Effects of different doses of trehalose supplementation in egg yolk extender in frozen-thawed Angora buck semen

Few studies have been done on the effects of trehalose supplementation in the cryopreservation of Angora buck semen. The objective of present study was to investigate the effects of the addition of trehalose at different doses in semen extenders, on in vitro semen quality parameters, anti-oxidant enzymes activities and DNA damage after the freeze-thaw process in Angora buck semen. Semen samples from 5 mature Angora bucks (3 and 4 years of age) were used in this study. The bucks, belonging to the Livestock Central Research Institute were maintained under uniform breeding condition. A total number of 40 ejaculates were collected twice a week from the bucks using an artificial vagina, during the breeding season and the semen pooled to minimize individual variation. Each pooled ejaculate was split into 7 equal aliquots and diluted (37 °C) with base extenders supplemented with the trehalose (12.5, 25, 50, 75, 100 and 150 mM), and a base extender with no additives (control). Diluted samples were aspirated into 0.25 ml French straws, and equilibrated at 5 °C for 4 h and then were frozen at a digital freezing machine. The freezing extender supplemented with 50 mM trehalose led to the greatest percentages of CASA motility (53.6 ± 4.69), in comparison to the other groups after the freeze-thawing process (P < 0.05). The addition of different doses of trehalose did not provide any significant effect on the percentages of post-thaw sperm motion characteristics (VAP, VSL and LIN), compared to the control (P > 0.05). The freezing extender with 150 mM trehalose group led to the highest percentages of acrosome abnormalities (P < 0.05) and 50 mM trehalose group had the lowest percentages of total abnormalities (P < 0.001), in comparison to the others. There were no significance differences in the DNA integrity among treatment groups (P > 0.05). The different doses of trehalose did not show any effectiveness on the maintenance GPx, LPO, GSH, CAT and total antioxidant activities, when compared to the control (P > 0.05). Therefore, the additions of 50 mM and 75 mM doses of trehalose will be useful in increasing post thaw motility on Angora buck semen.