Effect of a dietary antioxidant supplementation on semen quality in pony stallions

Effect of nutraceutical supplementation on semen quality in stallions

BACKGROUND

The use of reproductive biotechnologies in equine practice has shown that some stallions are subfertile, so ways to improve fertility have been sought.

OBJECTIVE

This study aimed to evaluate the effect of nutraceutical supplementation on improving semen quality in Quarter Horse stallions.

METHODS

Semen from six Quarter Horse stallions was assessed for 4 months every 20 days using the computer-assisted semen analysis system. They were evaluated for 60 days before supplementation; then, the same stallions were re-evaluated for 60 days with nutraceutical supplementation (30 g/day).

RESULTS

Volume showed no significant difference (p > 0.05) with nutraceuticals. Sperm concentration (10x6 ) was significantly higher with supplementation (339.4 ± 17.5 sperm/mL) than without supplementation (224.6 ± 19.9). Sperm abnormalities (%) were significantly (p < 0.05) lower with supplementation (14.3 ± 0.6) than without supplementation (19.1 ± 0.4). Sperm kinematic parameters, total motility (TM), progressive motility (PM), rectilinear velocity (VSL), the velocity of the trajectory (VAP) and curvilinear velocity (VCL), were significantly better with supplementation (p < 0.05).

CONCLUSIONS

Based on the results, it is concluded that nutraceutical supplementation improved semen parameters in Quarter Horse stallions.

Effects of Dietary Zn/Se and α-Tocopherol Supplementation on Metabolic Milieu, Haemogram and Semen Traits of Breeding Stallions

Trace element status and metabolic milieu are sometimes overlooked in common veterinary clinical practice across animal species. The evaluation of requirements of trace elements, in fact, may be useful to prevent the perturbation of tissue-specific metabolic impair. In particular, essential trace elements in the diet play key roles within sub-cellular metabolic patterns with macro effects at the systemic level, like blood cell stability and semen quality. This effect was studied in breeding stallions, in which semen quality and haemogram are important for reproduction. A case-control feeding trial involved 40 stallions (age: 8-21 years; body weight, BW: 510-531 kg) of one stud centre, allotted to two experimental groups (n = 20 control, CON vs. n = 20 supplemented, SUPPL100), following a matched-pairs approach based on age. Supplemented stallions (SUPPL100) received a mixed mineral and vitamin supplement of Zn/Se and α-tocopherol (α-TOH) (100 g/day stallion) to compound feed, fed as control diet to horses of the control group (CON). Horses resulted deficient in circulating α-TOH and Zn at the start, though clinically healthy. After supplementation, different plasmatic levels of α-TOH, Zn and Se were found between groups. Circulating basophils (BASO) and mean cell haemoglobin concentration (MCHC) were affected by the dietary treatment (p < 0.05). Plasmatic Se affected monocyte count, haematocrit, mean cell volume and mean cell haemoglobin concentration. Semen traits were not affected by the dietary treatment per se, except for mobile/progressive sperm cells (%) of stallions aged > 13 years marginal circulating levels of α-TOH (p = 0.04). Ameliorating the micromineral status showed to improve the haemogram of stallions in view of circulating levels of Cu. Semen quality appeared to be strongly dependent on animal effects.

Use of nutraceuticals in the stallion: Effects on semen quality and preservation

Nutritional supplements are widely used in the equine industry with the aim of improving horse health, sports or reproductive performances. Over the years, a number of studies have focused on investigating the effects of several dietary compounds on the quality and preservation of stallion semen. This paper reviews the literature available on the use of nutritional supplementation for the improvement of reproductive performance and semen quality in equine species, critically appraising the benefits and negative effects of several compounds found in complementary feeds such as PUFAs from different sources, vitamins and antioxidants, carnitine and botanical extracts. Different nutraceuticals have been highlighted to improve stallion fertility by providing optimal levels of antioxidants, with the most promising results obtained by the combination of PUFAs and antioxidants that resulted to be essential for the maintenance of normal reproductive functions and the reduction of cryodamage in cooled and frozen equine semen.

Effects of Feeding Coenzyme Q10-Ubiquinol on Plasma Coenzyme Q10 Concentrations and Semen Quality in Stallions

Although coenzyme Q10 (CoQ10) serves as an antioxidant and energy source for spermatozoa when added to stallion semen before cooling or freezing, the effects of feeding CoQ10 on semen quality have not been studied. We assessed the effects of daily oral ingestion of CoQ10-ubiquinol by stallions on their plasma CoQ10 concentrations and semen quality. Seven mature Andalusian stallions ate 1g ubiquinol/day for 4 weeks followed by a 4-week washout period. Four horses initially completed an additional 4-week control period without ubiquinol. Blood was sampled weekly for determination of plasma CoQ10 concentrations. Ejaculates were collected every two weeks and assessed for total motility (TM), progressive motility (PM), and viability (V) after cooling for 24hours (T₁), immediate cryopreservation (T₂), and cryopreservation after 24hours cooling (T₃). Ingesting ubiquinol resulted in an increase in plasma CoQ10 concentration (P < .001). Two weeks of CoQ10-ubiquinol resulted in improved V with all treatments (T₁: P = .007; T₂: P = .05; T₃: P = .01) and PM with T₃ (P = .04). In five stallions, TM and PM were also improved for T₁ (P = .01 and P = .02, respectively) and TM increased with T₂ (P = .03). Overall, semen quality parameters increased within the first 2 weeks of supplementation, plateaued at the end of the 4-week supplementation period and persisted after discontinuing ubiquinol until the end of the sampling period (8 weeks). Feeding 1 g CoQ10-ubiquinol for 4 weeks to breeding stallions improved semen quality after cooling and freezing in 5 of 7 stallions. This could be important for improving reproductive efficiency in stallions.

Herbal yeast product, Equi-Strath®, alters the antioxidant status of stallion semen

Effects of a plasmolysed yeast product enriched with herbs, malt, honey and orange syrup on semen characteristics and oxidative status in stallions were evaluated. Twenty stallions (mean age ± standard deviation = 9.5 ± 4.5 years) were randomly divided into a treatment group (n = 10) receiving 0.06 mL/kg bodyweight of plasmolysed herbal yeast, and a control group (n = 10) receiving the same amount of placebo daily in the feed for 10 weeks. Ejaculates were collected weekly from all stallions starting at Week 0. Volume, sperm concentration, motility, and velocity were evaluated immediately, 24 and 48 h after cooled storage at 5 °C. At the two storage time points, membrane lipid peroxidation was determined using the BODIPY-C₁₁. Additionally, blood samples were collected at Weeks 0, 1, 5 and 9, and analysed for antioxidant status, consisting of superoxide dismutase, cholesterol, thiobarbituric acid reactive substances, and non-esterified fatty acids. Due to the nature of the data, the Mann-Whitney U test was applied as preliminary analysis. The BODIPY-C₁₁ in the semen was less at 24 h and greater at 48 h after collections in Week 1 to 3 (P < 0.01) and Week 1 to 10 (P <  0.05) compared with Week 0 in the treatment compared to control group. There were no significant differences between groups for all values for other seminal and blood variables evaluated. In conclusion, feed supplementation with plasmolysed herbal yeast temporarily improved the antioxidant status of stallion semen, which might be of benefit for preservation of cooled semen.

Effect of dietary grape marc on fresh and refrigerated boar semen

In several studies there has been evaluation of the dietary addition of antioxidants to improve the quality of fresh and stored semen in domestic animals. Grape marc (GM), as the residue of vinification, contains large amounts of polyphenols with antioxidant, anti-inflammatory, antimicrobial, and antiaging effects. In this study, two regimens of dietary GM supplementation (2% and 4%) were tested regarding effects on the characteristics and lipid peroxidation of fresh and stored semen. The dietary supplementation of GM improved sperm characteristics in fresh semen, especially at 4% of GM. There were greater values for all kinetic variables and membrane integrity, and lesser values for sperm abnormalities and lipid peroxidation with 2% and 4% GM supplementation. Lipid peroxidation of the pellet was less with both 2% and 4% GM supplementation. During sperm storage, the dietary supplementation of GM improved the quality of sperm, with greater values for kinetic variables and membrane integrity at day 15 of storage. In the present study, supplementation of GM in boar diets improved fresh semen characteristics and reduced the lipid peroxidation of ejaculated spermatozoa, possibly due to the effect of polyphenols present in the GM. Consequently, this likely resulted in improved sperm quality during storage.

Influences of a diet supplemented with linseed oil and antioxidants on quality of equine semen after cooling and cryopreservation during winter

Seasonal changes in the reproductive physiology of stallions contribute to a decrease in the quality of frozen-thawed semen during late winter. Changes in the lipid composition of the sperm plasma membrane may contribute to this phenomenon. In the present study, we have, therefore, investigated the effects of adding linseed oil (LO) in combination with antioxidants to the diet of breeding stallions on the motility and membrane integrity of cooled-stored and cryopreserved semen. Starting in November, the diet of LO stallions (n = 6) but not control (C) stallions (n = 5) was supplemented with LO (100 mL once daily) plus an antioxidant (Myostem Protect; Audevard, Clichy, France) for a total of 84 days. Before (November) and at the end of this period (February), ejaculates were processed for cryopreservation (n = 3 ejaculates per stallion) and cooled shipping at 5 °C. Frozen-thawed and cooled-shipped semen was sent to the laboratory for computer-assisted semen analysis of total motility, progressive motility, and velocity parameters (average path velocity [VAP], curved line velocity [VCL], and straight-line velocity [VSL]) and evaluation of membrane integrity. The quality of frozen-thawed semen decreased (P < 0.05) from November (e.g., total motility LO 69 ± 3% and C 67 ± 3%) to February (total motility: LO 55 ± 4% and C 59 ± 3%) independent of treatment (P > 0.05). A decrease in the velocity parameters VAP, VCL, and VSL was more pronounced in LO stallions than in C stallions (e.g., VSL: November LO 67 ± 1 μm/s, C 64 ± 2 μm/s; February LO 59 ± 2 μm/s, C 63 ± 2 μm/s; interaction month by treatment, P < 0.05). In cooled-stored semen, total motility, progressive motility, and membrane integrity were lower in February than in November (P < 0.001 for all parameters). Supplementation of the diet with LO and antioxidants attenuated this decrease (e.g., Day 1 of cooled storage = 24 hours after semen collection: total motility in November LO 88 ± 1% and C 87 ± 3%; in February LO 83 ± 2% and C 73 ± 11%; interaction month by treatment: P < 0.05). Velocity parameters VAP, VCL, and VSL were significantly lower in February than in November (P < 0.001), but this decrease was not affected by treatment. In summary, dietary supplementation of stallions with LO plus antioxidants attenuated a decline in motility and membrane integrity of cooled-stored stallion semen during winter. This may improve the fertility of cooled-shipped semen. In contrast, the treatment did not counteract the decrease in quality of frozen-thawed semen that occurs in late winter.

Reactive oxygen species in stallion semen can be affected by season and colloid centrifugation

There are anecdotal reports that equine fertility may decline towards the end of the breeding season. Previous studies have examined differences in sperm quality between the breeding season and non-breeding season but few studies have investigated the proportions of superoxide or peroxide containing spermatozoa at different times during the breeding season. The purpose of this study was to measure the content of these reactive oxygen species (ROS) at the beginning and end of the Swedish breeding season, using flow cytometric analysis of the fluorescence produced after staining with hydroethidium and dichlorodihydrofluorescein diacetate. In addition, the effects of a new method of selecting good quality spermatozoa by colloid centrifugation, known as Single Layer Centrifugation (SLC), on ROS-content were investigated. Superoxide production by stallion spermatozoa was found to be higher at the start than at the end of the breeding season in Sweden (22±16% versus 9±6%, P<0.05), whereas sperm motility was lower (total motility 80±9% versus 90±6%, P<0.01; progressive motility 55±12% versus 60±8%, P<0.05, at the beginning and end of the breeding season respectively). The mean values of the other parameters of sperm quality measured did not differ with time within the breeding season although differences did occur for individual stallions. SLC was found to select motile spermatozoa that contained less superoxide (16±14% versus 23±18%, P<0.01) and less peroxide (0.3±0.8 versus 1±2%, P<0.01) than uncentrifuged controls, although they were capable of producing ROS when stimulated with menadione. This reduced peroxide production may contribute to the enhanced sperm survival (retention of motility) seen in the SLC samples during storage.