Effect of different semen extenders for the storage of chilled sperm in Tigrina (Leopardus tigrinus).

To enhance the conservation of endangered populations, the present study aimed to evaluate whether Tigrinas (Leopardus tigrinus) sperm could be conserved under refrigeration for short periods while maintaining sufficient quality for use in assisted-reproductive techniques (i.e., cryopreservation, in vitro fertilization). For this purpose, semen samples from 15 Tigrinas individuals were submitted to conventional and functional tests after different cooling periods (4 °C; 0, 12, and 24 hours postcooling), using TCM 199 (TCM), Ham's F10 (HAM), Ham's F10 with bovine serum albumin (HBSA), and Tris-citrate egg yolk (TEYC) extenders. In a second step, semen cooled using TEYC was supplemented with reduced glutathione (GSH) at different concentrations (0, 0.5, 1.0, and 1.5 mM). TEYC yielded superior results compared with TCM, HAM, and HBSA even after 24 hours of cooling in regard to the sperm motility index (SMI-TEYC: 50.2 ± 1.7%), high mitochondrial activity (TEYC: 51.4 ± 1.9%), plasma membrane integrity (TEYC: 53 ± 2.1%), and DNA integrity (TEYC: 56.3 ± 2.9%). In regard to the concentration of thiobarbituric-acid-reactive substances (TBARS), TEYC (1900.1 ± 341.4 ng/106 spermatozoa) showed higher levels compared with the other extenders (HAM: 638.7 ± 121.6 ng/106 spermatozoa; HBSA: 468.7 ± 95.6 ng/106 spermatozoa; TCM: 169.6 ± 31.6 ng/106 spermatozoa). However, GSH therapy had no effect. In conclusion, the TEYC extender may be useful in maintaining sperm parameters of Tigrinas for up to 24 hours at 4 °C. Furthermore, these results allow the transport of this material at a minimum quality to be further used for artificial insemination, in vitro fertilization, and the development of semen cryopreservation protocols.

Roles of lipid peroxidation and cytoplasmic droplets on in vitro fertilization capacity of sperm collected from bovine epididymides stored at 4 and 34 degrees C.

Sperm recovery from the cauda epididymis can be very advantageous, for example, in case of the unexpected death of a genetically highly valuable animal, for preserving endangered species, or when the collection of sperm by other means becomes impossible. Studies indicate that epididymides stored at cooler temperatures result in better quality sperm. One of the factors that could negatively affect sperm viability during storage is lipid peroxidation, in which the sperm membrane's ability to resist attacks by reactive oxygen species (ROS) plays an important role. Another factor is the presence of cytoplasmic droplets, which appear in high numbers in epididymal sperm, and are known to influence oxidative stress. The objectives of this study were: to determine whether the post-slaughter storage temperature of the epididymis would effect the sperm membrane's resistance to lipid peroxidation and/or the sperm cell's fertilizing capacity in vitro and to elucidate the role played by the cytoplasmic droplets. Forty-eight testicles with epididymides (24 bulls) were collected following slaughter, and divided into two groups. One testicle from each pair was stored at 4 degrees C, and the other at 34 degrees C, for 2h, after which sperm was collected from the caudae epididymides. Sperm concentration was measured, and an aliquot containing 10(8)sperm was subjected to induced lipid peroxidation with ferrous sulphate and ascorbate (37 degrees C, 2h). Subsequently, thiobarbituric acid reactive substances (TBARS), as an index of lipid peroxidation, were measured. A second aliquot of the same sample was used in a routine in vitro fertilization performed in duplicate. Sperm from caudae epididymides stored at 34 degrees C resulted in lower rates of total blastocyst formation and had a higher percentage of distal droplets, when compared to sperm from epididymides stored at 4 degrees C (21.2+/-2.42 and 71.8+/-4.7% versus 33.5+/-1.8 and 23.7+/-4.7%, respectively, P<0.05). Storage temperature had no effect on TBARS levels. For samples stored at 4 degrees C, TBARS were negatively correlated with distal droplets (r=-0.63, P<0.05) and positively correlated with proximal droplets (r=0.42, P<0.05). In conclusion, our results show that short-term storage of epididymides at 4 degrees C provided sperm of higher quality and in vitro fertilizing capacity than storage at 34 degrees C. Although resistance to oxidative stress could not be shown to directly influence these results, distal sperm droplets that appeared in high numbers in the cooled epididymal sperm samples, may have exerted an antioxidant effect. We hypothesize that this protection against ROS is one of the functions of distal sperm droplets in the epididymis.

Effects of dexamethasone treatment (to mimic stress) and Vitamin E oral supplementation on the spermiogram and on seminal plasma spontaneous lipid peroxidation and antioxidant enzyme activities in dogs.

The objective was to determine if treatment with dexamethasone (to mimic stress) has a deleterious effect on the spermiogram and on the composition of seminal plasma in the dog and whether adverse effects were reduced by oral supplementation with Vitamin E. Eighteen adult male Rottweiler dogs were randomly allocated in a 2 x 2 factorial treatment design (with or without dexamethasone treatment versus with or without Vitamin E supplementation). Dogs in the supplemented group received 500 mg of alpha-tocopherol (Vitamin E)/dog/day per os for 10 weeks. Dexamethasone (0.01 mg/kg/day i.m.) was given once daily for 7 days, starting 7 days after the onset of Vitamin E supplementation. Food intake, body condition score and body weight were assessed daily. Semen collections (digital manipulation) were performed twice weekly for 14 weeks and blood samples (for plasma concentrations of cortisol and testosterone) were collected once a week. Dexamethasone treatment significantly reduced ejaculate volume and increased thiobarbituric acid-reactive substances (TBARS) in the seminal plasma. In contrast, supplementation with Vitamin E increased sperm motility, vigor and concentration and decreased the percentage of major sperm defects. In conclusion, dexamethasone treatment (to mimic stress) had a deleterious effect on the spermiogram and on the seminal plasma lipid peroxidation in dogs; however, some of these effects were prevented by oral supplementation with Vitamin E.

Seasonal variation in semen quality in Bos indicus and Bos taurus bulls raised under tropical conditions.

In the present study, we tested the hypothesis that Bos taurus taurus bulls have greater reactive oxygen species (ROS) and lower activity of antioxidant enzymes in their semen than Bos taurus indicus bulls. Sixteen Simmental bulls (B. t. taurus) and 11 Nelore bulls (B. t. indicus) were managed extensively in a tropical environment. Semen was collected twice annually (summer and winter) for 2 consecutive years. Simmental bulls had significantly higher percentages of major sperm defects during the summer than the winter (20.3+/-3.1% versus 12.2+/-2.4%, respectively; mean+/-S.E.M.). There was an interaction of breed and season for minor sperm defects (P=0.037; highest in Nelore bulls in the summer) and an effect of season on total defects (P=0.066; higher in summer). To evaluate oxidative damage, malondialdehyde (lipid-peroxidation metabolite) concentrations were indirectly measured by semen concentrations of thiobarbituric acid reactive substances (TBARS); these were higher in summer than in winter (728.1+/-79.3ng/mL versus 423.8+/-72.6ng/mL, respectively; P=0.01). Glutathione peroxidase/redutase (GPx) activity in semen was higher in Simmental versus Nelore bulls (741.6+/-62.1 versus 510.2+/-62.8; P<0.01). However, superoxide dismutase (SOD), another antioxidant enzyme, was not significantly affected by breed or season. There were correlations between TBARS and sperm primary defects during the summer for both Simmental and Nelore bulls (r=0.59, P=0.021 and r=0.40, P=0.034, respectively), and between SOD and primary defects during summer for Simmental bulls only (r=-0.51, P=0.041). In conclusion, there was a higher level of lipid peroxidation (ROS) in semen of Simmental versus Nelore bulls; apparently the higher GPx activity in Simmental bulls was insufficient to avoid damage that occurred concurrent with increased ROS production during the summer.