- Epididymal spermatozoa were harvested from male alpacas and frozen after extension and cooling to 4°C in citrate-, Tris- and lactose-based diluents (Experiment 1) and as pellets in 0.25- and 0.5-mL straws on either dry ice or over liquid nitrogen vapour (Experiment 2) to determine the effects diluents and packaging on their motility and acrosome integrity. In Experiment 1, sperm motility was higher after cooling to 4°C and after freeze–thawing (0 but not 3 h post-thaw) for spermatozoa extended in the lactose- than the citrate- or Tris-based diluent (P < 0.05). Post-thaw acrosome integrity after cooling to 4°C and post-thaw (0 h) was reduced for spermatozoa frozen in citrate- compared with lactose- or Tris-based diluents, but was similar for all groups 3 h after thawing. In Experiment 2, sperm motility immediately after thawing was higher for pellet freezing than for 0.25- or 0.5-mL straws on dry ice or liquid nitrogen vapour (P < 0.05), although by 3 h post-thaw motility was similar for pellets and straws (P > 0.05). Acrosome integrity was similar for all groups immediately after thawing and 3 h post-thaw. Cryopreservation of epididymal alpaca spermatozoa is feasible, with retained motility and acrosome integrity post-thaw. Freezing as pellets in a lactose-based diluent is recommended.
- Two experiments were conducted to determine the effects of glycerol concentration and Equex STM® paste on the post-thaw motility and acrosome integrity of epididymal alpaca sperm. In Experiment 1, epididymal sperm were harvested from male alpacas, diluted, and cooled to 4 °C in a Lactose cooling extender, and pellet-frozen in a Lactose cryodiluent containing final glycerol concentrations of 2, 3, or 4%. In Experiment 2, epididymal sperm were diluted in Biladyl®, cooled to 4 °C, stored at that temperature for 18–24 h, and further diluted with Biladyl® without or with Equex STM® paste (final concentration 1% v:v) before pellet freezing. In Experiment 1, sperm motility was not affected by glycerol concentration immediately (2%: 16.1 ± 4.6%; 3%: 20.5 ± 5.9% and 4%: 18.5 ± 6.6%; P > 0.05) or 3h post thaw (< 5% for all groups; P > 0.05). Post-thaw acrosome integrity was similar for sperm frozen in 2% (83.6 ± 1.6%), 3% (81.3 ± 2.0%) and 4% glycerol (84.8 ± 2.0%; P > 0.05) but was higher 3h post-thaw for sperm frozen in 3% (75.7 ± 3.8%) and 4% (77.2 ± 4.1%) than 2% glycerol (66.9 ± 2.7%; P < 0.05). In Experiment 2, sperm motility was higher immediately after thawing for sperm frozen in the presence of Equex STM® (Equex®: 21.5 ± 3.5%; control: 14.4 ± 2.1%; P < 0.05) but was similar at 3h post-thaw (P > 0.05). Acrosome integrity was similar for sperm frozen with or without Equex STM® paste immediately (control: 89.6 ± 1.2%; Equex®: 91.1 ± 1.4%; P > 0.05) and 3 h post-thaw (control: 69.3 ± 3.7%; Equex®: 59.9 ± 5.8%; P > 0.05). Sperm cryopreserved in medium containing 3–4% glycerol and 1% Equex STM® retained the best motility and acrosome integrity, even after liquid storage for 18–24 h at 4 °C prior to cryopreservation.
- Alpacas have become more popular during the last decades. The herds have been built up by importing live animals since reproductive biotechnologies, for example artificial insemination and semen preservation, are not well-developed in this species. A major problem is the viscosity of the seminal plasma which hinders processing or evaluation of the semen. Enzymes have been used to deal with the viscous seminal plasma but they may damage spermatozoa or render them incapable of fertilization. The use of reproductive biotechnologies would permit the introduction of new genetics without the need to import live animals, thus improving animal welfare and reducing the risk of spreading diseases. Therefore, our aim was to improve reproductive biotechnologies to help develop the Swedish alpaca breeding industry. Laboratory techniques were performed to select the best spermatozoa with Single Layer Centrifugation (SLC), in order to improve cryopreservation. These techniques were developed first using bull semen. There was an improvement in sperm quality in the SLC-selected samples, particularly from poor quality semen. In addition, the SLC technique could be modified to process small volumes. Alpaca epididymides were obtained after routine castration for husbandry purposes, with the intention of comparing semen extenders using extracted epididymal spermatozoa. Most of the organs came from pre-pubertal animals and therefore did not contain spermatozoa. Nevertheless, a decision-making tool for alpaca husbandry under Swedish conditions was developed. We suggest a combination of testicular size and body condition score as a tool for decision-making in the selection of potential sires for animal husbandry under Swedish conditions. A phantom was designed and built to collect semen samples in Sweden, and semen collection trials were also performed in Perú. The advantages and disadvantages of different semen collection techniques were evaluated. However, the problem with semen viscosity still has to be solved. Therefore a semen collection method should be established so that semen handling methods can be developed. We conclude that a phantom could be the best method to use for semen collection in Sweden, since it is a fairly simple technique and, as far as we are aware, there are no animal welfare concerns.