Effect of seminal plasma removal before cryopreservation of bovine semen obtained by electroejaculation on semen quality and in vitro fertility

Abstract

Cryopreservation of bull semen is a common biotechnology procedure in cattle breeding. However, when the ejaculate is obtained by electroejaculation, wide variation is observed in the sperm/seminal plasma (SP) ratio that can affect the freezability of semen in this species. The removal of SP may improve the quality of frozen bull semen. The objective of this study was to evaluate the effect of SP removal from the ejaculate on the cryopreservation of semen from 38 Nellore bulls collected by electroejaculation. After collection, the ejaculate was divided into three aliquots: (1) control (N) diluted to a concentration of 60 × 10 spermatozoa/mL and frozen with SP; (2) centrifugation (C) at ×600g for 10 minutes and the pellet resuspended and frozen at the same concentration as N; and (3) filtration (F) through SpermFilter and sperm recovered and frozen at the same concentration as N. After thawing, sperm kinetics, plasma and acrosome membrane integrity, mitochondrial membrane potential, oxidative stress, and in vitro fertility were evaluated. Statistical analysis was performed using the SAS 9.2 package, and differences were considered significant when P < 0.05. Higher average path velocity and straight-line velocity were observed in the groups submitted to SP removal compared to the control group (P < 0.01). In contrast, filtered samples exhibited higher beat cross frequency, straightness, and linearity compared to the other groups. Plasma membrane integrity was reduced when SP was removed, but lower oxidative stress was observed in groups C and F (34.91 ± 2.95% and 31.63 ± 2.95%, respectively) compared to group N (57.39 ± 2.95%). However, the percentage of hatched blastocysts was similar in the N and F groups (21.22 ± 1.05% and 24.00 ± 1.05%, respectively) and higher compared to group C (18.83 ± 1.05%). In conclusion, removal of SP by centrifugation for bull semen freezing reduced the rate of in vitro-produced embryos, whereas filtration of prefrozen semen was found to be an efficient alternative in terms of semen freezability and in vitro production of bovine embryos.

Comparison of two methods of seminal plasma removal on buffalo (Bubalus bubalis) sperm cryopreservation

“…When both (plasmatic and acrosomal) membranes were evaluated, filtration resulted in greater damage, in accordance to a similar study in cattle (Campanholi et al, 2017). As this method of filtration was developed and efficacy has been demonstrated in stallions (Alvarenga et al, 2012), we infer that differences in seminal characteristics between buffaloes and stallions may have contributed to the results obtained in the present study.…”

Evaluation of cooling and freezing systems of bovine semen

“…A disadvantage of programmable cryopreservation units is their high cost (Abud et al, 2014), while they have the advantage of being flexible and permitting to alter the curve until the best results are achieved, with adaptation to the diluent, cryoprotectant or any other factor that influences the result (Forero-Gonzalez et al, 2012). Several studies have used programmable units for the cryopreservation of semen (Carvalho et al, 2010;Leite et al, 2010;De Andrade et al, 2011;Franco et al, 2014;Campanholi et al, 2017).…”

The influence of caffeine supplementation and concerted utilization of enzymatic and mechanical semen liquefaction on freezability of dromedary camel spermatozoa

“…The removal of seminal plasma prior to cryopreservation of semen was recently studied in different species [13] , [14] . Semen centrifugation is a reliable approved technique in stallions’ semen processing, to overcome the negative effects of seminal plasma during cryopreservation [15] , and to adjust dose concentration [16] .…”