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Journal of animal science2022; 100(4); skac086; doi: 10.1093/jas/skac086

Oxidative stress biomarkers and free amino acid concentrations in the blood plasma of moderately exercised horses indicate adaptive response to prolonged exercise training.

Abstract: Oxidative stress caused by routine physical stressors may negatively impact the performance of equine athletes; thus, the present study identifies oxidative biomarkers in the blood plasma of exercising horses. Stock-type horses were subject to a standardized moderate-intensity exercise protocol 3 times per week for 8 wk. Exercise protocol followed NRC guidelines consisting of 30% walk, 55% trot, and 15% canter, with a target heart rate (HR) of 90 BPM. Blood plasma was collected in wk 1, 2, 7, and 8 immediately before and 0, 30, 60, and 90 min after exercise and analyzed for total antioxidant capacity (TAC), thiobarbituric acid reactive substance (TBARS), glutathione peroxidase activity (GPx), and superoxide dismutase activity (SOD). Data were analyzed as repeated measures with wk, d, time, and their interactions as fixed effects. The TAC on day 2 (0.40 mM Trolox) was 7.5% greater than on day 3 (P = 0.013). There were wk × d × time interactions for SOD, TBARS, and GPx (P < 0.001). The TBARS remained at pre-exercise baseline (d-1 wk-1; 2.7 µM malondialdehyde) for most collection times within weeks 1, 7, and 8 (P ≥ 0.058); however, TBARS increased by 0.24 to 0.41 µM on day 2 of week 2 post-exercise (P < 0.001) and remained similarly elevated on day 3 pre- and immediately post-exercise (P < 0.001). The GPx similarly remained at baseline (172.6 µM/min; P ≥ 0.621) but increased by 48.18 to 83.4 µM/min at most collection times on days 1 and 2 of week 2 (P ≤ 0.023). The SOD remained at baseline (167.2 U/ mL; P ≥ 0.055) until increasing by 11.28 to 15.61 U/mL at 30 min post-exercise on day 1, week 1 and at most collection times on day 3, week 8 (P ≤ 0.043). Amino acids with antioxidant properties such as Met, Tyr, and Trp drastically decreased from weeks 2 to 8 (P < 0.001). Met and Tyr also decreased from -60 to 90 min (P < 0.047), whereas there was no time effect on Trp concentration (P = 0.841). The current study indicates the time-dependent nature of oxidative stress concerning persistent stressors such as exercise. Performance horses are subjected to numerous stressors. These stressors may subsequently impact their overall performance. The present study measured oxidative stress biomarkers in the blood of exercising horses. Horses were moderately exercised over an 8-wk period and blood plasma was collected to measure total antioxidant capacity (TAC), thiobarbituric acid reactive substance (TBARS), glutathione peroxidase activity (GPx), and superoxide dismutase activity (SOD). Amino acid concentration was also evaluated. The TAC was greater on day 2 vs. day 3. The TBARS remained at pre-exercise (baseline) at most times except for increasing on day 2 of week 2 post-exercise. The GPx also remained at baseline for most times but increased on days 1 and 2 of week 2. The SOD remained at baseline until increasing at 30 min post-exercise on day 1, week 1 and at most collection times on day 3, week 8. Amino acids with antioxidant properties drastically decreased from weeks 2 to 8. Horses are exposed to a variety of physical stressors on a regular basis that may produce similar effects in the equine stress response. Understanding the response in the equine athlete when exposed to new stressors is crucial in determining how to prevent oxidative damage in future athletes.
Publication Date: 2022-03-18 PubMed ID: 35298640PubMed Central: PMC9030216DOI: 10.1093/jas/skac086Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research explores how stress markers and amino acids found in horse’s blood plasma adjust in response to moderate, prolonged exercise. The study finds out that performance horses demonstrate a time-dependent adjustment to exercise stress, which is reflected in specific oxidative stress biomarkers and a decrease in certain amino acids.

Study Setup and Methods

  • The research focused on stock-type horses which underwent a standard moderate-intensity exercise protocol three times a week over an 8-week period. The designed exercise pattern followed Nutrition Requirements of Horses guidelines which contained walk (30%), trot (55%), and canter (15%) at a target heart rate of 90 BPM.
  • Blood plasma was collected on specific days and times (immediately before and 0, 30, 60, 90 minutes after exercise). This was done in the first, second, seventh, and eighth week.
  • The blood plasma was then examined for several indicators. These were the total antioxidant capacity (TAC), thiobarbituric acid reactive substance (TBARS), glutathione peroxidase activity (GPx), and superoxide dismutase activity (SOD). Any interactions and fixed effects influenced by day, duration, and week were statistically analyzed.

Findings

  • The research found certain variations in the recorded measurements. For instance, the total antioxidant capacity (TAC) on the second day showed a 7.5% increase compared to the third day.
  • However, by observing the mark changes in the oxidative stress biomarkers over time, there were interactions for SOD, TBARS, and GPx.
  • Specifically, TBARS remained at baseline levels during most of the collection times within weeks 1, 7, and 8. A notable spike was observed on the second day in the second week of training (post-exercise) and remained elevated on the third day (pre- and immediately post-exercise). GPx activity exhibited a similar pattern.
  • In contrast, SOD remained at the baseline level until it increased around 30 minutes after exercise on Day 1 of Week 1 and at most collection times of Day 3 in Week 8.
  • Moreover, there was a significant drop in concentrations of amino acids that demonstrate antioxidant properties (Met, Tyr, and Trp) from week 2 to 8 of the exercise protocol.

Implications

  • The performance of horses is subject to various stressors that can impact their performance. One of the stressors highlighted in this study is exercise.
  • This study unveils the time-dependent nature of oxidative stress related to persistent stressors like exercise. The changes over time in the oxidative stress biomarkers and amino acids in blood plasma give an insight into how horses are adapting to their training regimen.
  • Better understanding of an athlete horse’s response to continual stressors is important for the design of effective training methods to prevent oxidative damage, optimize performance, and maintain optimal horse health.

Cite This Article

APA
Ott EC, Cavinder CA, Wang S, Smith T, Lemley CO, Dinh TTN. (2022). Oxidative stress biomarkers and free amino acid concentrations in the blood plasma of moderately exercised horses indicate adaptive response to prolonged exercise training. J Anim Sci, 100(4), skac086. https://doi.org/10.1093/jas/skac086

Publication

ISSN: 1525-3163
NlmUniqueID: 8003002
Country: United States
Language: English
Volume: 100
Issue: 4
PII: skac086

Researcher Affiliations

Ott, Elizabeth C
  • Department of Animal and Dairy Sciences, Mississippi State University, Mississippi State, MS 39762, USA.
Cavinder, Clay A
  • Department of Animal and Dairy Sciences, Mississippi State University, Mississippi State, MS 39762, USA.
Wang, Shangshang
  • Department of Animal and Dairy Sciences, Mississippi State University, Mississippi State, MS 39762, USA.
Smith, Trent
  • Department of Animal and Dairy Sciences, Mississippi State University, Mississippi State, MS 39762, USA.
Lemley, Caleb O
  • Department of Animal and Dairy Sciences, Mississippi State University, Mississippi State, MS 39762, USA.
Dinh, Thu T N
  • Department of Animal and Dairy Sciences, Mississippi State University, Mississippi State, MS 39762, USA.

MeSH Terms

  • Amino Acids / metabolism
  • Animals
  • Antioxidants / metabolism
  • Biomarkers / metabolism
  • Glutathione Peroxidase / metabolism
  • Horses
  • Oxidative Stress / physiology
  • Physical Conditioning, Animal / physiology
  • Plasma / metabolism
  • Superoxide Dismutase / metabolism
  • Thiobarbituric Acid Reactive Substances

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