Effect of exercise training, selenium and vitamin E on some free radical scavengers in horses (Equus caballus)

Identification of mulberry leaf flavonoids and evaluating their protective effects on H2O2-induced oxidative damage in equine skeletal muscle satellite cells

Introduction: Horses are susceptible to oxidative stress during strenuous endurance exercise, leading to muscle fatigue and damage. Mulberry leaf flavonoids (MLFs) possess significant antioxidant properties. However, the antioxidant efficacy of MLFs can be influenced by the extraction process, and their impact on H2O2-induced oxidative stress in equine skeletal muscle satellite cells (ESMCs) remains unexplored. Methods: Our study employed three extraction methods to obtain MLFs: ultrasound-assisted extraction (CEP), purification with AB-8 macroporous resin (RP), and n-butanol extraction (NB-EP). We assessed the protective effects of these MLFs on H2O2-induced oxidative stress in ESMCs and analyzed the MLF components using metabolomics. Results: The results revealed that pre-treatment with MLFs dose-dependently protected ESMCs against H2O2-induced oxidative stress. The most effective concentrations were 0.8 mg/mL of CEP, 0.6 mg/mL of RP, and 0.6 mg/mL of NB-EP, significantly enhancing EMSC viability (p < 0.05). These optimized MLF concentrations promoted the GSH-Px, SOD and T-AOC activities (p < 0.05), while reducing MDA production (p < 0.05) in H2O2-induced ESMCs. Furthermore, these MLFs enhanced the gene expression, including Nrf2 and its downstream regulatory genes (TrxR1, GPX1, GPX3, SOD1, and SOD2) (p < 0.05). In terms of mitochondrial function, ESMCs pre-treated with MLFs exhibited higher basal respiration, spare respiratory capacity, maximal respiration, ATP-linked respiration compared to H2O2-induced ESMCs (p < 0.05). Additionally, MLFs enhanced cellular basal glycolysis, glycolytic reserve, and maximal glycolytic capacity (p < 0.05). Metabolomics analysis results revealed significant differences in mulberrin, kaempferol 3-O-glucoside [X-Mal], neohesperidin, dihydrokaempferol, and isobavachalcone among the three extraction processes (p < 0.05). Discussion: Our study revealed that MLFs enhance antioxidant enzyme activity, alleviate oxidative damage in ESMCs through the activation of the Nrf2 pathway, and improve mitochondrial respiration and cell energy metabolism. Additionally, we identified five potential antioxidant flavonoid compounds, suggesting their potential incorporation into the equine diet as a strategy to alleviate exercise-induced oxidative stress.

New Pathophysiological Insights from Serum Proteome Profiling in Equine Atypical Myopathy

Equine atypical myopathy (AM) is a severe environmental intoxication linked to the ingestion of protoxins contained in seeds and seedlings of the sycamore maple (Acer pseudoplatanus) in Europe. The toxic metabolites cause a frequently fatal rhabdomyolysis syndrome in grazing horses. Since these toxic metabolites can also be present in cograzing horses, it is still unclear as to why, in a similar environmental context, some horses show signs of AM, whereas others remain clinically healthy. Label-free proteomic analyses on the serum of 26 diseased AM, 23 cograzers, and 11 control horses were performed to provide insights into biological processes and pathways. A total of 43 and 44 differentially abundant proteins between "AM vs cograzing horses" and "AM vs control horses" were found. Disease-linked changes in the proteome of different groups were found to correlate with detected amounts of toxins, and principal component analyses were performed to identify the 29 proteins representing a robust AM signature. Among the pathway-specific changes, the glycolysis/gluconeogenesis pathway, the coagulation/complement cascade, and the biosynthesis of amino acids were affected. Sycamore maple poisoning results in a combination of inflammation, oxidative stress, and impaired lipid metabolism, which is trying to be counteracted by enhanced glycolysis.

Relationship Between Selenium, Copper, Zinc and Their Biomarkers in Blood and Skeletal Muscle Tissue in Adult Horses From Southern Chile

Microminerals are necessary for all bodily functions. In animal species, selenium (Se), copper (Cu) and zinc (Zn) all form part of antioxidant enzymes. Micromineral deficiencies, particularly Se, are well recognized in large animal species in Chile. Glutathion peroxidase (GPx) is a widely used biomarker for Se nutritional status and to diagnose Se deficiency in horses. Superoxide dismutase (SOD) is a Cu and Zn-dependant antioxidant enzyme, although it is not commonly used as a proxy for the nutritional status of these minerals. Ceruloplasmin (CP) is used as a biomarker of Cu nutritional status. This study´s objective was to explore correlation between said minerals and biomarkers in adult horses from southern Chile. Se, Cu, Zn, GPx, SOD, and CP were measured in whole blood of a group of 32 adult horses (5-15 years old). Further, a second group of 14 adult horses (5-15 years old) underwent gluteal muscle biopsies to determine Cu, Zn, GPx, and SOD. Correlations were determined by means of Pearson´s r coefficient. Significant correlations were found for blood GPx and Se (r = 0.79), blood GPx and SOD (r = -0.6), muscular GPx and SOD (r = 0.78), and Cu and CP (r = 0.48). These results confirm previously described strong association between blood GPx and Se in horses, validating the former´s use as a diagnostic proxy of Se deficiency in Chilean horses, and suggest significant interactions between GPx and SOD in blood and muscle tissue.

Innovative Blood Antioxidant Test in Standardbred Trotter Horses

In athletic horses, prolonged and intense training gives rise to an imbalance between the production of free radicals and antioxidant molecules, leading to oxidative stress. Considering the relation between exercise and oxidative stress in horses, the present work aims to validate the Kit Radicaux Libres (KRL) test as a tool to verify the influence of taming, training and racing on the total blood antioxidant activity and some haematochemical parameters. Five Italian Standardbred racehorses (two males and three females, aged 12 ± 1 months) from the same training center were selected and monitored upon arrival and during the following year until the racing season. Blood samples were obtained at different timepoints, corresponding to different steps of training. The data showed that KRL values were higher (p < 0.001) before the beginning of the taming period and at 60 days of taming, compared with the training and racing periods; additionally, the total protein value was affected by the training program, whereas no effects of training on muscle enzymes were detected. These results confirm that exercise plays a role in the production of free radicals and show that the KRL test may represent a valid method to determine oxidative stress in athletic horses.

A Fibre- vs. cereal grain-based diet: Which is better for horse welfare? Effects on intestinal permeability, muscle characteristics and oxidative status in horses reared for meat production

Horses reared for meat production are fed high amounts of cereal grains in comparison with horses raised for other purposes. Such feeding practice may lead to risk of poor welfare consequences. The aim of this study was to investigate the effects of two feeding practices on selected metabolic parameters and production aspects. Nineteen Bardigiano horses, 14.3 ± 0.7 months of age, were randomly assigned to two groups-one fed with high amounts of cereal grains (HCG; n = 9; 43% hay plus 57% cereal grain-based pelleted feed) vs. one fed with high amounts of fibre (HFG; n = 10; 70% hay plus 30% pelleted fibrous feed)-for 129 days. At slaught on abattoir, biological and tissue samples were collected to evaluate the microbiological contamination of mesenteric lymph nodes and liver; selected meat quality traits (chemical composition and fatty acid profile of the Longissimus thoracis et lumborum muscle); and the oxidative status of the horse. A linear mixed model was used: dietary treatment and sex were fixed effects and their interaction analysed on production and metabolic parameters as dependent variables. Results showed an increased intestinal permeability in the horses fed HCG compared to HFG, according to the significant increased total mesophilic aerobic bacteria counts in mesenteric lymph nodes (p = 0.04) and liver samples (p = 0.05). Horses in HCG showed increased muscle pH (p = 0.02), lighter muscle colour (L) (p = 0.01), increased intramuscular fat concentrations (p = 0.03), increased muscle glutathione peroxidase and superoxide dismutase activities (p = 0.01 and p = 0.03, respectively). Moreover, horses in HCG had lower muscle water holding capacity at interaction with sex (p = 0.03, lower in female), lower muscle protein content (p = 0.01), lower concentration of muscle PUFAs (p = 0.05) and lower plasma catalase activities (p = 0.05). Our results showed that feeding a high cereal grains diet can have global effects on horse physiology, and thus represents a threat for their welfare.

Effects of Vitamin E and Coenzyme Q10 Supplementation on Oxidative Stress Parameters in Untrained Leisure Horses Subjected to Acute Moderate Exercise

The effects of antioxidant supplements on exercise-induced oxidative stress have not been investigated in untrained leisure horses. We investigated the effects of 14-day supplementation with vitamin E (1.8 IU/kg/day), coenzyme Q₁₀ (CoQ₁₀; ubiquinone; 800 mg/day), and a combination of both (the same doses as in mono-supplementation) on the blood levels of CoQ₁₀, vitamin E, and oxidative stress parameters in untrained leisure horses subjected to acute moderate exercise. Correlations between lipid peroxidation and muscle enzyme leakage were also determined. Forty client-owned horses were included in the study, with 10 horses in each of the antioxidant and placebo (paraffin oil) groups. Blood parameters were measured before supplementation, before and immediately after exercise, and after 24 h of rest. The differences in individual parameters between blood collection times and groups were analysed with linear mixed models (p ˂ 0.05). None of the supplemented antioxidants affected vitamin E and CoQ₁₀ concentrations, oxidative stress parameters, or serum muscle enzymes. Lipid peroxidation occurred in horses supplemented with placebo and CoQ₁₀ but not in horses supplemented with vitamin E or the combination of both antioxidants. These results suggest that vitamin E alone or in combination with CoQ₁₀ prevented lipid peroxidation in untrained leisure horses subjected to acute moderate exercise.

Dietary conjugated linoleic acid supplementation alters skeletal muscle mitochondria and antioxidant status in young horses

Conjugated linoleic acid (CLA) improves oxidative stress and mitochondrial biogenesis in various species but has not been thoroughly investigated in horses. We collected blood and muscle samples from lightly exercising horses before and 6 and 12 wk after receiving either soybean oil (CON; n = 5) or CLA (CLA; n = 5) supplementation. Samples were analyzed for markers of mitochondrial characteristics, antioxidant status, oxidative stress, and muscle damage. Data were analyzed using a linear model with repeated measures. In the triceps brachii (TB), citrate synthase (CS) activity was higher in CON than CLA horses (P = 0.003) but was unaffected by diet in the gluteus medius (GM). Integrative (relative to mg protein) cytochrome c oxidase (CCO) activity was higher in TB than the GM (P < 0.0001), while intrinsic (relative to CS) CCO was lower in the TB than the GM (P = 0.02) and tended to be lower in CON than CLA horses (P = 0.06). Neither CS nor integrative CCO activities were affected by time. In the GM, superoxide dismutase activity tended to increase in CON through week 12 (P = 0.10). Over both muscle groups, glutathione peroxidase activity tended to be higher in CON compared with CLA at week 12 (P = 0.06). Malondialdehyde was higher in the TB than the GM (P = 0.0004) but was unaffected by diet, while serum creatine kinase activity tended to be lower in CLA than CON horses (P = 0.07). These results suggest that CLA supplementation may lead to mitochondrial adaptations and prevent myofiber perturbation in skeletal muscle of young, lightly exercised horses.

Form of Vitamin E Supplementation Affects Oxidative and Inflammatory Response in Exercising Horses

Vitamin E is an essential antioxidant that may benefit athletes by reducing oxidative stress and influencing cytokine expression. Supplements can be derived from natural or manufactured synthetic sources. This study aimed to determine (1) if supplemental vitamin E is beneficial to exercising horses and (2) if there is a benefit of natural versus synthetic vitamin E. After 2 weeks on the control diet (vitamin E-deficient grain and hay), 18 horses were divided into three groups and fed the control diet plus (1) 1000 IU/d synthetic α-tocopherol (SYN-L), (2) 4000 IU/d synthetic α-tocopherol (SYN-H), or (3) 4000 IU/d RRR-α-tocopherol (natural source [NAT]). On day 7, horses began a 6-week training protocol, with standard exercise tests (SETs) performed before and after the 6-week protocol. Venous blood samples were collected on days 0, 7, 29, and 49. Horses fed NAT had higher α-tocopherol (P < .05) at post-SET1 through post-SET2. Plasma thiobarbituric acid-reactive substance levels were lower in NAT versus SYN-L horses after SET2 (P = .02). Serum aspartate aminotransferase was lower after exercise in NAT horses versus SYN-L and SYN-H (P = .02), and less reduction in stride duration was seen after exercise in NAT as compared with SYN-L and SYN-H (P = .02). Gene expression of tumor necrosis factor α was lower in NAT compared with SYN-H (P = .01) but not SYN-L. In conclusion, feeding higher levels of natural vitamin E source resulted in higher serum α-tocopherol levels as well as some improvement in oxidative and inflammatory response and improved functional outcomes in response to an exercise test.

Expression Quantitative Trait Loci in Equine Skeletal Muscle Reveals Heritable Variation in Metabolism and the Training Responsive Transcriptome

While over ten thousand genetic loci have been associated with phenotypic traits and inherited diseases in genome-wide association studies, in most cases only a relatively small proportion of the trait heritability is explained and biological mechanisms underpinning these traits have not been clearly identified. Expression quantitative trait loci (eQTL) are subsets of genomic loci shown experimentally to influence gene expression. Since gene expression is one of the primary determinants of phenotype, the identification of eQTL may reveal biologically relevant loci and provide functional links between genomic variants, gene expression and ultimately phenotype. Skeletal muscle (gluteus medius) gene expression was quantified by RNA-seq for 111 Thoroughbreds (47 male, 64 female) in race training at a single training establishment sampled at two time-points: at rest (n = 92) and four hours after high-intensity exercise (n = 77); n = 60 were sampled at both time points. Genotypes were generated from the Illumina Equine SNP70 BeadChip. Applying a False Discovery Rate (FDR) corrected P-value threshold (P_FDR < 0.05), association tests identified 3,583 cis-eQTL associated with expression of 1,456 genes at rest; 4,992 cis-eQTL associated with the expression of 1,922 genes post-exercise; 1,703 trans-eQTL associated with 563 genes at rest; and 1,219 trans-eQTL associated with 425 genes post-exercise. The gene with the highest cis-eQTL association at both time-points was the endosome-associated-trafficking regulator 1 gene (ENTR1; Rest: P_FDR = 3.81 × 10^-27, Post-exercise: P_FDR = 1.66 × 10^-24), which has a potential role in the transcriptional regulation of the solute carrier family 2 member 1 glucose transporter protein (SLC2A1). Functional analysis of genes with significant eQTL revealed significant enrichment for cofactor metabolic processes. These results suggest heritable variation in genomic elements such as regulatory sequences (e.g. gene promoters, enhancers, silencers), microRNA and transcription factor genes, which are associated with metabolic function and may have roles in determining end-point muscle and athletic performance phenotypes in Thoroughbred horses. The incorporation of the eQTL identified with genome and transcriptome-wide association may reveal useful biological links between genetic variants and their impact on traits of interest, such as elite racing performance and adaptation to training.

Evaluation of Biological Indicators of Fatigue and Muscle Damage in Arabian Horses After Race

The aim of this study was to assay changes in blood biochemical parameters that resulted from exercise-induced muscle fatigue in horses participating in the two races (1,250 and 1,400 meters). Six male Arabian horses (3 to 6 years old) were used in this study. Blood samples were collected at time intervals including 1 hour before the race, immediately after the race, 1 and 24 hours after the end of race. Catalase (CAT), superoxide dismutase, glutathione peroxidase (GPX) activities, the blood level of malondialdehyde, protein carbonyl, and total antioxidant capacity (TAC) were measured, as well as muscle damage biomarkers including aspartate aminotransferase (AST), lactate dehydrogenase (LDH), creatine kinase (CK) activities, and myoglobin were measured. The results showed that CAT activity and plasma TAC in the horse increased immediately after the race and then gradually decreased. The highest GPX activity in red blood cells was recorded 1 hour before the start of the race. Superoxide dismutase showed an incremental pattern after the race. Immediately after the race, there was a significant increase in the plasma levels of AST, which continued until 1 hour after the race. The activity of LDH and CK reached its highest value 1 hour after the race. According to our findings, it can be concluded that the horses were tired and antioxidant enzymes altered under fatigue conditions. Muscle damage biomarkers have increased, but these increases were in their natural ranges and did not indicate muscle damage in horses.

Submaximal exercise training, more than dietary selenium supplementation, improves antioxidant status and ameliorates exercise-induced oxidative damage to skeletal muscle in young equine athletes

Exercise is associated with increased production of reactive oxygen species (ROS) as metabolism is upregulated to fuel muscle activity. If antioxidant systems become overwhelmed, ROS can negatively affect health and performance. Adaptation to exercise through regular training has been shown to improve defense against oxidative insult. Given selenium's role as an antioxidant, we hypothesized that increased Se intake would further enhance skeletal muscle adaptations to training. Quarter Horse yearlings (18 ± 0.2 mo; 402 ± 10 kg) were randomly assigned to receive either 0.1 or 0.3 mg Se/kg DM and placed in either an untrained or a trained (30 min walk-trot-canter, 4 d/wk) group for 14 wk. Phase 1 (wk 1 to 8) consisted of 4 treatments: trained and fed 0.1 mg Se/kg DM through wk 14 (CON-TR; n = 10), trained and fed 0.3 mg Se/kg DM through wk 14 (HIGH-TR; n = 10), untrained and fed 0.1 mg Se/kg DM through wk 14 (CON-UN; n = 5), or untrained and fed 0.3 mg Se/kg DM through wk 14 (HIGH-UN; n = 5). During Phase 2 (wk 9 to 14), dietary Se level in half of the trained horses was reversed, resulting in 6 treatments: CON-TR (n = 5), trained and fed 0.1 mg/kg Se in Phase 1 and then switched to 0.3 mg/kg Se for Phase 2 (ADD-TR; n = 5), trained and fed 0.3 mg/kg Se in Phase 1 and then switched to 0.1 mg/kg Se for Phase 2 (DROP-TR; n = 5), HIGH-TR (n = 5), CON-UN (n = 5), or HIGH-UN (n = 5). All horses underwent a 120-min submaximal exercise test (SET) at the end of Phase 1 (SET 1) and 2 (SET 2). Blood samples and biopsies from the middle gluteal muscle were collected before and after each phase of the study and in response to each SET and analyzed for markers of oxidative damage and antioxidant enzyme activity. In both phases, serum Se was higher (P < 0.0001) when horses received a diet with 0.3 than 0.1 mg Se/kg DM. Throughout the 14-wk study, resting activities of muscle glutathione peroxidase (GPx; P = 0.004) and superoxide dismutase (SOD; P = 0.06) were greater in trained horses than in untrained horses. In response to SET 1, serum creatine kinase (CK) activity was lower in trained horses than in untrained horses (P < 0.0001), indicating less muscle damage, but plasma lipid hydroperoxides (LPO) and muscle GPx and SOD activities were unaffected by training or Se. In response to SET 2, trained horses had greater muscle SOD activity (P = 0.0002) and lower serum CK activity (P = 0.003) and showed a trend for lower plasma LPO (P = 0.09) and muscle malondialdehyde (P = 0.09) than untrained horses. Muscle GPx activity did not change in response to SET 2 and was unaffected by training or Se. Results indicate that exercise training lessens muscle damage and improves antioxidant defense following an acute bout of prolonged exercise and was not further enhanced by feeding Se above the NRC requirement.

Endurance exercise causes adverse changes in some hematological and physiobiochemical indices in ponies under high altitude stress condition

The ponies have immense relevance for logistic support for civil population and troops in hilly and high altitude areas. There is no information on specific biomarkers of endurance performance under high altitude stress condition, which could be supportive in the identification of elite ponies for deployment at high altitude. Therefore, the present study was conducted to evaluate the physiological responses, hematological, biochemical, metabolic, and antioxidant biomarker during endurance exercise in ponies at high altitude. For this study, total 5 mares were put on endurance exercise at 4–6 m/sec speed for 30 min on 30 m track situated at 3,500 m altitude for 28 days period. The result showed a significant change in physiological responses, and some hematological, biochemical, metabolic and antioxidant parameters viz. glutathione peroxidase, creatinine kinase-MB, lactic acid, total protein, glucose, hexokinase, cortisol, and interleukin-6 level at different phase of endurance exercise. In conclusion, this study showed the alteration in physiological responses and some hematological and physio-biochemical metabolic parameters during the endurance exercise. Hence, these parameters could be considered as biomarkers for evaluation of endurance performance in ponies at high altitude before putting them under load carrying deployment.

Effects of age and exercise on inflammatory cytokines, HSP70 and HSP90 gene expression and protein content in Standardbred horses

We hypothesised that the cortisol response to acute exercise, markers of oxidative stress, expression of inflammatory cytokines, heat shock protein (HSP)70 and HSP90 expression in whole blood and skeletal muscle, and HSP70 and HSP90 protein concentrations in skeletal muscle are altered by age and in response to acute submaximal exercise in horses. Young (n=6; 5.5±2.8 year) and aged (n=6; 22.6±2.25 year) unconditioned Standardbred mares underwent an acute submaximal exercise test. Blood samples were collected and analysed for plasma cortisol and malondialdehyde (MDA) concentrations, and for cytokine and HSP gene expression pre- and post-exercise. Gluteus medius biopsies were obtained for analysis of cytokine and HSP gene expression pre- and at 0, 4, 24 and 48 h post-exercise. Data were analysed for main effects using a two-way ANOVA for repeated measures. Post-hoc comparisons of means were conducted using Student-Neuman-Keuls for pair-wise multiple comparisons where appropriate. Acute submaximal exercise increased plasma cortisol concentration in both young and aged mares, and the duration of the post-exercise rise in cortisol was altered in aged horses. Plasma MDA concentration and expression of tumour necrosis factor-α (TNF-α) and interleukin (IL)-6 were unchanged in blood and muscle. Exercise increased IL-1β expression in whole blood of young and aged mares, with young mares having greater exercise-induced expression at 2 (P<0.001) and 4 (P=0.019) h post-exercise. Both young and aged horses had increased HSP70 expression in whole blood following acute exercise, with young horses exhibiting 3-fold greater HSP70 expression than aged mares at 2 h post-exercise. HSP90 expression in whole blood following exercise was increased only in young horses. Both young and aged horses had increased HSP90 expression in skeletal muscle following exercise, but there was no difference due to age. However, the timing of HSP70 expression was different between young and aged horses. The age-related changes in cortisol and IL-1β expression following acute submaximal exercise can have implications for energy homeostasis and the adaption to such disturbances at a cellular and whole animal level. Quantification of HSP expression in whole blood may be a useful biomarker, with implications for cellular adaptation and survival in aged horses.

Equine skeletal muscle adaptations to exercise and training: evidence of differential regulation of autophagosomal and mitochondrial components

BACKGROUND

A single bout of exercise induces changes in gene expression in skeletal muscle. Regular exercise results in an adaptive response involving changes in muscle architecture and biochemistry, and is an effective way to manage and prevent common human diseases such as obesity, cardiovascular disorders and type II diabetes. However, the biomolecular mechanisms underlying such responses still need to be fully elucidated. Here we performed a transcriptome-wide analysis of skeletal muscle tissue in a large cohort of untrained Thoroughbred horses (n = 51) before and after a bout of high-intensity exercise and again after an extended period of training. We hypothesized that regular high-intensity exercise training primes the transcriptome for the demands of high-intensity exercise.

RESULTS

An extensive set of genes was observed to be significantly differentially regulated in response to a single bout of high-intensity exercise in the untrained cohort (3241 genes) and following multiple bouts of high-intensity exercise training over a six-month period (3405 genes). Approximately one-third of these genes (1025) and several biological processes related to energy metabolism were common to both the exercise and training responses. We then developed a novel network-based computational analysis pipeline to test the hypothesis that these transcriptional changes also influence the contextual molecular interactome and its dynamics in response to exercise and training. The contextual network analysis identified several important hub genes, including the autophagosomal-related gene GABARAPL1, and dynamic functional modules, including those enriched for mitochondrial respiratory chain complexes I and V, that were differentially regulated and had their putative interactions 're-wired' in the exercise and/or training responses.

CONCLUSION

Here we have generated for the first time, a comprehensive set of genes that are differentially expressed in Thoroughbred skeletal muscle in response to both exercise and training. These data indicate that consecutive bouts of high-intensity exercise result in a priming of the skeletal muscle transcriptome for the demands of the next exercise bout. Furthermore, this may also lead to an extensive 're-wiring' of the molecular interactome in both exercise and training and include key genes and functional modules related to autophagy and the mitochondrion.

Antioxidant and haematological biomarkers in different groups of horses supplemented with polyunsaturated oil and vitamin E

Oxidative stress has been correlated with pathologies that impair the performance of athlete horses. The aim of this study was to assess the effects of supplementation with a mixture of polyunsaturated oil and vitamin E on the antioxidant and haematological biomarkers of horses. Horses under maintenance care (n = 6) and horses in training (n = 10) received 100 and 300 ml of the oil mixture respectively. Supplementation was provided for a period of 8 weeks, together with isocaloric inclusion. Blood samples were collected at three time periods (pretest, after 4 weeks and after 8 weeks) to analyse the following: the red blood cell count (RBCc); haemoglobin (Hb); haematocrit (HT); leucocytes; lymphocytes; platelets; the mean corpuscular volume (MCV); the mean corpuscular haemoglobin concentration (MCHC); the standard deviation of the red blood cell distribution width (RDW-SD); the coefficient of variation of the red blood cell distribution width (RDW-CV); glutathione peroxidase (GPx); superoxide dismutase (SOD); uric acid (UrAc); total plasma proteins (TPP); and creatine kinase (CK). After the 8 weeks of supplementation, animals under maintenance care exhibited significant increases in SOD, UrAc, the white blood cell count (WBCc), the RDW-SD and the RDW-CV (p < 0.05). The animals in training exhibited increases in GPx, SOD and UrAc (p < 0.05). In conclusion, supplementation with polyunsaturated oil and vitamin E increases blood antioxidants among animals under maintenance and in training, with different trends, while contributing to the fight against oxidative stress in each group analysed.

Efeito da suplementação com vitamina E sobre os metabolismos oxidativo e cardíaco em equinos submetidos a exercício de alta intensidade

A suplementação antioxidante visa prevenir os danos oxidativos induzidos pelo exercício físico em diversos tecidos, como o miocárdio. Nesse contexto, este estudo objetivou avaliar os marcadores cardíacos e a lipoperoxidação em equinos no teste de exercício de rápida aceleração e curta duração (TRA), em esteira de alta velocidade, antes e após a suplementação com vitamina E. Para tanto, foram utilizados 10 equinos sem treinamento, que realizaram o primeiro TRA (TRA1) com carga de trabalho fundamentada no consumo máximo de oxigênio individual (VO2max) e que induziu a concentração de lactato maior que 4mmol/L, sendo considerado predominantemente anaeróbico. Em seguida, os equinos receberam vitamina E (dl-alfa-tocoferol) na dose de 1.000UI/dia, por via oral, durante 52 dias, e, posteriormente, realizaram um segundo TRA (TRA2) com o mesmo protocolo de TRA1. As amostras de sangue foram colhidas nos momentos antes do exercício, imediatamente após o término do teste e em 1h, 3h, 6h, 12h e 24h subsequentes. Determinou-se o malondialdeído (MDA) plasmático como índice de lipoperoxidação, e as concentrações séricas de troponina I cardíaca (cTnI), isoenzima MB da creatinoquinase (CK-MB) e mioglobina, como marcadores cardíacos. Como efeito do exercício, observou-se aumento discreto de MDA, de cTnI e de CK-MB, sendo significativo apenas para CK-MB. A suplementação foi capaz de amenizar a produção das espécies reativas de oxigênio, evidenciada pela menor concentração de MDA em TRA2, em 24h, além de causar um efeito protetor no miocárdio, devido ao menor valor de cTnI em 6h no TRA2 em relação ao TRA1. Não houve grandes alterações na concentração de mioglobina. Concluiu-se que o exercício de alta intensidade promoveu estresse no miocárdio nos equinos avaliados, bem como houve efeito benéfico da vitamina E na proteção miocárdica e sobre a lipoperoxidação.

Effect of Procedure Parameters on the Antioxidant Property of Perilla Frutescens Leave Extracts

The aim of this study was to determine the procedure parameters, including drying, extracting and pH on the antioxidant activity and antioxidative compounds in Perilla frutescens leaves. The extraction of antioxidants from Perilla frutescens leaves is studied considering different drying and extracting procedures to investigate the selectivity of the process. The radical-scavenging activity (RSA) of 1, 1-diphenyl-2-picrylhydrazyl (DPPH) and the determination of the total phenolic content are applied to evaluate the antioxidant activity and antioxidative compounds of the Perilla frutescens leave extracts. The highest antioxidant activity is observed for the extract obtained by freeze drying, extracting by ultrasound with 80% methanol adjusted at pH 4.The antioxidant compound extraction yield was also the highest at these extraction conditions. The total phenol contents among the Perilla frutescens leave extracts produced by different drying procedures were similar, while the antioxidant activities were different This concluding that the amount of phenolic compounds extracted was similar but the type and probable structure of the phenolic changed during heat-drying procedure providing in this way. Our study showed that proper process technology could ultimately extract compounds potentially effective against diseases related to free radical oxidation.

Oxidative metabolism and muscle biochemical profile of polo horses supplemented with an ADE vitamin complex

Horses used for the game of polo experience abrupt and frequent changes in exercise intensity. To meet this variable energy demand, the horses use both aerobic and anaerobic pathways in varying proportions and intensities. In this context, there must be a balance between the formation of reactive oxygen species (ROS) and the action of antioxidants to prevent oxidative stress and its consequences. The effect of supplementation with an ADE vitamin complex on oxidative metabolism was evaluated in 18 crossbred horses randomly divided between a treated group (TG) and a control group (CG). The TG animals received the ADE vitamin complex (1mL/50 kg of body weight) by deep intramuscular injection at 30 and 15 days before the game. The CG horses received 10ml of saline by the same administration route and schedule. During the polo match, the animals played for a total of 7.5 min. Blood samples were collected on the same days as the treatments were administered, and immediately before and at 15, 90 and 180 minutes after the game. The concentrations of creatine phosphokinase (CK), lactate dehydrogenase (LDH), lactate, glucose, aspartate aminotransferase (AST), glutathione (GSH), superoxide dismutase (SOD) and malondialdehyde (MDA) were measured in the blood samples. After the game, the TG demonstrated higher levels of AST, lactate and glucose than the CG, suggesting more efficient energy use by the treated animals. The higher GSH and lower lactate levels in the TG before the game suggest the presence of a greater antioxidant supply in the treated animals. The maintenance of the MDA levels indicates that neither of the groups exhibited oxidative stress.

Effects of chestnut tannins on performance and antioxidative status of transition dairy cows

This study was conducted to evaluate the effects of chestnut tannins (CT) on performance and antioxidative status of transition dairy cows. Twenty multiparous Chinese Holstein cows in late gestation were paired according to expected calving date and randomly assigned either to a diet supplemented with CT (CNT, 10 g of CT/kg of diet, dry matter basis) or to an unsupplemented control (CON) diet from 3 wk prepartum to 3 wk postpartum. Blood samples were taken on d -21, 1, 7, and 21 relative to calving for analysis of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), total antioxidant capacity (T-AOC), and malondialdehyde (MDA). Liver samples were taken by puncture biopsy on d 1 and 21 relative to calving for analysis of SOD, GSH-Px, and MDA. Data were analyzed for a completely randomized block design with repeated measures. The addition of CT had no significant effects on dry matter intake, body weight, body condition score, milk yield, 3.5% fat-corrected milk yield, and milk composition but did decrease milk MDA and somatic cell score in transition dairy cows. Dry matter intake decreased from d -21 to 0 and increased from d 1 to 21 relative to calving across treatments. During the experimental period, body weight and body condition score decreased, whereas milk MDA and somatic cell score increased across treatments. A time effect was also observed for plasma MDA, which peaked on d 1 relative to calving and remained higher than that on d -21 relative to calving across treatments. Addition of CT decreased MDA concentrations in plasma and liver. Neither time nor CT × time effects were observed for SOD and T-AOC in plasma and SOD and GSH-Px in liver; a time effect was observed for plasma GSH-Px, which peaked on d 1 relative to calving and remained higher than those on d -21 relative to calving across treatments. Addition of CT increased SOD, GSH-Px, and T-AOC activities in plasma and SOD and GSH-Px activities in liver. In conclusion, addition of CT might inhibit lipid peroxidation and increase antioxidant enzymes activities in plasma and liver of transition dairy cows. Supplementation of CT may be a feasible means to improve the antioxidative status of transition dairy cows.

Effect of selenium and vitamin C on clinical outcomes, trace element status, and antioxidant enzyme activity in horses with acute and chronic lower airway disease. A randomized clinical trial

Excess production of reactive oxygen species is involved in the pathogenesis of airway disorders in horses. Trace element antioxidants have a beneficial role in oxidant/antioxidant balance. The aim of the present study was to evaluate the effect of a combination of sodium selenite and ascorbic acid on clinical outcome, antioxidant enzymes, and trace elements status in horses with lower airway disease. For this purpose, 40 draft horses with lower airway disease were randomly selected (acute, n = 20; chronic, n = 20). Both acute and chronic cases were randomly allocated into two subgroups (ten each). Groups 1 and 2 were the horses with acute disease, while groups 3 and 4 were chronically ill. For all groups, each horse was administered antibiotic, non-steroidal anti-inflammatory, and mucolytic drug. In addition, groups 2 and 4 were injected with 15 mg/kg sodium selenite and 30 mg/kg ascorbic acid every 24 h for successive 4 weeks. Venous blood samples were obtained from diseased horses on three occasions; at first examination, and at 2 and 4 weeks post-treatment. Clinically, antioxidant supplementation improved the clinical signs with significant decrease (p < 0.05) of the clinical index score in both acute and chronic cases. In supplemented groups compared with non-supplemented, there was a significant increase (p < 0.05) in the levels of copper, zinc, selenium, and iron as well as in the activity of glutathione-S-transferase and catalase. Meanwhile, there was a significant decrease (p < 0.05) in the levels of manganese, malondialdehyde, hydrogen peroxide, and low-density lipoprotein and in the activity of glutathione reductase. The results of the present study indicate that administration of sodium selenite and ascorbic acid may have beneficial effect on clinical outcome and antioxidant balance in horses with acute and chronic lower airway disease.

Semen quality, lipid peroxidation, and seminal plasma antioxidant status in horses with different intensities of physical exercise

The aim of this study was to compare markers of semen quality, sperm membrane damage, and the seminal plasma antioxidant activity in warmblood stallions with and without sport workload stress. Four stallions were used for breeding only (control) and four both for breeding and competition in jumping. Semen samples were collected at 14-day intervals (from June to August) from each stallion (5 ejaculates per stallion). Immediately after sperm collection, a conventional examination of the ejaculate was processed. Catalytic activities of enzymes aspartate aminotransferase, alanin aminotransferase, glutathione peroxidase, superoxide dismutase and indicator of lipoperoxidation - F2α isoprostanes were measured in samples of seminal plasma. Contrary to basic semen quality indicators, the values of seminal plasma pH, aspartate aminotransferase and alanin aminotransferase were significantly (P < 0.05) impaired in the physically stressed stallions. Also, the level of F2α isoprostanes and the activity of superoxide dismutase were significantly (P < 0.05) increased by stress. The antioxidant activities of superoxide dismutase and glutathion peroxidase increased during the monitored period and reflected changes in F2α isoprostane concentration. We can conclude that even the conventional basic sperm indicators stay within the reference ranges of the biochemical indicators of seminal plasma such as pH or AST/ALT activity may be negatively influenced by sport workload stress. Increased concentrations of F2α isoprostanes indicate that lipoperoxidation can be a mechanism of cell membrane destabilization, which is counteracted by an increase of antioxidant enzyme activities. This is the first report of oxidative stress symptoms in normospermic equine semen in relation to stallion sport workload.

Effect of Treadmill Exercise and Hydrogen-rich Water Intake on Serum Oxidative and Anti-oxidative Metabolites in Serum of Thoroughbred Horses

The present study aimed to clarify changes of oxidative stress and antioxidative functions in treadmill-exercised Thoroughbred horses (n=5, 3 to 7 years old), using recently developed techniques for measurement of serum d-ROMs for oxidative stress, and BAP for antioxidative markers. Also, the effect of nasogastric administration of hydrogen-rich water (HW) or placebo water preceding the treadmill exercise on these parameters was examined. Each horse was subjected to a maximum level of treadmill exercise in which the horses were exhausted at an average speed of 13.2 ± 0.84 m/sec. Blood samples were taken 4 times, immediately before the intake of HW or placebo water at 30 min preceding the treadmill exercise, immediately before the exercise (pre-exercise), immediately after the exercise (post-exercise) and at 30 min following the exercise. In all horses, both d-ROMs and BAP values significantly increased at post-exercise. The increase in d-ROMs tended to be lower in the HW trial, as compared to the placebo trial at pre-exercise. The increase in BAP was considerable at approximately 150% of the pre-exercise values in both the HW and placebo treatment trials. The BAP/d-ROMs ratio was significantly elevated at post-exercise in both treatment trials, while a significant elevation was also observed at pre-exercise in the HW trial. BAP, d-ROM, and the BAP/d-ROM ratio tended to decline at 30 min after the exercise, except BAP and BAP/d-ROMs in the placebo trial. These results demonstrate that the marked elevation of oxidative stress and anitioxidative functions occurred simultaneously in the intensively exercised horses, and suggest a possibility that HW has some antioxidative efficacy.

Short- and long-term effect of oral administration of micellized natural vitamin E (D-α-tocopherol) on oxidative status in race horses under intense training

This study tested the effect of micellized vitamin E (D-α-tocopherol; 1,400 IU/d) administered 12 and 1 h orally before training for 1 d (ST-VitE) or 8 d (LT-VitE) compared with an unsupplemented control (CONTROL) on plasma α-tocopherol, thiobarbithuric acid-reactive substances (TBARS), total glutathione (GSHt), and trolox equivalent antioxidant capacity (TEAC) in 10 race horses. Different sampling times [immediately before training (BEF) and after intense training (END) or 8 h after recovery (+8h)] were investigated. Plasma α-tocopherol concentration was greater in the ST-VitE group than the CONTROL group at +8h (P < 0.05). Natural vitamin E supplementation increased plasma α-tocopherol (P < 0.001) in the LT-VitE group by approximately 1.6-fold at BEF, END, and +8h. In all groups, TBARS tended to be slightly greater (P = 0.087) immediately after training when compared with values BEF or +8h and the lowest TBARS values were observed at +8h in LT-VitE. Vitamin E supplementation did not affect the GSHt concentrations at BEF, END, or +8h. The TEAC values were modified by the vitamin E administration (P = 0.010). The greatest TEAC was found in the LT-VitE group at all sampling times and similar concentrations were reached in the ST-VitE group at +8h. The CONTROL group was not able to maintain TEAC after training (P < 0.001), indicating consumption of antioxidants (mainly vitamin E) and consequently oxidative stress because of the antioxidant system being overwhelmed by a reduced antioxidant supply. In conclusion, micellized natural vitamin E at 1,400 IU/d for 8 d efficiently increased plasma α-tocopherol concentration of race horses undergoing intense training conditions and maintained the general oxidative status.

Antioxidant trace elements in serum of draft horses with acute and chronic lower airway disease

The aim of the present study was to evaluate the oxidative stress level and antioxidant trace elements status associated with lower airway disease in draft horses. For this purpose, venous blood samples were obtained from draft horses exhibiting signs of lower respiratory tract disorders (n = 83) and from control group (n = 20). Serum trace elements including selenium (Se), copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe) were assayed. Serum malondialdehyde (MDA) and low-density lipoprotein (LDL) levels as well as plasma hydrogen peroxides (H₂O₂) concentration and activity of plasma glutathione reductase (GR), glutathione-S-transferase (GST) and catalase (CAT) were measured. There was a significant (p < 0.05) decrease of Se, Cu, Zn, and Fe in diseased horses compared with healthy ones, but the Cu/Zn ratio and Mn were increased (p < 0.05). Se was significantly (p < 0.05) decreased in chronically affected horses compared with acute cases, but Mn was increased (p < 0.05). There was an increase of MDA, LDL, and H₂O₂ levels and GR activity in diseased cases compared with healthy horses. However, there was a significant (p < 0.05) decrease of GST and CAT activity. MDA and LDL levels were increased (p < 0.05) in horses with chronic respiratory disease compared to acute cases, but CAT activity was decreased (p < 0.05). In horses with acute lower airway disease, there was a negative correlation between GR and H₂O₂ (r = -0.458), and LDL and CAT (r = -0.816). However, in chronic disease, a negative correlation was recorded between Se and MDA (r = -0.590). The results of the present study indicate that oxidative stress, with alteration of antioxidant trace element levels, is a feature of respiratory disease in draft horses.

The influence of road transport on the activities of glutathione reductase, glutathione peroxidase, and glutathione-S-transferase in equine erythrocytes

BACKGROUND

Transport of horses may have significant impact on serum biochemical and hematologic analytes and resistance to infection.

OBJECTIVE

The aim of our study was to assess the influence of transport stress on selected enzymatic antioxidants in equine blood.

METHODS

The study was conducted on a group of 60 horses of different breeds and ranging in age from 4 to 10 years. Venous blood was collected immediately before loading horses onto trailers for 8 hours of transport (I), immediately after unloading them from the trailer (II), and after subsequent stall rest for 24 hours (III). Hemolysates of blood were prepared, and hemoglobin (Hb) concentration and activities of the enzymatic antioxidants glutathione reductase (GR), glutathione-S-transferase (GST), and glutathione peroxidase (GPx) were measured. Enzyme activities were expressed as units of activity per gram of hemoglobin.

RESULTS

There were significant decreases in activities (mean ± SD U/g Hb [minimum-maximum]) of GPx between collection times I (36 ± 14 U/g Hb [9-67 U/g Hb]) and III (30 ± 11 U/g Hb [12-51 U/g Hb]) and of GR between collection times I (54 ± 28 U/g Hb [7-117 U/g Hb]) and II (40 ± 23 U/g Hb [12-145 U/g Hb]). There was no significant difference in activities of GR between collection times I and III (50 ± 27 U/g Hb [9-116 U/g Hb]). There were no differences detected in GST activity among the 3 collection times.

CONCLUSION

Road transport has an impact on activities of the antioxidant enzymes GPx and GR, with recovery of GR activity evident by 24 hours post-transport. Decreased activity of these enzymes may be one mechanism for increased susceptibility to infections that are manifest after shipping; alternatively, decreases may indicate utilization as these enzymes work to neutralize increases in reactive oxygen species.

Effect of selenium status on the response of unfit horses to exercise

Exercise is known to increase reactive oxygen species and alter glutathione peroxidase activity (GPx), a selenoenzyme responsible for neutralising hydrogen peroxide. This study evaluated the effect of selenium (Se) status on the response of unfit horses to mild exercise. 25 mature horses received one of four dietary treatments for 29 weeks: low Se (LS, n=6), adequate Se (AS, sodium selenite, n=6), high organic Se (SP; Sel-Plex®, n=7) or high inorganic Se (SS, sodium selenite, n=6). Total dietary Se concentration for LS, AS, SP and SS was 0.06, 0.12, 0.3 and 0.3 mg/kg respectively. Blood samples were collected before and at 0, 4 and 24 h after a 36 min exercise test covering 4.41 km. Blood samples were evaluated for blood GPx, pro-inflammatory cytokine expression, serum malondialdehyde (MDA), creatine kinase (CK), aspartate aminotransferase (AST) and blood pro-inflammatory cytokine expression. Data were analysed as ANOVA with repeated measures. Prior to the exercise test blood Se was higher (P<0.01) for SP and SS than AS and LS. An effect of treatment and treatment×time (P<0.05) existed for GPx. Post-exercise GPx decreased in LS and did not recover by 24 h while remaining unchanged in AS. GPx increased in SP and decreased in SS post-exercise, but both returned to pre-values at 24 h. Serum MDA was elevated at 24 h (P<0.05), but unaffected by treatment. Serum CK and AST were unaffected by Se status (P≯0.05). Pro-inflammatory cytokine expression was unaffected by Se status, although tumour necrosis factor alpha decreased immediately after exercise followed by an increase post-exercise while granzyme B was elevated immediately post-exercise (time, P<0.05). Overall Se status had minimal effects on exercise response in unfit horses. The differences in post-exercise GPx response may warrant further investigation.

Oral supplementation with superoxide dismutase in Standardbred trotters in training: a double-blind placebo-controlled study

REASONS FOR PERFORMING STUDY

Intense physical exercise produces an excess of reactive oxygen species which can disturb the antioxidant/oxidant balance of the horse in training. Several classes of antioxidant dietary compounds have been suggested to provide health benefits and there is evidence that consumption of these products leads to a reduction in the expression of various pro-inflammatory and/or oxidative stress biomarkers. The recent development of a new galenic system allows the oral delivery of the antioxidant enzyme: superoxide dismutase (SOD). This has been developed from a specific melon variety with a particularly high SOD activity.

OBJECTIVES

To study the influence of an oral supplementation with an encapsulated melon rich in SOD on muscular and antioxidant balance variables in a population of Standardbreds in training.

METHODS

Twenty-four Standardbreds in training were paired by age, sex and training level. They were randomly split into 2 groups: SOD group (520 iu/day) and placebo group. At the beginning of the study (T0) and after 30 days (T30) and 60 days (T60) of supplementation, physiological response during a standardised exercise test, plasma muscular enzymes at rest and post exercise (creatine kinase), oxidative stress markers (erythrocyte SOD) and blood resistance to haemolysis (KRL test) were assessed. Analysis of variance of time, treatment and interaction time x treatment was calculated.

RESULTS

Between T0 and T60, in contrast with placebo group, a significant increase in the plasma resistance to haemolysis in the SOD group was observed and it was significantly higher (P < 0.05) in the SOD group than in the placebo group on T60. Between T0 and T60, resting CK remained constant in SOD group whereas a significant increase in plasma CK in the placebo group was observed. On T60, the CK level was significantly lower (P < 0.05) in SOD group than in the placebo group.

CONCLUSIONS

These results suggest that oral SOD supplementation might increase blood resistance to haemolysis and reduce the increase in muscular membrane permeability induced by training.

Aerobic training stimulates growth and promotes disease resistance in Atlantic salmon (Salmo salar)

Improving fish robustness is of utmost relevance to reducing fish losses in farming. Although not previously examined, we hypothesized that aerobic training, as shown for human studies, could strengthen disease resistance in Atlantic salmon (Salmo salar). Thus, we exercised salmon pre-smolts for 6 weeks at two different aerobic training regimes; a continuous intensity training (CT; 0.8bls(-1)) and an interval training (IT; 0.8bl s(-1) 16h and 1.0bl s(-1) 8h) and compared them with untrained controls (C; 0.05bl s(-1)). The effects of endurance training on disease resistance were evaluated using an IPN virus challenge test, while the cardiac immune modulatory effects were characterized by qPCR and microarray gene expression analyses. In addition, swimming performance and growth parameters were investigated. Survival after the IPN challenge was higher for IT (74%) fish than for either CT (64%) or C (61%) fish. While both CT and IT groups showed lower cardiac transcription levels of TNF-α, IL-1β and IL-6 prior to the IPN challenge test, IT fish showed the strongest regulation of genes involved in immune responses and other processes known to affect disease resistance. Both CT and IT regimes resulted in better growth compared with control fish, with CT fish developing a better swimming efficiency during training. Overall, interval aerobic training improved growth and increased robustness of Atlantic salmon, manifested by better disease resistance, which we found was associated with a modulation of relevant gene classes on the cardiac transcriptome.

Oral vitamin E supplementation on oxidative stress, vitamin and antioxidant status in intensely exercised horses

REASONS FOR PERFORMING STUDY

Vitamin E is the most commonly supplemented antioxidant in horses; however, previous research is not conclusive as to the recommended level for exercising horses.

OBJECTIVE

To evaluate the effects of 3 levels of vitamin E supplementation on oxidative stress and vitamin/antioxidant status in intensely exercised horses to determine the optimal level of vitamin E supplementation.

METHODS

Twelve unfit Standardbreds were divided into 3 groups, supplemented orally with 0 (CON), 5000 (MOD), or 10,000 (HI) iu/day of DL-alpha-tocopheryl acetate. The 3 x 3 Latin square design consisted of three 4 week supplementation periods with 4 week wash out periods between. After each period, horses underwent a treadmill interval exercise test. Blood samples were collected and heart rate (HR) measured before, during and after exercise. Data were analysed using ANOVA with repeated measures in SAS.

RESULTS

The CON group had lower HR throughout the test compared to the MOD and HI groups (P<0.05). There was an increase in plasma retinol (RET), beta-carotene (BC), red blood cell total glutathione and glutathione peroxidase with exercise (P<0.05), but all groups returned to baseline after 24 h. Plasma alpha-tocopherol (TOC) increased from baseline with exercise (P<0.0001) in all groups; treatment differences were observed at 24 h (P<0.05). The HI and CON groups had lower BC compared to the MOD group (P = 0.05).

CONCLUSIONS

Horses supplemented with vitamin E, at nearly 10-times the 1989 NRC recommended level, did not experience lower oxidative stress compared to control horses. Additionally, lower plasma BC levels observed in the HI group, which may indicate that vitamin E has an inhibitory effect on BC metabolism.

POTENTIAL RELEVANCE

Supplementation above control levels is not more beneficial to oxidative stress and antioxidant status in intensely exercising horses; indeed, levels 10 times in excess may be detrimental to BC and should be avoided.

Investigation of blood oxidant/antioxidant markers in healthy competition horses of different breeds

REASONS FOR PERFORMING STUDY

There is increasing evidence that the equine athlete is exposed to exercise-induced changes of its oxidant/antioxidant balance and antioxidant supplementation is frequently recommended. However, it is unknown whether there is a specific need for antioxidants according to performance, breed, gender or age.

OBJECTIVES

To assess whether breed-, gender- and age-related differences of blood oxidant/antioxidant markers occur in competition horses.

METHODS

Healthy horses (n = 493) underwent oxidant/ antioxidant blood marker determination. Vitamin E, lipophilic antioxidant capacity (ACL), ascorbic acid (AA), glutathione (GSH, GSSG), gluthione peroxidase (GPx), superoxide dismutase (SOD), selenium (Se), copper (Cu), zinc (Zn), lipid peroxides (Pool), oxidised proteins (Protox) were determined, as well as magnesium (Mg), creatine phosphokinase (CPK), lactate dehydrogenase (LDH), packed cell volume (PCV) and haemoglobin (Hb). A mixed linear model assessed the effect of breed, gender and age category. P<0.05 was considered significant.

RESULTS

Thoroughbreds showed the highest values of vitamin E, ACL, GPx, PCV and Hb, whilst standardbreds had the highest values of AA and LDH. Jumping horses had the highest Protox values. Females had significantly higher SOD values, whereas most of the other markers were higher in stallions and geldings. Horses age 2-6 years had higher AA, SOD and LDH values than horses age >6 years. Correlation analyses were positive and significant between vitamin E and GPx, VitE and ACL, Se and GPx, Cu and Pool and negative between Pool and vitamin E, Pool and ACL, Protox and GPx, Protox and vitamin E.

CONCLUSIONS

Blood oxidant/ antioxidant status of horses is influenced by breed, gender and age. The correlation analyses suggest synergistic relations between GPx, vitamin E and Se and an antagonistic relation between Protox-GPx, Protox-vitamin E, and Pool-vitamin E.

POTENTIAL RELEVANCE

The results of this investigation provide definition of the specific need for antioxidants and vitamins in competition horses.

alpha-Lipoic acid modulates thiol antioxidant defenses and attenuates exercise-induced oxidative stress in standardbred trotters

Several micronutrient supplementation strategies are used to cope with oxidative stress, although their benefits have recently been questioned. The aim of the present study was to examine the effects of DL-alpha-lipoic acid (LA) in response to acute exercise and during recovery in horses. Six standardbred trotters were tested on the treadmill before and after 5-week LA supplementation (25 mg/kg body weight/day). According to electron paramagnetic resonance measurements, strenuous aerobic exercise increased significantly free radical formation in the gluteus medius muscle, which was prevented by LA supplementation. The activities of thioredoxin reductase and glutathione reductase in muscle were significantly increased in LA-treated horses, but neither LA nor exercise affected muscle thioredoxin activity. LA increased the concentration of total glutathione in muscle at rest and during recovery. Treatment with LA blunted the exercise-induced increase in plasma oxygen radical absorbance capacity and decreased the post-exercise levels of lipid hydroperoxides in plasma and malondialdehyde in plasma and in muscle. These findings suggest that LA enhances thiol antioxidant defences and decreases exercise-induced oxidative stress in skeletal muscle.

Metabolic and hematological profiles in mature horses supplemented with different selenium sources and doses

This study was conducted to determine the effects of dietary Se source and dose on metabolic and hematological profiles, and their relationships with oxidative status in horses. Twenty-five mature horses were blocked by BW and randomly allocated to 1 of 5 dietary treatments: negative control (CTRL: 0.085 mg of Se/kg of DM), 3 different dietary concentrations of organic Se provided by Se yeast (SY02, SY03, and SY04 containing 0.2, 0.3, and 0.4 mg of total Se/kg of DM, respectively), and 1 positive control provided by sodium selenite (SS03 containing 0.3 mg of total Se/kg of DM). Horses were fed the same basal diet (6 kg of grass hay and 3 kg of concentrate per horse daily) and received their respective treatments for a continuous period of 112 d. Jugular venous blood samples were collected before the morning feed on d 0, 28, 56, 84, and 112. Whole blood was analyzed for hematological profile, and plasma was analyzed for metabolites of energy, protein, and mineral metabolism; enzymatic activities and metabolites related to liver and muscle damage; and markers of inflammatory and oxidative status. Plasma metabolites related to energy, protein, and mineral metabolism, acute phase proteins, and enzyme activities related to hepatocellular, hepatobiliary, and muscle damage were not affected by Se source or dose. There were no differences among treatments in either reactive oxygen metabolites or thiol group concentrations in plasma. However, a linear decrease (P < 0. 01) in plasma total antioxidants was observed with increasing Se yeast supplementation. Furthermore, total antioxidant concentrations were less in SY03 than SS03 horses (P < 0.05), and were less in SY03 and SY04 than CTRL horses (P < 0.05). These results could be interpreted as an improvement in the preventive antioxidant systems of horses fed Se yeast. Total white blood cell count was not affected by treatment. There was a tendency for horses receiving greater concentrations of Se yeast to have greater lymphocyte counts (P = 0.09), with greater lymphocyte counts in blood of SY03 vs. SS03 horses (P < 0.05). Despite the lack of effect of Se source and dose on markers of inflammatory and liver status, the hematological profile seems to indicate an immunomodulatory action, as shown by mild changes in the white blood cell populations in response to Se yeast inclusion.

Whole blood selenium concentrations in endurance horses

Exercise causes an increase in the production of reactive oxygen species, which can result in oxidant/antioxidant disequilibrium. Deficiency of antioxidants can further alter this balance in favor of pro-oxidation. Selenium (Se) is one of many antioxidant catalysts, as a component of the glutathione peroxidase enzymes. Soils and forages vary widely in Se concentration and a deficient diet can lead to sub-clinical or clinical deficiency in horses. Endurance horses are prone to oxidative stress during long periods of aerobic exercise and their performance could be affected by Se status. This study investigated the blood Se concentration in a group of endurance horses (n=56) residing and competing in California, a state containing several regions that tend to produce Se-deficient forages. The rate of Se deficiency in this group of horses was low, with only one horse being slightly below the reference range. Higher blood Se concentrations were not associated with improved performance in terms of ride time. There was no significant difference in Se concentration between horses that completed the ride and those that were disqualified, although blood Se concentrations were significantly higher in horses that received oral Se supplementation. An increase in blood Se concentration was observed following exercise and this warrants further study.

Prophylaxis of heterotopic ossification - an updated review

Heterotopic ossification (HO) is defined as the process by which trabecular bone forms outside of the skeletal structure, occupying space in soft tissue where it does not normally exist. The current popular prophylactic treatment modalities include non-steroidal anti-inflammatory drugs (NSAIDs) and radiation therapy, although the literature remains inconclusive as to which is superior. Additionally, both treatments can lead to adverse effects to the patient. Recently there have been several studies attempting to identify new aspects of the etiology of heterotopic bone formation and introduce new prophylactic modalities with increased efficacy and fewer side effects. For this review, we selectively retrieved articles from Medline published from 1958–2008 on the prophylaxis of HO with the aim of assisting readers in quickly grasping the current status of research and clinical aspects of HO prophylaxis.

Effects of vitamin E and selenium on serum trace and major elements in horses

The combined effects of vitamin E and selenium were studied in native Anatolian horses subject to strenuous exercise. The concentrations of copper, zinc, iron, calcium, potassium, and magnesium were determined in serum by atomic absorption spectrometry in two study groups (n = 25 each), one of which served as untreated controls. After exercising the horses by running 1,500 m in about 7 min, only the copper level and the copper/zinc ratio significantly increased (p < 0.05), but the concentrations of calcium, potassium, iron, and magnesium remained unchanged. In horses treated with vitamin E and selenium, the calcium and potassium levels decreased to levels lower than those of untreated controls before and after exercise. The iron levels were not changed by exercise or treatment alone but increased when the horses had been supplemented and exercised. The copper level and the copper/zinc ration increased as a result of exercise in both treated and untreated horses. These changes suggest that supplementation with vitamin E and selenium had an important effect on the serum concentrations of calcium, potassium, copper, iron, and the copper/zinc ratio.

Oxidative stress

Oxidative stress refers to the cellular injury and pathologic change that occurs when there is an imbalance favoring oxidants over antioxidants within a living organism. In human medicine, oxidative stress has been implicated in numerous disease processes, which has led to further research into the clinical benefits and efficacy of antioxidant therapy. The evaluation of oxidative stress in the horse has been limited primarily to ischemia-reperfusion injury of the gastrointestinal tract, recurrent airway obstruction, exercise, osteoarthritis, equine motor neuron disease, and pituitary pars intermedia dysfunction. Each of these is examined in this review in terms of the current evidence for oxidative stress as well as the evidence for current antioxidant therapy in equine medicine and the potential of future research and therapies. Oxidative stress research is currently an emerging field with relevance to the equine critical patient.