Influência do treinamento aeróbio sobre o cortisol e glicose plasmáticos em equinos

Training Effects on the Stress Predictors for Young Lusitano Horses Used in Dressage

The purpose of this study was to investigate stressful responses during a 6-week training protocol in young Lusitano horses used for dressage. The hypothesis was that the proposed training protocol would improve fitness and ensure the welfare of the animals by reducing stress predictors. Nine 4-year-old horses were evaluated before (M1) and six weeks after (M2) beginning a training protocol. The training program was performed six times per week and included 40−80 min of individually intensity-adjusted preparatory exercises for dressage. For both moments, the horses were examined before (T0) and after (T1) dressage simulation tests (DST), and at 30 (T2) and 240 min (T3) during the recovery period. Blood samples were taken to determine the horses’ cortisol levels, total WBC, and neutrophil and lymphocyte counts. All variables were analyzed by one-way ANOVA and Tukey tests, with p ≤ 0.05. After training, there was a significant reduction in cortisol (p = 0.0133), HR (p = 0.0283), total WBC (p < 0.0001), and neutrophil (p < 0.0001) and lymphocyte (p = 0.0341) counts. Other findings included an increase in HRV parameters related to a cardiac vagal modulation. In conclusion, the chosen training protocol led to better fitness as the horses worked more intensively with lower cardiovascular requirements, and they showed blunted cortisol responses at M2. Such data can be used to evaluate performance, but also to predict the welfare of athletic horses.

Identification and Functional Annotation of Genes Related to Horses' Performance: From GWAS to Post-GWAS

Simple Summary

It is assumed that the athletic performance of horses is influenced by a large number of genes; however, to date, not many genomic studies have been performed to identify candidate genes. In this study we performed a systematic review of genome-wide association studies followed by functional analyses aiming to identify the most candidate genes for horse performance. We were successful in identifying 669 candidate genes, from which we built biological process networks. Regulatory elements (transcription factors, TFs) of these genes were identified and used to build a gene–TF network. Genes and TFs presented in this study are suggested to play a role in the studied traits through biological processes related with exercise performance, for example, positive regulation of glucose metabolism, regulation of vascular endothelial growth factor production, skeletal system development, cellular response to fatty acids and cellular response to lipids. In general, this study may provide insights into the genetic architecture underlying horse performance in different breeds around the world.

Abstract

Integration of genomic data with gene network analysis can be a relevant strategy for unraveling genetic mechanisms. It can be used to explore shared biological processes between genes, as well as highlighting transcription factors (TFs) related to phenotypes of interest. Unlike other species, gene–TF network analyses have not yet been well applied to horse traits. We aimed to (1) identify candidate genes associated with horse performance via systematic review, and (2) build biological processes and gene–TF networks from the identified genes aiming to highlight the most candidate genes for horse performance. Our systematic review considered peer-reviewed articles using 20 combinations of keywords. Nine articles were selected and placed into groups for functional analysis via gene networks. A total of 669 candidate genes were identified. From that, gene networks of biological processes from each group were constructed, highlighting processes associated with horse performance (e.g., regulation of systemic arterial blood pressure by vasopressin and regulation of actin polymerization and depolymerization). Transcription factors associated with candidate genes were also identified. Based on their biological processes and evidence from the literature, we identified the main TFs related to horse performance traits, which allowed us to construct a gene–TF network highlighting TFs and the most candidate genes for horse performance.

Glutamine supplementation affects Th1 and Th2 cell populations in endurance horses

This study was set out to test the effect of glutamine supplementation on Th1 and Th2 cell populations in endurance horses. The sample was comprised 33 horses competing in four FEI races and successfully completing the final vet check. Horses competed in different distance categories, as follows: 80 km (13 horses, 6 supplemented and 3 controls), 120 km (14 horses; 9 supplemented and 5 controls) and 160 km (6 horses; 3 supplemented and 7 controls). Supplementation consisted of 60 mg/kg bodyweight of oral L-glutamine given for 30 days prior to and 15 days after the race. Blood samples were collected into vacuum tubes with and without EDTA at the following time points: short before race start time, prior to tack fitting (T0); right after and within 3 h of the final vet check (T1 and T2 respectively). Further blood samples were collected at the farm of origin 3, 7 and 14 days after the race (T3, T4 and T5 respectively). Glutamine supplementation affected T-lymphocyte population balance, as shown by increased CD4+/CD8+ ratio, and increased Th1 and Th2 cytokine production. Glutamine also modulated post-exercise cortisol increased in supplemented horses in this sample. These findings suggest glutamine supplementation attenuates exercise-induced immunosuppression.

Physical preparation and antioxidant supplementation for endurance racehorses

SUMMARY The objective of this review is to discuss aspects of the practice of endurance racing and alternatives to reduce oxidative stress in horses. Characterized by a high aerobic effort and requirement of the organic systems for maintenance of homeostasis, the endurance race is a form of sport for horses that demands great attention to the physical preparation of these animals and must be progressive, paying attention to the physiological parameters to evaluate the adaptation of the organism. To begin the preparation, the animals must be at least five years old and the duration can be on average of three years. Another factor that may be detrimental to the health and well-being of competing horses is the occurrence of oxidative stress, due to the accumulation of free radicals in the tissues, generating post-exercise muscle injuries. Antioxidant supplementation has been an alternative to this disorder. Several studies using compounds rich in antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), demonstrate positive effects on antioxidant status, markers of oxidative stress and muscle enzymes, which may represent an improvement in performance during the exercise and recovery of animals destined to the practice of equestrian sports. Therefore, a correct physical preparation becomes crucial and antioxidant supplementation may be used to maintain the health and well-being of horses destined to the equestrian endurance practice.

Equilíbrio ácido-base e hidroeletrolítico em equinos submetidos à simulação de enduro FEI *

RESUMO Enduro é uma modalidade equestre que demanda alta exigência dos sistemas orgânicos para que seja mantida a homeostasia do organismo. Objetivou-se avaliar o equilíbrio ácido-base e hidroeletrolítico durante uma prova de enduro realizada por equinos FEI*. Nove equinos foram submetidos a três meses de treinamento e, ao final, realizou-se prova similar às competições oficiais de enduro equestre, com trajeto de 80km, dividido em quatro etapas (anéis). Avaliações clínicas e coletas de amostras sanguíneas para análise da concentração de lactato e variáveis hemogasométricas foram realizadas no início da prova, imediatamente após a chegada de cada anel e, após 15 e 30 minutos, uma, quatro, seis e 12 horas do término da prova. Apenas cinco animais concluíram a prova e, para análise estatística, foram utilizados somente os dados destes animais. Houve predomínio do metabolismo aeróbio durante a prova e os animais mostraram bom índice de recuperação. Os eletrólitos cloreto, sódio, potássio e cálcio tiveram sua concentração diminuída, enquanto o bicarbonato aumentou no transcorrer do exercício. Os valores de pH aumentaram em decorrência do desenvolvimento de alcalose mista, caracterizada por alcalose metabólica hipoclorêmica e alcalose respiratória. O bom desempenho dos animais foi atribuído à suficiente adaptação metabólica induzida pelo treinamento.

Glicemia e concentrações séricas de insulina, triglicérides e cortisol em equinos da raça Mangalarga Marchador após exercício físico

O presente estudo teve por objetivo avaliar a influência do exercício físico de intensidade submáxima (provas de marcha) sobre as variáveis bioquímicas sanguíneas usadas na avaliação do metabolismo energético em equinos da raça Mangalarga Marchador criados no Estado do Espírito Santo. Para tal foram obtidas amostras de soro e plasma de 15 equinos, da raça Mangalarga Marchador, em quatro momentos assim definidos: antes (T0) e com 5 minutos (T1), 30 minutos (T2) e 2 horas (T3) após o término do exercício. A análise dos resultados demonstrou a não influência do exercício físico imposto sobre a glicose plasmática, com valores médios de 117,1±35,8mg/dL, 122,6±59,6mg/dL, 124,8± 48,6mg/dL e 112,9±49,1mg/dL, e sobre a insulina sérica, com valores de mediana de 6,50mUI/mL, 2,00mUI/mL, 5,85mUI/mL e 11,60mUI/mL, respectivamente, nos tempos T0, T1, T2 e T3. De forma oposta, foi possível observar uma influência significativa sobre triglicérides séricos, com valores médios de 25,4±14,9mg/dL, 42,3±17,8mg/dL, 31,4±17,7mg/dL e 25,1±15,1mg/dL, e sobre o cortisol sérico, com valores médios de 7,46±4,37mg/dL, 12,45±3,08mg/dL, 11,40±2,52mg/dL e 6,89±1,78mg/dL, respectivamente nos tempos T0, T1, T2 e T3. A interpretação destes resultados permitiu concluir que a marcha elevou as concentrações séricas de triglicérides e cortisol. Também foi possível destacar que, por tais valores encontrarem-se dentro de intervalos fisiológicos, os equinos usados estavam aptos ao nível de exercício físico imposto na ocasião.