LAUSR

Semen extenders and seminal plasma are vital for cryopreservation of buck semen. The objectives of the study were to evaluate the effect of 2 extenders: Triladyl® (Minitube, Tiefenbach, Bavaria) and Bioxcell® (IMV, L’Aigle, France) and the removal of seminal plasma on buck semen. Six indigenous bucks were used in this study and 6 ejaculates were collected from individual bucks. The semen was pooled and then randomly allocated into 6 groups: (1) raw-washed, (2) raw-non-washed, (3) Triladyl®-washed, 4) Triladyl®-non-washed, (5) Bioxcell®-washed, and (6) Bioxcell®-non-washed. Spermatozoa viability was assessed using Eosin-Nigrosin and morphology using Spermac® (Vitrolife, Goteborg, Sweden) stains. The washed semen samples were all diluted into (1:4 v/v) with PBS and centrifuged at 1500 × g for 10 min. Semen samples were then extended with Triladyl® or Bioxcell® per treatment groups and equilibrated for 2 h at 5°C. The semen samples were loaded into straws per treatment groups and placed 5 cm above a liquid nitrogen vapour for 10 min and then stored at –196°C until use. After 1 month of storage, frozen semen straws per treatment group were thawed at 37°C for 30 s, and spermatozoa parameters were analysed post-thaw. 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 (SAS Institute Inc., Cary, NC, USA). There was a higher (P < 0.05) live and normal spermatozoa percentage in non-washed semen extended with Bioxcell® (45.7 ± 21.2) than the semen extended with Triladyl® (24.5 ± 22.2%). Live and normal spermatozoa percentages were drastically reduced in the Bioxcell® (5.2 ± 4.9) and Triladyl® (6.9 ± 8.6%) washed semen groups. There was a higher (P < 0.05) percentage of spermatozoa with head abnormalities in non-washed semen extended with Triladyl® (20.4 ± 10.2), compared with the semen extended with Bioxcell® (18.3 ± 12.4%) following freeze-thawing. There was a higher (P < 0.05) percentage of spermatozoa with head abnormalities in washed semen samples extended with Triladyl® (34.0 ± 16.0) compared with the semen extended with Bioxcell® (10.1 ± 7.0%). There were higher (P < 0.05) percentages of spermatozoa with coiled tail abnormalities in washed semen extended with Bioxcell® (65.4 ± 25.0) compared with Triladyl® (35.9 ± 21.6%). In conclusion, the liveability of spermatozoa was negatively affected by washing of semen extended with Bioxcell® and Triladyl® extender. Bioxcell® significantly increased tail abnormalities and Triladyl® gave less protection against head abnormalities following cryopreservation of South African unimproved indigenous bucks’ semen.