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  Discussion on Research Summary: Antioxidants and Semen Quality
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Moderator:
DrO

Posted on Tuesday, Jul 12, 2011 - 8:45 pm:

In the last few decades we have seen several reports suggesting that horses were not receiving adequate nutritional support for antioxidants like vitamin E and selenium. Besides invitro experiments part of that evidence has been several neurological diseases that may be the result of too little antioxidant in the diet. As a result of these reports we have long recommended vitamin E supplementation at the rate of 500 to 1500 IU (depending on use) a day for a 1000 lb horse not on fresh green forage (see Vitamins for more). Here is some of the first proof that past NRC recommendations may not be adequate for optimal reproductive health.

It is interesting to look at the attention that is given to zinc in the nutritional study below. It has only been about 30 years that zinc has been attributed an important role as a antioxidant and despite a flurry of research back in the 90's and early 2000's the exact mechanism of action(s) remain uncertain. Zinc, like selenium, is known to have a narrow range between too little for optimal nutrition and too much resulting in toxicity. Caution is advised at supplementing this mineral above that in a well prepared feed and your trace mineral block.
DrO


Theriogenology. 2011 Apr 15;75(7):1201-10. Epub 2011 Feb 4.
Effect of sod (superoxide dismutase) protein supplementation in semen exten ders on motility, viability, acrosome status and ERK (extracellular signal-regulated kinase) protein phosphorylation of chilled stallion spermatozoa.

Cocchia N, Pasolini MP, Mancini R, Petrazzuolo O, Cristofaro I, Rosapane I, Sica A, Tortora G, Lorizio R, Paraggio G, Mancini A.
Source

Department of Veterinary Clinical Sciences, University of Naples Federico II, Naples, Italy. ncocchia@unina.it
Abstract

New studies are underway to find new methods for supporting longer storage of cooled stallion semen. It is known that high concentrations of reactive oxygen species (ROS) cause sperm pathology. The metalloprotein superoxide dismutase (SOD) is responsible for H(2)O(2) and O(2) production, by dismutation of superoxide radicals. The aim of this study is to assess the quality of chilled stallion semen processed with extenders containing SOD at different concentrations as antioxidant additives. A total of 80 ejaculates collected from 5 standardbred stallions was divided into 5 aliquots treated as: native semen (control 1); native semen diluted 1:3 with Kenney semen extender (control 2); spermatozoa diluted after centrifugation in extender without (control 3) or with SOD at 25 IU/ml (experimental 1) or 50 IU/ml (experimental 2). Each sample was analyzed for motility, viability and acrosome status, immediately after semen preparation and again after storage at 5 °C for 24 h, 48 h and 7 2h. Acrosome integrity was evaluated by Chlortetracycline (CTC) and Fluorescent-labeled peanut lectin agglutinin (PNA-FITC conjugated staining). A proteomic approach of quantifying extracellular signal regulated kinase (ERK) was also evaluated as an indirect indicator of oxidative stress. In all samples sperm progressive motility and sperm acrosomal integrity showed a significant reduction between fresh and cooled spermatozoa at 24 h, 48 h and 72 h. Quality parameters of sperm were significantly higher (Progressive Motility P < 0.01; Viability P < 0.001) in aliquots supplemented with SOD. ERK phosphorylation was statistically higher (P < 0.01) in aliquots without SOD. The Authors concluded that addition of SOD to semen extenders improves the quality of chilled equine semen and reduces ERK activation.

Theriogenology. 2011 Apr 15;75(7):1319-26. Epub 2011 Feb 4.
Effect of dietary antioxidant supplementation on fresh semen quality in stallion.

Contri A, De Amicis I, Molinari A, Faustini M, Gramenzi A, Robbe D, Carluccio A.
Source

Department of Veterinary Clinical Sciences, University of Teramo, Teramo, Italy.
Abstract

In this study, the effect of dietary supplementation of organic selenium, vitamin E, and zinc on raw semen characteristics was evaluated. Ten stallions with normal fertility were divided into two groups: a control group (CG), in which standard diet was provided, and a treated group (TG), in which the standard diet was supplemented with 1500 mg of α-tocopherol acetate, 360 mg of zinc, and 2.5 mg of organic selenium on a daily basis. Semen parameters on fresh semen were evaluated three times in all stallions before antioxidant supplementation (T0) and 30 (T1), 60 (T2), and 90 (T3) d after supplementation. Dietary supplementation with experimental antioxidants resulted in a significant increase in average path velocity (121.9 ± 3.1 μm/sec in TG vs 118.9 ± 4.3 μm/sec in CG), straightness (86.2 ± 2.4 % vs 82.6 ± 3.9 % in TG and CG respectively), viability (75.6 ± 10.2 % in TG vs 72.3 ± 6.9 % in CG) and total seminal plasma antioxidants levels (2.7 ± 0.5 mmol/l vs 1.9 ± 0.4 mmol/l in TG and CG respectively) while progressive motility 69.7 ± 11 % vs 62.2 ± 9.3 % in TG and CG stallions respectively) and abnormal sperm morphology (8.2±1.5 % in TG vs 14.4±4 % in CG) significantly improved in treated stallions after 60 d of supplementation. In contrast with previously reported in other species, a negative effect of antioxidant supplementation on semen concentration was recorded in the TG. A positive correlation between progressive motility and total antioxidants in seminal plasma in both treated and control stallions suggested that motility is affected by oxidative-antioxidative status, and that dietary antioxidant supplementation could increase the ability of spermatozoa to contrast reactive oxygen species or the ability of seminal plasma to reduce the oxidative stress. The improvement of semen parameters after antioxidant supplementation was not linear, and after 30 d (or 60 d for some parameters), a further increase was not noted. This evidence suggested that in our standard conditions, dietary intake of these antioxidants could be slightly under the dietary requirement and further evaluation of the actual nutrition requirements of organic selenium, zinc, and vitamin E in the stallion are needed.
Member:
canter

Posted on Wednesday, Jul 13, 2011 - 7:12 am:

Dr O, is it your reco to supplement with Vit E even in a non-breeding horse, then? This time of year, my mare is on good pasture, but I am wondering if I should put her on Vit E once the pasture is gone, aprox October thru April. She is 22 and I have no intentions of breeding her, but certainly want her in optimal health. She is fed, along with 24/7 pasture, free choice decent quality hay and a quality feed. She continues to be sound, so is worked 3-4 days a week.

Thank you,
Fran
Member:
judyhens

Posted on Wednesday, Jul 13, 2011 - 1:29 pm:

Hi Dr. O:
The statement: "In contrast with previously reported in other species, a negative effect of antioxidant supplementation on semen concentration was recorded in the TG" is worrisome to me. It makes me think supplementation is counterproductive - at least for this one factor. Is this your take? We feed Omolene 200 to our stallions and have very high conception rates. Do you know if it contains the needed anti-oxidants in appropriate amounts? Thanks,
Judy
Moderator:
DrO

Posted on Thursday, Jul 14, 2011 - 11:37 pm:

Hello Judy,
Supplementation in horses in this study at these levels was beneficial. There could be many reasons why other species have reacted differently Judy. I don't know if that feed has antioxidants in optimal amounts, indeed this study suggests further work needs to be done to determine the amounts. However it is important to remember that the majority of antioxidants come from the forage, so the quality of the forage should be your first concern. I think our numbers published in our articles on vitamins and minerals may be the best available at this time.
DrO
Moderator:
DrO

Posted on Thursday, Jul 14, 2011 - 11:41 pm:

Fran, it depends on several factors. You will find my recommendations for supplementing Vitamin E (and all other vitamins and minerals) in the Nutrition Overview article.
DrO
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