHV-5 and AHV-5 shedding was less common than EHV-2, a positive test result is more likely to be of clinical relevance. Shedding of multiple eGHV complicates the interpretation of positive test results in a horse.

Use and improvement of pastures for horse grazing in the Republic of Sakha (Yakutia): a review

Исследованы этапы становления лугопастбищного хозяйства Якутии применительно к табунному коневодству со средних веков до нашего времени. В таёжно-мелкодолинной зоне табунного коневодства Якутии необходимая площадь пастбищ для одной взрослой лошади в бесснежный период (165 дней) составляет 5,2 га при урожайности угодий в среднем по 2 т/га в натуральной массе, в зимний период (200 дней) — 11 га при урожайности угодий 0,53 т/га, или в год — 16–17 га. Создание сеяных травостоев из травосмесей регнерии ленской, костреца безостого, ломколосника ситникового, превосходящих по продуктивности естественные природные травостои в 2–2,5 раза, позволяет повысить конеёмкость кормовых угодий в 2 раза. В таёжно-аласной зоне табунного коневодства Центральной Якутии для создания высокопродуктивных сеяных сенокосно-тебенёвочных угодий на аласных лугах рекомендуются кострец безостый сорта Аммачаан и люцерна сорта Якутская жёлтая, а также кострец в чистом виде. Конеёмкость аласных угодий повышается в 1,5–2 раза. Для использования в качестве замороженных тебенёвочных кормов для молодняка в возрасте до 3 лет и маточного поголовья лошадей якутской породы из однолетних культур высокоэффективны овёс, а также овёс с ячменём в два летних срока посева: 25–30 июня — первый срок, 10–15 июля — второй срок. Пробы зелёной массы овса летнего срока посева в замороженном виде (октябрь-март) по кормовым достоинствам мало отличаются от проб зелёной массы овса, взятых на тех же посевах в тёплое время года. Рекомендуемые сроки тебенёвки молодняка — с середины ноября по апрель; сроки тебенёвки маточного поголовья — с февраля по апрель. При этом для рационального тебенёвочного использования угодий необходимо выделять отдельные участки от 5 до 20–25 га каждый. This review provides insights on pasture cultivation in Yakutia from the Middle Ages to these days. In the taiga-bottomland zone of horse herd farming an adult horse requires 5.2 ha of grazing area under grass productivity of 2 t ha-1, while in winter (200 days) — 11 ha under the productivity of 0.53 t ha-1 (16–17 annually). Planting swards of Regneria spp., smooth brome and Russian wildrye increases forage land productivity by 2 times since these crops exceed natural stands in productivity by 2–2.5 times. To obtain high-productive forage lands in the taiga-alas zone of the Central Yakutia smooth brome “Ammachaan” and alfalfa “Yakutskaya zheltaya” are recommended. Alas productivity increases by 1.5–2 times. Oats or oat mixtures with barley (planted on the 25–30th of June or 10–15th of July) are effective in feeding of young horses (up to 3 years old) or breeding stock as frozen feed. Frozen green mass of oats seeded in summer has similar forage characteristics as the one collected in warm period. The best period for young horse grazing is from the middle of November to April; breeding stock — from February to April. It is necessary to separate areas of 5–25 ha for efficient grazing.

Dietary supplementation of a Saccharomyces cerevisiae fermentation product attenuates exercise-induced stress markers in young horses

Mitigation of exercise-induced stress is of key interest in determining ways to optimize performance horse health. To test the hypothesis that dietary supplementation of a Saccharomyces cerevisiae fermentation product would decrease markers of exercise-induced stress and inflammation in young horses, Quarter Horse yearlings (mean ± SD; 9 ± 1 mo) were randomly assigned to receive either no supplementation (CON; n = 8) or 21 g/d Saccharomyces cerevisiae fermentation product (10.5 g/feeding twice daily; SCFP; n = 10) top dressed on a basal diet of custom-formulated grain, as well as ad libitum Coastal bermudagrass hay. After 8 wk of dietary treatments, horses underwent a 2-h submaximal exercise test (SET) on a free-stall mechanical exerciser. Serum was collected before dietary treatment supplementation (wk 0), and at wk 8 pre-SET, and 0, 1, and 6 h post-SET, and analyzed for concentrations of cortisol and serum amyloid A (SAA) by commercial ELISA, and for cytokine concentrations by commercial bead-based ELISA. Data were analyzed using linear models with repeated measures in SAS v9.4. From wk 0 to 8 (pre-SET), serum cortisol decreased (P = 0.01) and SAA did not change but neither were affected by diet. Serum concentrations of all cytokines decreased from wk 0 to 8 (P ≤ 0.008), but granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and interleukin-8 (IL-8) decreased to a greater extent in CON than in SCFP horses (P ≤ 0.003). In response to the wk 8 SET, serum cortisol increased in all horses (P &lt; 0.0001), but returned to pre-SET levels by 1 h post-SET in horses receiving SCFP. At 6 h post-SET, cortisol concentrations in CON horses returned to pre-SET concentrations, while cortisol declined further in SCFP horses to below pre-SET levels (P = 0.0002) and lower than CON (P = 0.003) at that time point. Serum amyloid A increased at 6 h post-SET in CON (P &lt; 0.0001) but was unchanged through 6 h in SCFP horses. All cytokines except G-CSF increased in response to the SET (P &lt; 0.0001), but showed differing response patterns. Concentrations of IL-1β, IL-6, and tumor necrosis factor alpha (TNFα) were lesser (P ≤ 0.05), and concentrations of G-CSF and IL-18 tended to be lesser (P ≤ 0.09) in SCFP compared to CON horses throughout recovery from the SET. In summary, 8 wk of dietary supplementation with 21 g/d of SCFP may mitigate cellular stress following a single, prolonged submaximal exercise bout in young horses.