25 A preliminary study of the effects of breed and nanowater as extender diluent on ram semen characteristics post-thawing

Abstract

This study examined the effect of genotype and extender diluent on the characteristics of frozen-thawed ram semen. Twenty ejaculates collected from 10 rams aged 4-12 years (2 Polish Lowland (PON), 4 synthetic line BCP (Berrichon du Cher × Charolais × PON/Polish Merino), and 4 SCP (Suffolk × Charolais × PON/Polish Merino) in mid-breeding season were divided into six equal portions each and frozen in semen extender prepared by mixing commercial Triladyl extender (MiniTub GmbH) with deionized water (Aqua Purificata, Prolab) or nanowater (NW; deionized water declusterized in a cold plasma generator for 15, 30, 45, 60, or 90 minutes (15’, 30’, 45’, 60’, or 90’, respectively); Nanotechnology Systems) and Gallus domesticus egg yolk (1:3:1 vol/vol/vol). All semen samples were evaluated for progressive motility (Sperm Class Analyzer) and sperm morphology (Nikon Eclipse 80i microscope, Nikon Corp.). In addition, the ex situ survival time at 37°C and extender content of ALT (alanine transferase), ALP (alkaline phosphatase), and aspartate aminotransferase were measured, and the numbers of apoptotic, necrotic, and live spermatozoa were determined post-thawing with flow cytometry (BD Accuri™ C6 Plus, Becton Dickinson). Data were analysed by two-way analysis of variance and least significant difference test (SigmaPlot, Systat Software Inc.). The PON exceeded (P < 0.05) SCP rams in the occurrence of mid-piece and double tail defects using NW30’ and NW45’ extenders. The proportion of spermatozoa with proximal droplets was greater (P < 0.05) in PON than in SCP or BCP rams with NW15’ and NW30’ extenders, respectively, but the percentage of sperm with detached heads was greater (P < 0.05) in BCP and SCP compared with PON using NW15’ extender. Overall, spermatozoa in PON rams’ semen had survival times greater by 25-50 min (P < 0.05) compared with those for semen from BCP and SCP synthetic lines. The ALT levels were significantly elevated in SCP compared with PON and BCP rams only in NW90’ extender. The numbers of necrotic spermatozoa were greater (P < 0.05) in SCP and BCP compared with PON rams, and the numbers of apoptotic spermatozoa were greater (P < 0.05) in BCP than in SCP rams with NW45’, NW60’, and NW90’ extenders. Live spermatozoa were more prevalent (P < 0.05) in PON than in BCP rams in NW45’ extender post-thawing. To summarise, semen from PON rams had higher survival times and fewer spermatozoa with detached heads but more mid-piece defects and sperm with double tails post-thawing compared with BCP and SCP breeds. The number of necrotic cells was greater in semen from BCP and SCP rams compared with PON. It can be concluded that breed-related differences in post-thaw sperm morphology were apparent in extenders containing NW15-60’, whereas the variations in cell necrosis/apoptosis were primarily seen with the use of NW45-90’ extenders.