Ultrastructure and fertilizing ability of Limousin bull sperm after storage in CEP-2 extender with and without egg yolk

Effectiveness of cauda epididymal plasma-2 and lecithin based diluents to minimize abnormality of sexing albumin spermatozoa during cold storage

Background and Aim:

Lecithin based diluent such as AndroMed, is a semen diluent made without animal components to prevent the risk of disease transmission, while glutathione (GSH) is an intracellular non-enzymatic antioxidant that prevents cell damage due to reactive oxygen species. Meanwhile, the specific impact of AndroMed and GSH combinations on spermatozoa abnormalities has not been fully studied. Therefore, this study aims to determine the effect of using cauda epididymal plasma-2 (CEP-2) and AndroMed diluents with or without the addition of GSH on the abnormalities of sexing semen of Ongole crossbred bulls in cold storage.

Materials and Methods:

This study used a factorial completely randomized design 2×2, the first factor was types of diluent and the second was with or without the addition of GSH. Observation of spermatozoa abnormalities was carried out at a storage time of 0-5 days using 297 ejaculations of liquid semen, with 100 spermatozoa observed per smear of each ejaculate. Furthermore, the data were analyzed using a two-way analysis of variance and the significant threshold (p-value) for statistical analysis was set at <0.05.

Results:

The results showed that there was a significant difference (p<0.05) between AndroMed and CEP-2 in minimizing the abnormalities of upper layer spermatozoa (X), with parameters DH and AD on day 0, damage of spermatozoa (DMR) on days 1-5, and dag-like defect (DLD) on day 5. Furthermore, spermatozoa abnormalities in the lower layer (Y) showed a significant difference between diluents in the parameters of AD on day 1, DMR on days 0-5, and DLD on days 1-5. The significant difference between with or without the addition of GSH in the X sperm was observed in the DH parameters on day 0 and DMR on 5, while there was no significant difference in the Y sperm.

Conclusion:

Based on the results, AndroMed has the potential to minimize spermatozoa abnormalities compared to CEP-2 diluent in sexed liquid semen. Therefore, AndroMed diluents with or without the addition of 1 mM GSH have no significant effect on spermatozoa abnormalities.

Evaluation of bull spermatozoa during and after cryopreservation: Structural and ultrastructural insights

Semen cryopreservation is a well-established procedure used in veterinary assisted reproduction technology applications. We investigated damaging effects of cryopreservation on the structural and ultrastructural characteristics of bull sperm induced at different temperatures and steps during standard cryopreservation procedure using transmission (TEM) and scanning electron microscopy. We also examined the effect of cryopreservation on sperm DNA and chromatin integrity. Five healthy, fertile Friesian bulls were used, and the ejaculates were obtained using an artificial vagina method. The semen samples were pooled and diluted in a tris-yolk fructose (TYF) for a final concentration of 80 × 106 spermatozoa/ml. The semen samples were packed in straws (0.25 ml), and stored in liquid nitrogen (-196°C). Samples were evaluated before dilution, just after dilution (at 37°C), at 2 h and 4 h during equilibration, and after thawing (37°C for 30 s in water bath). In association with step-wise decline in motility and viability, our results showed that the plasma membrane surrounding the sperm head was the most vulnerable structure to cryo-damage with various degrees of swelling, undulation, or loss affecting about 50% of the total sperm population after equilibration and freezing. Typical acrosome reaction was limited to 10% of the spermatozoa after freezing. We also observed increased number of mitochondria with distorted cristae (15%). Chromatin damage was significantly increased by cryopreservation as evident by TEM (9%). This was mainly due to DNA breaks as confirmed by Sperm Chromatin Structure Assay (SCSA) (8.4%) whereas the chromatin structure was less affected as evaluated microscopically by toluidine blue staining. We concluded that, using standard cryopreservation protocol, the most pronounced damage induced by cryopreservation is observed in the plasma membrane. Further improvement of cryopreservation protocols should thus be targeted at reducing plasma membrane damage. Acrosomal, mitochondrial and chromatin damage are also evident but appear to be within acceptable limits as discussed.