Effect of LDL Addition Into Selected Bull Sperm Diluters on Resistance of Spermatozoa Against Cold Shock

Abstract

The aim of work was to determine the effect of LDL cholesterol addition into selected diluters on the resistance of spermatozoa against cold shock and on their short-term survivability during cold test. The hypothesis was that the addition of LDL cholesterol will positively affects sperm resistance to cold shock and ensures a higher survivability of spermatozoa during short-term cold survival test. Four bulls of different breeds and ages, from the same sire insemination center were used. A total of eight semen collections were processed. Each ejaculate was divided into 6 portions (3 controls and 3 samples). Three commercially produced diluters, AndroMed®, Bioxcell®, and Triladyl® were used, each in standard and LDL enriched variants. In the case of AndroMed® or Bioxcell®, 6% of LDL was simply added. In Triladyl®, 10% of LDL replaced the standard egg yolk component. Spermatozoa resistance to cold shock was evaluated by the percentage of live sperm using Eosin-Nigrosine staining. The results showed the influence of bull individuality as an important factor. It is possible to recommend Bioxcell® with addition of LDL cholesterol in 6% concentration, which survivability was 69.17% at the beginning of the test, and 52.94% after 2 hours of incubation.

Low Density Lipoprotein - important player in increasing cryoprotective efficiency of soybean lecithin-based bull semen extenders

“…1). This is contrary to LDL effect before cryopreservation on PM assessed by our previous study (Beran et al, 2016) and other studies e. g. (Hu et al, 2011), which revealed its significant effect on PM but also after thawing. Above all, our results are in compliance with a study (Amirat et al, 2005) where the authors provided the closest insight using scanning electron microscopy into the LDL function in PM.…”

“…1) crucial for successful binding and fertilization of oocytes (Layek et al, 2016). Importantly, the same concentration of LDL in the same extender was confirmed as significantly favourable for PM integrity after collection (Beran et al, 2016). This is supported by evidence that LDL had a positive indirect influence on maintaining the functional status of PM due to its high binding affinity to BSP proteins (Lusignan et al, 2011), thereby preventing destabilization (Srivastava et al, 2013).…”

“…The fact that artificial liposomebased extender did not exhibit such protection during semen chilling showed that other methods to improve the cryoprotective properties of bull semen extenders could be found. Our previous studies (Beran et al, 2013;Stadnik et al, 2015;Beran et al, 2016) pointed to the positive effect of LDL addition to SL based extenders already before cryopreservation. Our preliminary results (Simonik et al, 2016) indicated the effect of LDL on the sperm motility after cryopreservation.…”

“…Similar mechanisms of soybean lecithin and LDL pointed out their presumed synergistic cryoprotective activity. The potential of the common action of LDL and soybean lecithin was determined by our studies, which focused on the prevention cold shock during the equilibration of spermatozoa (Beran et al, 2013;Stadnik et al, 2015;Beran et al, 2016). The preliminary results of this effect during cryopreservation were also positive , however, this study cover only limited number of animals and sperm parameters.…”