Abstract:
BACKGROUND : Rhinoceros are currently one of the most threatened mammal species globally. Slow population growth, increased
poaching and habitat destruction have led to increased conservation efforts for each species. Assisted reproductive technologies
(ART) have been implemented in an attempt to aid reproductive outputs for the conservation of these endangered species.
Developing species-specific ART programmes for wildlife have been challenging. Temperature control during oocyte recovery is
essential for ensuring in vitro success.
OBJECTIVE : This study is the first to investigate the effect of enema warming prior to trans-rectal ovum pick-up (OPU) on in vitro
oocyte maturation in Southern white rhinoceros (Ceratotherium simum simum).
METHODS : OPUs were performed on 20 rhinoceros cows from three different game farms in South Africa; oocytes were transported
to one of two in vitro fertilisation laboratories for culture. The enema fluid was either warmed to 32 °C or not warmed prior to the
OPU. Location of the farm, the different laboratories, ambient temperature, season, aspiration probe temperature, media type and
enema temperature were investigated as predictor variables for oocyte maturation success.
RESULTS : After considering all other potential covariates, warming of the enema fluid was the only independent predictor of in vitro
oocyte maturation success during this study.
CONCLUSION : Oocytes retrieved from rhinoceros cows that received an enema warmed to 32 °C were 2.3 times more likely to mature
in vitro compared to oocytes from cows that received an unwarmed enema; the findings can be implemented in other rhinoceros
ART programmes and in conservation efforts of other endangered mammalian species.
