Effect of cryoprotectant type and equilibrium temperature on cryopreservation of alpaca sperm (Vicugna pacos)

Abstract

The objective of this study was to determine the effect of glycerol (GL), dimethyl sulfoxide (DMSO) and dimethylformamide (DMF) at temperatures of 5 °C and 16 °C of equilibrium on sperm quality, after cryopreservation. 6 males were used in the semen collection, motility parameters were evaluated with the CASA system, viability, acrosomal integrity and mitochondrial activity by flow cytometry in fresh and thawed semen. We collected 30 ejaculates of which 10 were discarded for not fulfilling (volume ≥ 1 ml and total motility ≥ 60 %), the 20 ejaculates were mesclo in a tube to form pool carrying out the assessment of the initial quality of fresh semen, obtaining a total motility (MT) 61,6 ± 3,4%, progressive motility (MP) 51,7 ± 3,7%, viability 78,1 ± 9.1%, mitochondrial activity (MA) 77,4 ± 7,7 and acrosomal integrity 88,9 ± 11,5%. After cryopreservation no equilibrium temperature effect was observed, independently of cryoprotectant in the parameters of seminal quality. Cryoprotective effect (P≤ 0.05) was observed, presenting superior values in the sperm conserved in GL with respect to the rest of cryoprotectants, with significant differences (P ≤ 0,05) in MT, MP, viability and AM and without significant differences in acrosomal integrity. The equilibrium temperature of 16 °C was effective for cryopreservation of alpaca sperm. In addition, the 5% GL preserved better the functional characteristics of sperm compared to 7% (DMF and DMSO).