Effect of Bioxcell® and Triladyl® Extenders and Removal of Seminal Plasma on Equilibrated and Cryopreserved Semen from South African Unimproved Indigenous Bucks

Abstract

The objectives of the study were to evaluate the effect of two extenders (Triladyl® and Bioxcell®) and the removal of seminal plasma on indigenous buck’s semen. Semen was collected from six indigenous bucks using an electro-ejaculator. Raw semen was pooled and randomly allocated into six groups as follows: (i) Raw non-washed, (ii) Raw washed, (iii) Triladyl®-washed, (iv) Triladyl®-non-washed, (v) Bioxcell®-washed and (vi) Bioxcell®-non-washed. Both the Triladyl® and Bioxcell® washed semen samples groups were diluted (1:4 v/v) with Phosphate Buffered Saline (PBS) then centrifuged at 1500x g for ten min and seminal plasma was removed. The groups were analysed for spermatozoa motility rates using Computer-Aided Sperm Analysis (CASA). The spermatozoa viability was assessed using Eosin-Nigrosin, acrosome integrity using Spermac, chromatin structure using Acridine Orange, and mitochondria using JC-1 staining solutions. Semen samples were diluted (1:4 v/v) as follows: Triladyl® (washed and non-washed) or Bioxcell® (washed and non-washed) and then equilibrated at 5°C for 2 hours. Equilibrated semen samples in 0.25 mL French straws were placed 5 cm above a Liquid Nitrogen (LN2) vapour for 10 min, and stored for one month. Frozen semen straws per treatment group were thawed at 37°C for 30 seconds. Significant differences among the mean values of semen parameters were determined by Tukey’s test using ANOVA, GLM procedure of SAS version 12.1 of 2010. The spermatozoa progressive motility rate in non-washed semen extended with Bioxcell® was significantly higher (89.6±7.5a) compared with that of non-washed Triladyl®, washed Bioxcell® and Triladyl® (P<0.05). Live spermatozoa percentage in washed semen extended with Triladyl® extender was reduced (27.7±17.1) significantly compared with the other groups (P<0.05). There was a lower percentage of spermatozoa with high mitochondrial membrane potential in non-washed and washed semen extended with Bioxcell® (39.5±23.2 and 37.9±28.6, respectively) compared with that of non-washed and washed semen extended with Triladyl® (P>0.05). The spermatozoa progressive motility rate in non-washed semen extended with Bioxcell® (58.5±10.0) extender was significantly higher compared with that of the other groups (P<0.05). There was a higher live and normal spermatozoa percentage in non-washed semen extended with Bioxcell® (45.7±21.2) compared with that of the other groups (P<0.05). In conclusion, Washing of seminal plasma in semen extended with Triladyl® was not essential, as it lowered viability, progressive motility and chromatin membrane integrity prior and post-cryopreservation. However, Bioxcell® extender was found to be more suitable for preserving spermatozoa during equilibration and freezing/thawing process of non-washed and washed buck semen.