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The aim of this study was to identify the effects of adding quercetin (Q) to Tris extender in order to identify levels of oxidative stress in bull sperm after freeze thawing. Ejaculates were collected via artificial vagina from Holstein bulls. Semen was divided into five tools and diluted to a final concentration of 15 × 10 spermatozoa/ml with the Tris extender containing Q (25, 50, 100 and 200 μg/ml) and no additive (control; C). All examples were equilibrated at 4°C during 4 hr then were loaded into 0.25-ml straws and frozen using a controlled rate. Sperm motility and motility characteristics were determined using the computer-assisted semen analyser. Sperm membrane integrity was assessed using the hypoosmotic swelling test. Sperm chromatin integrity was investigated using the single cell gel electrophoresis. Total antioxidant capacities were performed colorimetrically. Q supplementation used as an antioxidant did not produce better results in the proportion of sperm progressive and total motility, plasma membrane integrity and sperm abnormalities. Q supplementation exhibited the favourable tail length, tail DNA and tail moment. In conclusion, when whole parameters are considered, Q25 can be added to the Tris extender due to its positive effect on sperm DNA integrity and no adverse effect on the progressive and total motilities of sperm.

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Electro-ejaculation is a technique used to collect semen from rams. The aim of the study was to evaluate the stress response and the oxidant/antioxidant levels during electro-ejaculation (EE) procedure in merino rams. To assess the effect of this technique, six 3-4 years old merino rams were subjected to semen collection by EE. The technique was applied one time in previously untreated animals. The studied parameters [Heart and respiratory rate, rectal temperature, white blood cell count (WBC), red blood cell count (RBC), hemoglobin (Hb) levels, hematocrit (Hct) value, blood malondialdehyde (MDA) and glutathione (GSH) concentrations, plasma cortisol, nitric oxide (NO), glucose, cholesterol and triglyceride concentrations as well as plasma total antioxidant status (TAS) and total oxidant status (TOS)] were measured before and immediately after electrical stimulation. Heart and respiratory rate, WBC, MDA, glucose, cholesterol and triglyceride concentrations as well as plasma TOS and cortisol concentrations were dramatically increased after EE procedure, whereas rectal temperature, TAS and GSH concentrations were significantly decreased. These results demonstrate that MDA, GSH, TAS and TOS were the most powerful markers for evaluating the oxidant/antioxidant status in merino rams. Furthermore, EE procedure was a stressful situation leading to an oxidative stress, which can be amplified by increased glucocorticoid secretion.

The present study was conducted to examine the protective roles of trolox and alpha-lipoic on post-thawed Pirlak ram sperm parameters, oxidative stress and DNA damage in non-breeding season. Semen samples from 5 healty Pırlak rams (2-3 years of age) were used in the study. Six ejaculates for each rams were collected and pooled. Ejaculates were split into three aliquots and diluted to a final concentration of 150x10 6 spermatozoa/ml with the base extender containing 1 mM alpha lipoic acid, 1 mM trolox and no additive (control) were cooled to 5 °C and equilibrated for 3 h then frozen in 0.25 ml French straws. Samples were thawed in 37 o C and evaluated in terms of spermatological parameters, DNA damage, oxidative stress. Sperm motility was increased, acrosome rate and DNA damage were decreased significantly (p<0.05) in ALA, head abnormal sperm rate and membrane integrity were increased, acrosome rate and DNA damege were decreased significantly (P < 0.05) in trolox when compared to the control group. Compared with the control group, reductions in spermatozoon MDA and GSH levels were statistically significant (P <0.05) in lipoic acid and trolox groups. Results of this study suggest that alphalipoic acid and trolox improve sperm parmeters, oxidative stress and DNA damage in non-breeding season.

This study aimed to investigate the effectiveness of using red pine bark tree extract (P; Pinus brutia Ten) as a TRIS extender in an attempt to prevent oxidative stress in bull spermatozoa after freezing. Semen specimens were obtained from Simmental bulls via an artificial vagina and pooled. They were separated into five specimens and diluted with Tris extender consisting of P (200, 100, 50 and 25 µg/ml) and P free (control; C) up to a final concentration of 16 × 106 per straw. All specimens were equilibrated for a period of 4 hr at a temperature of 4°C, following which they were filled in 0.25‐ml French straws and frozen. Addition of P resulted in favourable tail length in comparison with C (p < .05). The lowest malondialdehyde levels and the highest glutathione levels were detected in all P groups (p < .05). Supplementation with P did not show advanced results in terms of total, progressive sperm motility and total abnormality in comparison with C (p > .05). In conclusion, it has been shown that although P added to a Tris extender does not have a positive effect on sperm motility, it prevents chromatin damage by reducing oxidative stress, in addition to reducing head abnormalities when used at the amount of 50 μg/ml.

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