Factors affecting in vitro oocyte maturation in Southern white rhinoceros ( Ceratotherium simum simum )

BACKGROUND: factors that could potentially affect in vitro oocyte maturation (IVM) in the Southern white rhinoceros (SWR). OBJECTIVE: To identify predictors of oocyte maturation following ovum pick-up (OPU) procedures performed on a large number of rhinoceros under different management conditions. METHODS: Data from 85 OPU procedures between November 2018 and June 2023 were obtained for this study. A total of 23 factors (three animal, four environmental, 16 laboratory) were evaluated as potentially affecting IVM success. RESULTS: Of the 85 procedures performed on 59 SWR, a total of 265 oocytes were collected with a median of two oocytes (range 0-18) per OPU. Eighteen (18) of the procedures yielded 0 oocytes. The overall maturation rate was 30% (80/265), and six identified factors had significant univariate associations with maturation outcome, of which three remained in the multivariable model. CONCLUSION: < 0.05).