The effect of glycosaminoglycan enzymes and proteases on the viscosity of alpaca seminal plasma and sperm function.

In order to advance the development of cryopreservation and other assisted reproductive technologies in camelids it is necessary to eliminate the viscous component of the seminal plasma without impairing sperm function. It has been postulated that glycosaminoglycans (GAGs) or proteoglycans are responsible for this viscosity. This study investigated the effect of the GAG enzymes hyaluronidase, chondroitinase ABC and keratanase and the proteases papain and proteinase K on seminal plasma viscosity and sperm function in order to aid identification of the cause of seminal plasma viscosity and propose methods for the reduction of viscosity. Sperm motility, DNA integrity, acrosome integrity and viability were assessed during 2h incubation. All enzymes reduced seminal plasma viscosity compared to control (P<0.001) although papain was most effective, completely eliminating viscosity within 30 min of treatment. Sperm motility and DNA integrity was not affected by enzyme treatment. The proportion of viable, acrosome intact sperm was reduced in all enzyme treated samples except those treated with papain (P<0.001). These findings suggest that proteins, not GAGs are the main cause of alpaca seminal plasma viscosity. Papain treatment of alpaca semen may be a suitable technique for reduction of seminal plasma viscosity prior to sperm cryopreservation.