- Australia as a leader in the sheep industry has the experience, infrastructure, institutions, and assisted reproductive technologies required for genetic improvement of alpaca herds. With the development of artificial insemination, embryo transfer techniques, in vitro production of embryos (IVP) and the inauguration of a genetic improvement program for alpacas, it will be possible to develop a breed of extra fine Australian alpaca comparable to the alpaca kept by the Incas before the conquest in relatively few years.
- Semen preservation and artificial insemination in South American camelids are reviewed giving emphasis to work done in Peru and by the authors. Reports on semen evaluation and the preservation process indicate that semen of alpacas and llamas can be manipulated by making it liquid first. Collagenase appears to be the best enzyme to eliminate viscosity. Tris buffer solution maintains a higher motility than egg-yolk citrate, phosphate buffered saline (PBS), Triladyl, and Merck-I extenders. Cooling of semen took 1h after collected, and equilibrated with 7% glycerol presented a better motility and spermatozoa survival at 1,7,15 and 30 days after being slowly frozen in 0.25mL plastic straws. Trials of artificial insemination with freshly diluted semen and frozen–thawed semen are encouraging and needs to be tested extensively under field conditions. Recently, fertility rates varied from 3 to 67%. Semen preservation and most important, artificial insemination appear to be a reality, and could be used to improve the genetic quality of alpacas and llamas.
- Degelification of highly viscous alpaca semen was attempted using two enzymes: trypsin and collagenase. Dilution effect on artificial insemination was determined in alpacas. Semen from 4 male alpacas was collected, degelified, diluted, and inseminated into 80 female alpacas. Degelification was achieved adding trypsin and collagenase enzymes to fresh semen samples. Semen was diluted with egg-yolk glucose citrate to give concentrations of 4, 8, and 12 million spermatozoa/mL. Females were induced to ovulate with human chorionic gonadotropin and then inseminated deep into the uterine horns. Analysis of variance was used to determine differences in the effect of trypsin and collagenase on sperm acrosome and on motility and live spermatozoa. The chi-square test was used to determine differences in pregnancy of artificially inseminated females. Semen was degelified with different concentrations of trypsin and collagenase. There were differences (p< .05) in the pregnancy rate of female alpacas inseminated with 4 million (53.3%), 8 million (66.7%), and 12 million sperm/mL (61.5%). Alpaca semen may be degelified using trypsin and/or collagenase. It seems that 8 million sperm/mL is adequate for artificial insemination in alpacas.
Cryopreservation of Epididymal Alpaca (Vicugna pacos) Sperm: a Comparison of Citrate-, Tris- and Lactose-Based Diluents and Pellets and StrawsEpididymal 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.
Effect of Glycerol Concentration, Equex STM® Supplementation and Liquid Storage Prior to Freezing on the Motility and Acrosome Integrity of Frozen-Thawed Epididymal Alpaca (Vicugna pacos) SpermTwo 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.