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Sixty-day oral antioxidant supplementation enhances sperm morphology and seminal plasma antioxidant capacity in stallions.
Abstract: While dietary supplementation with antioxidants has been identified as an effective strategy for mitigating oxidative stress (OS) damage in stallion sperm, specific protocols and the duration of its efficacy remain poorly defined. This study aimed to evaluate the effects of a 60-d dietary supplementation with a commercial antioxidant combination on semen quality and OS biomarkers in stallions. Stallions were divided into two groups: the control group (n = 5; CTRL) received 30 g/500 kg of placebo while the treated group (n = 5; OXY) received 30 g/500 kg of Oxyliver daily for 60 d. Semen was evaluated for volume, concentration, viability, morphology, membrane integrity, motility, and kinetic parameters every 15 d for the 60-d supplementation period and for an additional 60 d after treatment cessation (D0, D15, D30, D45, D60, DP15, DP30, DP45, DP60). Total antioxidant capacity (TAC), ferric reducing/antioxidant power (FRAP), and malondialdehyde (MDA) were measured at 30-d intervals. The change in sperm parameters over time differed significantly between groups, specifically for sperm membrane integrity (P = 0.004), total motility (P = 0.003), morphological abnormalities (P = 0.028), and OS parameters (TAC P = 0.031, FRAP P = 0.044, MDA P = 0.048). Compared to CTRL, the OXY group showed greater sperm membrane integrity (P = 0.004) and total motility (P = 0.039) at D60. Conversely, total morphological abnormalities were lower in OXY at D60 (P = 0.003), DP15 (P = 0.009), and DP30 (P = 0.018), mainly due to a reduction in tail defects at the same time points (P = 0.008, P = 0.014, P = 0.020, respectively). Moreover, TAC and FRAP were greater in the OXY group at D30 (P = 0.004 and P = 0.012, respectively) and D60 (P = 0.001 and P = 0.009, respectively), while MDA concentrations were lower in the OXY group at D60 (P < 0.001), DP30 (P = 0.033) and DP60 (P = 0.003). In conclusion, despite the small sample size, this longitudinal study provides preliminary evidence that a 60-d supplementation with this combined formula enhances seminal plasma antioxidant capacity during supplementation and reduces lipid peroxidation even after the end of supplementation. It also induces a transient improvement in sperm membrane functionality and total motility at specific time points, whereas sperm morphology showed a more robust improvement beyond the supplementation period. Oxidative stress is a key factor affecting sperm quality and fertility in stallions, as it can impair sperm function and increase cellular damage. Dietary antioxidant supplementation has been proposed as a strategy to counteract these effects, although its efficacy and duration of action are not fully established. This study evaluated the effects of a 60-d dietary supplementation with a commercial antioxidant formulation on semen quality and oxidative status in stallions. Supplemented stallions showed robust and long-lasting improvements in sperm morphology, specifically a reduction in total sperm abnormalities, driven by a reduction in tail defects, with positive effects persisting up to 60 d after treatment. Moreover, this supplementation increased sperm total motility at specific time points (at the end of supplementation and 30 d after), but not other motility or kinetic parameters, and temporarily improved sperm membrane functionality at 60 d of supplementation. In addition, antioxidant capacity in seminal plasma increased, while markers of lipid peroxidation decreased. Some of these effects persisted after the end of the supplementation period, suggesting a sustained benefit. Overall, these results indicate that dietary antioxidant supplementation can improve semen quality and modulate oxidative status in stallions.
© The Author(s) 2026. Published by Oxford University Press on behalf of the American Society of Animal Science.
Publication Date: 2026-08-25 PubMed ID: 42640568PubMed Central: PMC13570791DOI: 10.1093/jas/skag265Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
Summary
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Overview
- This study investigated the impact of a 60-day dietary antioxidant supplementation on semen quality and oxidative stress markers in stallions.
- The research found that supplementing antioxidants improved sperm morphology, motility, and seminal antioxidant capacity, with some benefits lasting beyond the supplementation period.
Background and Objective
- Oxidative stress (OS) negatively affects sperm quality and fertility in stallions by damaging sperm cells and reducing their functionality.
- Antioxidant dietary supplements are proposed to mitigate OS damage, but optimal protocols and duration of efficacy are unclear.
- This study aimed to assess the effects of a 60-day supplementation with a commercial antioxidant blend (Oxyliver) on semen quality and oxidative stress biomarkers in stallions.
Study Design and Methods
- Ten stallions were divided into two groups:
- Control (CTRL; n=5) received a placebo dosage daily.
- Treated (OXY; n=5) received 30 g/500 kg of Oxyliver daily for 60 days.
- Semen characteristics evaluated every 15 days during supplementation and for 60 days after cessation (total up to 120 days):
- Volume
- Concentration
- Viability
- Morphology
- Membrane integrity
- Motility and kinetic parameters
- Oxidative stress biomarkers measured every 30 days:
- Total antioxidant capacity (TAC)
- Ferric reducing/antioxidant power (FRAP)
- Malondialdehyde (MDA), a lipid peroxidation marker
- Statistical analysis compared changes over time between CTRL and OXY groups.
Key Findings on Semen Quality
- Sperm membrane integrity and total motility were significantly higher in the OXY group at day 60 of supplementation indicating improved sperm function.
- Overall sperm morphological abnormalities were lower in the OXY group at day 60 and persisted at 15 and 30 days post-supplementation, primarily due to fewer tail defects.
- Other motility and kinetic parameters did not show significant changes.
Effects on Oxidative Stress Markers
- The OXY group exhibited significantly higher seminal plasma antioxidant capacity (TAC and FRAP) at days 30 and 60.
- MDA levels, which indicate lipid peroxidation damage, were substantially lower in the OXY group at day 60 and persisted to be lower at 30 and 60 days after supplementation ended.
- These changes suggest enhanced antioxidant defenses and reduced oxidative damage during and after supplementation.
Interpretation and Implications
- The 60-day oral antioxidant supplementation improved sperm morphology notably, with a durable effect lasting beyond the supplementation period.
- Improvements in sperm membrane integrity and total motility were more transient, peaking at the end of supplementation or shortly after.
- The enhancement in seminal plasma antioxidant capacity and concurrent reduction in lipid peroxidation markers indicate that supplementation effectively modulated oxidative stress in stallions.
- Despite the small sample size, results provide preliminary evidence that targeted antioxidant supplementation may be a beneficial strategy to improve stallion semen quality and reduce OS-associated damage.
- Further research with larger cohorts is necessary to confirm findings and optimize supplementation protocols for reproduction management in stallions.
Cite This Article
APA
Del Prete C, Longobardi C, Longobardi V, Piscopo F, Ciarcia R, Cocchia N, Pasolini MP, Cutrignelli MI, Vastolo A.
(2026).
Sixty-day oral antioxidant supplementation enhances sperm morphology and seminal plasma antioxidant capacity in stallions.
J Anim Sci, 104, skag265.
https://doi.org/10.1093/jas/skag265 Publication
Researcher Affiliations
- Department of Human Science, Link Campus University, Rome 00165, Italy.
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, Naples 80137, Italy.
- Department of Experimental Medicine, University of Rome-Tor Vergata, Rome 00133, Italy.
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, Naples 80137, Italy.
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, Naples 80137, Italy.
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, Naples 80137, Italy.
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, Naples 80137, Italy.
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, Naples 80137, Italy.
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, Naples 80137, Italy.
MeSH Terms
- Animals
- Male
- Horses / physiology
- Antioxidants / pharmacology
- Antioxidants / administration & dosage
- Antioxidants / metabolism
- Spermatozoa / drug effects
- Spermatozoa / physiology
- Dietary Supplements
- Semen Analysis / veterinary
- Semen / drug effects
- Oxidative Stress / drug effects
- Diet / veterinary
- Sperm Motility / drug effects
- Administration, Oral
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