Non-enzymatic extraction of spermatozoa from alpaca ejaculates by pipetting followed by colloid centrifugation

Viscous camelid ejaculates present problems for sperm handling and sperm preservation. In the present study, a technique that had been used for dromedary camel semen was tested with alpaca semen. Ejaculates (n=9) were collected by artificial vagina at San Marcos University, Lima, and were liquefied by gentle pipetting in tris-citrate-fructose. Half of the sample was prepared by Single Layer Centrifugation (SLC) through a colloid; the other half was centrifuged without colloid as a control. Each control and SLC sample was then split into two parts; one part was stored cooled for 24 h at 5 °C and the other part was frozen, resulting in 4 treatments for each ejaculate. All samples were evaluated for sperm motility, hypoosmotic swelling test (HOST), plasma membrane integrity, and morphology, immediately after centrifugation and again after storage Total motility and plasma membrane integrity were greater in samples prepared by SLC than controls (motility 72±13% vs. 57±7%; plasma membrane integrity 63±13% vs. 54±8%, for SLC and controls respectively). Normal morphology and HOST were not different between treatments (65±13 vs. 61±13% and 42±6 vs. 39±10%, for SLC and controls respectively). After 24 h cooled storage, motility and plasma membrane integrity were greater for SLC samples (motility: 51±16 vs. 34±15%; p<0.001; membrane integrity: 51±15 vs. 40±18%; P < 0.05 for SLC and controls, respectively); HOST (40±14 vs. 34±11%) and normal morphology (67±13 vs. 63±14%) were not different between treatments. Sperm quality decreased considerably after cryopreservation (P<0.001 for all parameters); however, motility (P<0.01), plasma membrane integrity (P<0.05) and morphology (P<0.05) were higher for SLC than for controls. These results indicate that alpaca spermatozoa can be extracted from semen using a combination of pipetting and SLC, potentially with a beneficial effect on sperm quality. Samples could be stored cooled for 24 h, retaining better motility than controls; motility and plasma membrane integrity were greater in SLC samples than controls after freezing and thawing but the freezing protocol requires improvement.