Influence of intrinsic and extrinsic factors on quality of Asian elephant semen – Current knowledge and new research directions

Abstract

Asian elephants (Elephas maximus) face persistent challenges across both natural habitats and managed environments. In zoological and conservation settings, elephant populations remain largely unsustainable, due to low reproductive rates, elevated calf mortality, suboptimal breeding management practices, and a high prevalence of chronic health conditions. Although substantial knowledge gaps remain in female elephant reproduction, greater insight into semen biology and semen quality is equally critical, given that existing evidence in that area is fragmented and has been difficult to translate into practical applications. A major unresolved challenge is the underlying cause of poor and inconsistent fresh semen quality, together with the marked fragility of elephant spermatozoa during handling, short-term storage, or cryopreservation. These limitations also continue to compromise semen preservation outcomes and may reduce the overall success of assisted reproductive technologies (ARTs). This review synthesizes current knowledge on elephant semen, including sperm and seminal plasma biology and physiology, and summarizes commonly used methods for semen collection, processing, and evaluation. Practical and refined methodological guidance is provided, with emphasis on rectal massage as the primary semen collection technique. By integrating evidence on intrinsic factors (age, reproductive anatomy, endocrine regulation, and musth-related changes) and extrinsic factors (semen handling practices, nutritional status such as body condition score, and seasonality) that may contribute to semen variability and reduced semen quality, this review identifies key knowledge gaps, highlights future research priorities, and provides practical recommendations to improve semen handling and preservation in elephants under human care.