228 BOAR FERTILITY AND SPERM CHROMATIN STRUCTURE ASSAY DEFINED SPERM DNA FRAGMENTATION
D. P. Evenson A B , K. Kasperson A , R. L. Wixon B and B. A. Didion CA South Dakota State University, Brookings, SD, USA;
B SCSA Diagnostics, Brookings, SD, USA;
C Minitube of America, Verona, WI, USA
Reproduction, Fertility and Development 21(1) 212-212 https://doi.org/10.1071/RDv21n1Ab228
Published: 9 December 2008
Abstract
The sperm chromatin structure assay (SCSA) was used retrospectively to characterize sperm from 18 sexually mature boars having fertility information. Boar fertility was defined by farrowing rate (FR) and average total number of pigs born (ANB) per litter of gilts and sows mated to individual boars. The SCSA uses flow cytometry to evaluate the structural integrity of sperm nuclear DNA. In brief, aliquots of frozen/thawed semen were treated for 30 s with a pH 1.2 buffer that denatures sperm DNA at the sites of DNA strand breaks. The samples are then stained with acridine orange (AO) that intercalates into native, double-stranded DNA and fluoresces green under the flow cytometer laser beam. Broken and denatured single-stranded DNA associates with AO and then collapses, causing a metachromatic shift from green to red fluorescence. Five thousand sperm are measured per sample at rates of ~200 s–1, thus giving the data strong statistical robustness. This fact coupled with the precision of the AO/DNA biochemistry provides a CV ~2% between replicate samples. The SCSA parameters measured in this study were the %DNA fragmentation index (%DFI; percentage of sperm with fragmented DNA) and standard deviation of DFI (SD DFI). The %DFI and SD DFI showed the following significant negative correlations with FR and ANB; %DFI v. FR r = –0.55, P < 0.01, SD DFI v. FR r = –0.67, P < 0.002, %DFI v. ANB r = –0.54, P < 0.01, and SD DFI v. ANB r = –0.54, P < 0.02. A discrimination analysis was used to distinguish between the boar groups above and below 6% DFI. The variables most useful to discriminate between 2 groups were SD DFI, FR, and ANB. The average squared canonical correlation for SD DFI was 0.82, P < 0.0001. The average squared canonical correlation for FR and ANB was 0.45, P < 0.003 and 0.54, P < 0.001, respectively. Odds ratios for %DFI and SD DFI were 1.5 times (P = 0.0003, CI 1.22, 1.94) and 2.5 times (P = 0.0001, CI 1.87, 3.32), respectively.
