Follicular fluid stimulates capacitation and acrosome reaction in alpaca sperm (Vicugna pacos)

The follicular fluid exerts an effect on the sperm capacitation of several species; however, these effects vary according to species, both in the sperm motility and in the subsequent acrosome reaction. In this study, the effect of alpaca follicular fluid (aFF) on the motility and acrosome reaction of alpaca spermatozoa was observed, using follicular fluid of three follicle sizes: small (<3 mm), medium (3-6 mm) and large (>6 mm), in a concentration of 30%. Sperm motility at the first hour of incubation with aFF of small follicles was 48.0%, with aFF of medium follicles it was 43.33% and with aFF of large follicles, it was 34.53%, while control averaged 26.00%. At the second hour, control achieved an average of 28.13%, treatment with aFF from small follicles showed an average of 46.53%, with aFF from medium follicles it was 40.00% and with aFF from large follicles it was 35.60%. The acrosome reaction after 4 hours of incubation was 30.06% for control, whereas for aFF of small follicles it was 66.3%, with aFF of medium follicles it was 58.86% and for aFF of large follicles, it was 67.63%. In the case of sperm motility, a significant difference is demonstrated for all treatments in relation to the control at the first hour, whereas only the treatments with aFF of small and medium follicles show a significant difference with respect to the control at the second hour. In the case of the acrosome reaction, all treatments with follicular fluid show a significant difference with respect to the control. It was concluded that alpaca follicular fluid favours sperm capacitation and the acrosome reaction in alpaca spermatozoa.