Sperm characterization and identification of sperm sub-populations in ejaculates from pampas deer (Ozotoceros bezoarticus)

Abstract

Pampas deer (Ozotoceros bezoarticus) is a native endangered species. Knowledge of the basic spermiogram characteristics and the morphometric descriptors is necessary to effectively develop sperm cryopreservation. In other species, sperm sub-population is related to sperm cryo-resistance. The objective was to provide a general description of the sperm, including sperm head morphometric descriptors, its repeatability, and the existence of sperm sub-populations. Sperm were obtained from adult males by electroejaculation during the breeding season. The motility score was 3.4±0.2 (mean±SEM) and progressive motility was 59.4±3.7%. Ejaculated volume was 413.9±51.0μl, the total number of sperm ejaculated was 321.2±55.4×106. Also, 63.3±3.1% of the sperm were morphologically abnormal and 23.7±2.3% had acrosome damage. The sperm head length was 7.6±0.01μm, width 4.4±0.01μm, area 28.1±0.07μm2 and the perimeter was 21.9±0.04μm. There was a positive relationship among morphometric descriptors and the motility score, overall motility and progressive motility. Also length (P=0.011), width (P=0.003), area (P=0.006) and perimeter (P=0.009) of sperm head obtained in two different collections were positively related. Overall, the low concentration, volume, overall quality and abnormal morphology, and wide variation of these variables may be a limitation for the development of sperm cryopreserved banks. There were three sperm sub-populations with different morphometric characteristics. The morphometric descriptors are maintained similarly among different collections.