IXth International Conference on Boar Semen Preservation 2019

Implications of boar sperm kinematics and rheotaxis for fertility after preservation (#3)

Sean Fair 1 , J Romero-Aguirregozcorta 2
  1. Laboratory of Animal Reproduction, Department of Biological Sciences, School of Natural Sciences, Faculty of Science and Engineering, University of Limerick, Limerick, Ireland
  2. Department of Physiology, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU), Leioa, Bizkaia, Spain

Artificial insemination (AI) is single most important assisted reproductive technique devised to facilitate the genetic improvement of livestock. In the swine industry, it has broadly replaced natural service over the last number of decades which has been made possible by the high pregnancy rates and litter sizes obtainable with semen extended, up to, and sometimes beyond 5 days. Central to achieving good reproductive performance is the ability of boar studs to monitor semen quality, the basis of which has long been the assessment of sperm motility by subjective and, more recently, by more objective computerised systems. In this review, we summarise the literature on the relationship between sperm motility and kinematic parameters and field fertility. We discuss how this relationship is dependent on factors such as the when in vitro assessments relative to the timing of AI are made, the viscosity of the media and the use of standard operating procedures. We discuss the emerging evidence of the importance of sperm rheotaxis and thigmotaxis as long distance sperm guidance mechanisms, which enable motile functional spermatozoa to avoid the backflow of fluid, mucus and semen from the sow’s uterus in the hours post AI, facilitating the establishment of sperm reservoirs in the oviducts. We summarise the literature on the use of microfluidics in studying sperm rheotaxis in vitro and how these systems, when combined with techniques such as lensless microscopy, have the potential to offer more physiological assessments of boar spermatozoa swimming patterns.  Finally, we propose possible future avenues of further investigation