Seasonal Variation in Nuclear DNA Integrity of Frozen–Thawed Spermatozoa from Thai AI Swamp Buffaloes (Bubalus bubalis)

Abstract

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.

Evaluation of postthaw sperm parameters and fertility of Cholistani service bulls

“…These results suggest that postthaw sperm parameters, especially PMI and DNA integrity of sperm, are reliable indicators of fertility, as has been suggested previously (27,28). In addition, this is supported by the highest fertility rate noticed in the present study for bulls KWC-24, KWC-25, and KWC-28 which revealed the highest DNA integrity of spermatozoa.…”

Effect of Cryopreservation on Apoptotic‐like Events and its Relationship with Cryocapacitation of Buffalo (Bubalus bubalis) Sperm

“…In the present study, DNA fragmentation assay based on TUNEL staining could not identify any significant changes in nuclear structures of cryopreserved buffalo sperm. A number of previous studies also reported that DNA integrity was unaffected during freezing and thawing of sperm in swamp buffalo (Koonjaenak et al. 2007), human (Duru et al.…”

Flow cytometry for the assessment of animal sperm integrity and functionality: state of the art

“…In humans, and only under certain conditions of assessment of fertility (assisted reproductive technology procedures), males with semen samples with more that 30% DNA fragmentation index were considered unable of establishing pregnancy. 103 In animals, where SCSA is the most widespread method to assess chromatin integrity among domestic animals, [104][105][106] particularly related to processed semen (including storage and cryopreservation), there is a relationship between chromatin damage and fertility, but thresholds are far from established with certainty. 11 Another parameter indicated by SCSA is the ratio of spermatozoa with high green fluorescence.…”