Seasonal variation in nuclear DNA integrity of frozen-thawed spermatozoa from Thai AI swamp buffaloes (Bubalus bubalis).
In this study, we investigated the susceptibility of frozen-thawed swamp buffalo sperm nuclear DNA to undergo controlled acid-induced denaturation in situ, as analysed by flow cytometry, and aimed to correlate the results with sperm head morphology over three seasons in tropical Thailand. Artificial insemination (AI) doses (n = 218) from 18 AI buffalo sires, prepared between 1980 and 1989 and 2003 and 2005, were tested and compared among three seasons, the rainy season, July-October; winter, November-February; and summer, March-June. The overall mean of DNA fragmentation index (DFI) (+/- SD) was 1.84 +/- 1.68%, range from 0.19 to 7.92%, with 0.221 +/- 0.021 of the x-DFI ranging from 0.190 to 0.350 and 0.023 +/- 0.009 of the SD-DFI ranging from 0.010 to 0.070. The DFI was consistently low (range 1.40 +/- 0.21% to 2.16 +/- 0.21%; LSM +/- SEM), with x-DFI ranging from 0.216 +/- 0.003 to 0.225 +/- 0.003 and SD-DFI ranging from 0.022 +/- 0.001 to 0.024 +/- 0.001 across the seasons. The DFI was low enough to be related to high fertility potential. However, DFI values varied statistically among seasons, being lower in the rainy season (1.40 +/- 0.21%, P < 0.05) than in winter (2.16 +/- 0.21%) or summer (2.00 +/- 0.20%), and were also affected by the year of semen collection and processing (P < 0.001). The proportion of morphologically abnormal sperm head shapes was low, with no significant differences between seasons. However, DFI was significantly related to the proportion of loose abnormal sperm heads (r = 0.27, P < 0.01). In conclusion, frozen-thawed swamp buffalo sperm chromatin integrity is not seriously damaged by cryopreservation or affected by the seasonal variations in temperature and humidity seen in tropical Thailand.
Koonjaenak
S
S
Division of Comparative Reproduction, Obstetrics and Udder Health, Department of Clinical Sciences, Swedish University of Agricultural Sciences, Box 7054, SE-75 007, Uppsala, Sweden.
Johannisson
A
A
Pongpeng
P
P
Wirojwuthikul
S
S
Kunavongkrit
A
A
Rodriguez-Martinez
H
H
D000818:Animals; D000835:Animals, Wild; D002020:Buffaloes / Q000502:physiology*; D002980:Climate; D053938:DNA Fragmentation; D005434:Flow Cytometry / Q000379:methods / Q000662:veterinary; D007315:Insemination, Artificial / Q000662:veterinary; D008297:Male; D012621:Seasons; D012661:Semen / Q000166:cytology / Q000502:physiology; D012662:Semen Preservation / Q000379:methods / Q000592:standards / Q000662:veterinary*; D013077:Sperm Head / Q000648:ultrastructure; D013094:Spermatozoa / Q000166:cytology / Q000502:physiology*; D013785:Thailand