Translational animal science2021; 5(2); txab045; doi: 10.1093/tas/txab045

The effect of time of feeding on plasma amino acids during exercise and recovery in horses.

Graham-Thiers, PM
·
Bowen, LK

Abstract: Feeding management in horses suggests feeding horses in advance of exercise, particularly the grain portion of the diet. Plasma amino acids () peak at 3 to 6 h postfeeding depending on the AA. The timeframe between feeding and exercise may affect the availability of AA during and after exercise. The purpose of this study was to observe the differences in plasma AA in horses fed prior to exercise or after exercise. Eight light type horses were fed a diet with adequate protein and AA for horses in light to moderate exercise. After an adjustment period, horses completed a standardized exercise test (). Relative to the SET, horses were fed either 2 h prior ( horses) to the SET, 1 h after completing the SET ( horses), or horses remained fasted throughout the sampling period ( horses). Plasma was drawn prior to exercise, at the peak of exercise as well as at 1, 2, 4, and 7 h postexercise. Plasma was analyzed for AA, glucose, lactate, creatinine, creatine kinase, ammonia, urea-N, and 3-methylhistdine. After completion of the SET and sampling period, horses entered a 1-wk recovery period, which was followed by another SET. The protocol repeated until horses rotated through all feeding protocols in the study (three SETs). The majority of the plasma AA were elevated in PRE horses compared with POST horses prior to the SET until 2 h postexercise where POST horses' plasma AA concentrations became elevated and remained elevated until the end of the sampling period. In that same time frame, plasma AA for the PRE group decreased out to the end of the sampling period. The elevation of plasma AA in POST horses would be expected as they were fed at 1 h postexercise, whereas PRE horses were reaching a 4 h postfeeding time frame at this point. This elevation was not observed for plasma concentrations of isoleucine, leucine, methionine, and histidine. Concentrations of these AA initially were greater for POST horses in the postexercise period; however, they declined more rapidly than the other AA. The rapid decrease of some of the plasma AA concentrations may suggest uptake by muscle for recovery. This in conjunction with a decrease in plasma creatine kinase concentrations for POST horses suggests that feeding postexercise may facilitate better muscle protein balance (synthesis vs. breakdown) in the recovery period following exercise.

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Publication Date: 2021-03-23 PubMed ID: 34179699PubMed Central: PMC8221455DOI: 10.1093/tas/txab045Google Scholar: Lookup

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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.

The research is about the effects of feeding times on the plasma amino acid levels during and after exercise in horses. It investigates whether feeding horses before or after exercising impacts the availability of amino acids and the recovery process. The study concludes that feeding after exercise could facilitate a better muscle protein balance through increased amino acid uptake and decreased creatine kinase concentration.

Objective of the Study

The study’s primary aim is to determine how the timing of feeding horses affects the plasma amino acid (AA) availability during and after exercise. It compares the plasma AA levels of the horses fed before exercise, after exercise, and those that fasted throughout the study period.

Study Design and Methodology

The study involved the use of eight light-type horses on a diet rich in proteins and amino acids suitable for horses engaged in light to moderate level exercises.
After a period of adjustment, the horses participated in a Standardized Exercise Test (SET).
The horses were fed according to three different feeding schedules relative to the exercise. The groupings were; feeding 2 hours before the SET, feeding 1 hour after the SET, and horses that fasted throughout the experiment.
Plasma was drawn from the horses and analyzed at different intervals; before exercise, at the peak of exercise, and at intervals of 1, 2, 4, and 7 hours post-exercise.
Plasma was tested for AA, glucose, lactate, creatinine, creatine kinase, ammonia, urea-N and 3-methylhistdine.

Key Findings

The majority of the plasma AA were found to be higher in the horses fed before (PRE) exercise, compared with those fed after (POST) exercise from pre-exercise time until 2 hours post-exercise.
However, starting from 2 hours post-exercise, the levels of plasma AA in POST horses (those fed after exercise) became and remained higher until the end of the sampling period. At the same time, the PRE group’s plasma AA levels steadily decreased.
The elevated plasma AA for the POST group was as expected. A decrease in plasma creatine kinase in the POST group also suggested that feeding after exercise could facilitate better muscle protein balance in the recovery period after exercise.
The decrease in plasma Isoleucine, Leucine, Methionine, and Histidine levels in POST horses after the initial surge suggested the uptake of these amino acids by the muscles for recovery.

Implications and Conclusion

The research showed that the timing of feeding relative to exercise impacts the plasma amino acid availability in the horses.
This study suggests that feeding horses post-exercise could promote better muscle recovery than when horses are fed pre-exercise. The changes in plasma AA and creatine kinase concentrations observed support this conclusion.

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APA

Graham-Thiers PM, Bowen LK. (2021). The effect of time of feeding on plasma amino acids during exercise and recovery in horses. Transl Anim Sci, 5(2), txab045. https://doi.org/10.1093/tas/txab045

Publication

Translational animal science

ISSN: 2573-2102

NlmUniqueID: 101738705

Country: England

Language: English

Volume: 5

Issue: 2

Pages: txab045

PII: txab045

Researcher Affiliations

Graham-Thiers, Patty M

Equine Studies Department, Emory & Henry College, Emory, VA 24327, USA.

Bowen, LaAnn K

Equine Studies Department, Emory & Henry College, Emory, VA 24327, USA.

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