56 COMPARISON OF 4 DIFFERENT DILUENT AGENTS ON CRYOPRESERVATION OF SEMEN FROM UNIMPROVED INDIGENOUS SOUTH AFRICAN GOATS

Abstract

The cryopreservation process is one of the most crucial factors that affect the post-thaw quality of frozen goat semen. The aim of this study was to compare 4 different semen diluents (Tris-BSA, Tris-yolk, Bioxcell®, and Ovixcell®). A total of 5 indigenous bucks were used as semen donors. Semen was evaluated for macroscopic and microscopic characteristics. Semen was pooled and diluted randomly in each of the 4 different extenders. Semen samples were equilibrated for 3 h at 5°C. After equilibration, samples were loaded into 0.25-mL straws and placed into the controlled-rate programmable freezer using a customized freezing curve (from 5 to –5°C at 4°C min–1, –5 to –110°C at 25°C min–1, and then from –110 to –140°C at 35°C min–1). Data was analysed with the aid of the statistical program GenStat®, using a complete randomised design. Following fresh semen dilution with Tris-BSA, Tris-yolk, Bioxcell®, and Ovixcell®, the sperm progressive motility percentage was 41.5 ± 4, 43.5 ± 7, 48.6 ± 5, and 50.2 ± 7%, respectively (P > 0.05). In addition, the live normal sperm percentage following fresh semen dilution was 59.2 ± 5, 49.2 ± 6, 57.8 ± 5, and 54.4 ± 3% for Tris-BSA, Tris-yolk, Bioxcell®, and Ovixcell®, respectively (P > 0.05). After thawing semen samples frozen either with Tris-BSA, Tris-yolk, Bioxcell®, or Ovixcell, the sperm progressive motility percentage was 5.3 ± 2, 1.6 ± 1, 10.6 ± 2, and 13.3 ± 3%, respectively (P < 0.05). Furthermore, the live normal sperm percentage following thawing was 19.1 ± 3, 14.3 ± 3, 39.6 ± 6, and 37.1 ± 3% for Tris-BSA, Tris-yolk, Bioxcell®, and Ovixcell®, respectively. In conclusion, sperm progressive motility percentage was reduced following the freezing-thawing process, irrespective of the type of extender used. The Bioxcell® and Ovixcell® extenders showed to be better for South African indigenous goat semen cryopreservation purposes.