Sperm DNA damage is related to field fertility of semen from young Norwegian Red bulls

Abstract

Flow cytometry was utilised for the first time to independently measure five sperm parameters of individual spermatozoa of bull ejaculates to differentiate between outcome successes after artificial insemination (AI). These parameters included plasma membrane and acrosome integrity, mitochondrial functionality and DNA damage measured by sperm chromatin structure assay (SCSA) and terminal deoxynucleotide transferase-mediated dUTP nick end labelling (TUNEL) assays. For each parameter, results of 142 ejaculates (30 bulls) were ranked into three groups according to their flow cytometric measures: (1) ejaculates with the 25% lowest measures; (2) the 50% middle measures; and (3) the 25% highest measures. In total, 20 272 first-service inseminations (18 ;10(6) spermatozoa per AI dose) were performed, where fertility was defined as non-return within 60 days after first insemination. While plasma membrane and acrosome integrity, and mitochondrial functionality were not significantly related to fertility, data from SCSA and TUNEL assays were significantly associated with fertility. Ejaculates in SCSA group 1 had higher odds of AI success (1.07, 95% CI = 1.02-1.12), whereas those in group 3 had lower odds of AI success (0.94, 95% CI = 0.89-0.99), compared with the average odds of all three groups. Ejaculates in group 2 did not have significantly higher odds of AI success compared with the average odds. For TUNEL-positive spermatozoa, the odds of AI success was higher in group 1 compared with the average odds (1.10, 95% CI = 1.02-1.13), whereas odds of AI success in groups 2 and 3 were not significant compared with the average odds. In conclusion, despite the high number of spermatozoa per AI dose from high-quality bulls, both SCSA and TUNEL assays were valuable measures in this study for evaluating sperm quality in relation to fertility after AI.

Use of immobilized cryopreserved bovine semen in a blind artificial insemination trial

“…This result is in accordance with earlier studies showing that in vitro assessment of viability and acrosome integrity had no correlation to field fertility [17,31,32], whereas others have shown an association [16,33,34]. The reason for these conflicting results could be due to the relatively high number of sperm cells in the semen samples of both B and SV used for AI, i.e., there are still enough sperm cells capable of fertilizing the egg even in the samples with the poorest quality in this study.…”

“…In accordance with other studies, bull significantly affected the proportion of AIL spermatozoa (%) postthaw [31].…”

Sperm DNA assays and their relationship to sperm motility and morphology in bulls (Bos Taurus)

“…In the present study, SCSA assay was reliable for distinguishing different qualities of DNA in the sperm cells. This assay has long been considered valuable for measuring DNA quality and its relationship to fertility has been reported for many species (Evenson et al, 1980;Ballachey et al, 1987;Evenson et al, 1994;Sailer et al, 1996;Love and Kenney, 1998;Larson et al, 2000;Januskauskas et al, 2001;Januskauskas et al, 2003;Waterhouse et al, 2006;Morrell et al, 2008;Didion et al, 2009;Nordstoga et al, 2013;Oleszczuk et al, 2013). Therefore, it was used in the present study as a reference assay to which the other assays could be compared.…”

“…The SCSA identifies the ratio of ssDNA (abnormal) to dsDNA (native) in the exposed toroid linker regions, but not in the more compact toroids (Shaman and Ward, 2006). This assay has been widely used to evaluate sperm DNA quality in men (Evenson et al, 1980), bulls (Ballachey et al, 1987(Ballachey et al, , 1988Januskauskas et al, 2001;Januskauskas et al, 2003;Waterhouse et al, 2006;Fortes et al, 2012;D'Occhio et al, 2013), stallions (Love and Kenney, 1998) and boars (Evenson et al, 1994). In contrast, the Comet assays (i.e., neutral and alkaline) reportedly allow stain access to both the toroid and toroid linker regions (Shaman et al, 2007) for identification of ssDNA and dsDNA breaks.…”

<b>Impacto da qualidade espermática sobre a fertilidade <i>in vivo</i> em bovinos:</b> contribuição de marcadores mitocondriais e subpopulações espermáticas

“…Para sêmen de bovinos ainda é controverso. O índice de fragmentação de DNA foi menor em touros de alta (3,10±0,16%) do que de baixa fertilidade (4,04±0,15) (P<0,01) (GLIOZZI et al, 2017), mas as taxas de DFI% reportadas para sêmen congelado de bovinos são baixas (6,1±3,1%) (WATERHOUSE et al, 2006), confirmando a baixa vulnerabilidade do DNA aos danos pelo processo de congelação e descongelação (GLIOZZI et al, 2017).…”