Vitrification advantages in relation to the conventional freezing in sheep ejaculates

Abstract

Forty sheep ejaculates were used to evaluate the vitrification advantages in relation to the conventional freezing. From each ejaculate, the volume, concentration and normal sperm were determined, with values of 0.8 mL, 1519X10⁶ and 95 %, respectively. Subsequently, each ejaculate was divided into two fractions of equal concentration, one to freeze and another to vitrify. Zero point five mL straws were used for freezing and 60 μL drops for vetrification. Sperm concentration in both methods was 50x10⁶ sperm/mL. Before and after cryopreservation, the progressive mobility (PM) was evaluated in fresh semen and it was 81 %. There was a difference (p<0.05) in relation to the cryopreserved semen, since mobility was greater (p<0.05) in thawed sperm (50 %) than in heated sperm (36 %). When analyzing viability results, a significant decrease (p<0.05) was observed in fresh semen (70 %), compared to the thawed (51 %) and heated sperm (54 %). When evaluating the acrosomal status and sperm viability, there were differences (p<0.05) between the fresh sperm (64 %) with respect to the thawed (45 %) and heated (47 %) in the live sperm with acrosomal reaction (VCA). This did not happened in the live sperm without acrosomal reaction (VSA) (6 %, 6 % and 7 %, respectively), in the dead acrosome-reacted sperm (MCA) (19 %, 29 % and 27 %, respectively), and in the dead sperm without acrosomal reaction (MSA) (11 %, 19 % and 18 %, respectively). It is concluded that, although both cryopreservation techniques showed similar results, vitrification has certain advantages such as that it requires less work time, material and equipment, decreasing the cost of the process and it can be applied in any laboratory.