Development of an effective diluent for the transport of rabbit semen

This thesis examined the effect of chilled storage on the in vitro quality and in vivo fertility of rabbit semen over 96h. Flow cytometric analyses determined that a tris-citric acid-glucose (TCG) extender containing 69.38mM glucose and storage at 15°C better preserved in vitro sperm quality than a concentration of 33.3mM glucose or 5°C, respectively, but preservation at 5°C resulted in lower H2O2 production than 15°C from 72h (P0.05) after 72h but fertility significantly declined with 15°C-stored spermatozoa. Supplementation of the diluting medium with the antioxidant quercetin, but not methionine, significantly improved H2O2 production with only high concentrations of quercetin (100-200µM) providing adequate protection against oxidative stress to result in similar levels of H2O2 production at both 5°C and 15°C after 96h (P>0.05). Dilution of semen to a concentration of 15x106 spermatozoa/mL prior to chilling negatively impacted tMOT but also reduced H2O2 after 48h, while the opposite was true for spermatozoa stored at 60x106 spermatozoa/mL. Moreover, H2O2 production and plasma membrane instability were reduced by the storage of diluted semen in straws rather than tubes (P<0.05). After 72h of semen storage, quercetin-supplemented spermatozoa resulted in more pregnancies (54.9%) than the control (no antioxidant; 48.0%). Fertility of does inseminated with spermatozoa stored at 30 or 60x106 spermatozoa/mL did not significantly differ immediately following semen collection (0h) or after 72h. However, at 96h the highest kindling rate was achieved in does inseminated with the lower dose of chilled semen (7.6%) with no live births resulting from semen stored at 60x106 spermatozoa/mL. The findings of this thesis describe a protocol for the storage and transport of ejaculates of high quality or genetic value between rabbit farms for up to 72h

Total motility and flow cytometric results from experiment 4.

<p>Post-thaw motility (A) and proportion of spermatozoa with intact membranes and acrosomes (B) from data pooled across 0, 2 or 4 hours post-thaw with incubation at 37°C of rabbit spermatozoa frozen in diluent containing 50 mM glucose as the sole carbohydrate source (Control; TCG; ●), a combination of 25 mM glucose and 25 mM sucrose (TCGS low; ■), or a combination of 50 mM glucose and 50 mM sucrose (TCGS high;▲). Each point represents datum from a replicate and the horizontal lines represent range around the mean. Superscripts represent significant differences within time points between treatment groups.</p

Motility kinematics from experiment 1.

<p>Motility kinematics from experiment 1.</p