Reproductive physiology of the female African lion (Panthera Leo), and development of artificial insemination protocols

Abstract

At present, most felid species are listed as Vulnerable or Endangered by the International Union for the Conservation of Nature (IUCN). Assisted reproduction techniques (ART), such as artificial insemination (AI), are extremely important for their conservation. However, ART overall success in non-domestic felids remains <25%. Thus, research on the specific feline reproductive physiology, and development of a model for application of ART into the breeding conservation of these species is needed. With that purpose, the African lion served as a large-felid-model species. Six lionesses were trained by positive reinforcement conditioning (PRCT) to voluntary allow frequent collection of blood samples and vaginal swabs. In parallel, their ovarian cycles were non-invasively monitored by behavioural observation and measurement of faecal steroid metabolite concentrations. This information was used to determine the optimum timing for AI in this species. Routine sampling by PRCT was possible after 20 weeks of training, enabling collection of about 750 vaginal swabs and 650 blood samples over 18 months. Revealed plasma and faecal oestrogen and progestogen profiles allowed identification of and differentiation between pregnancy and pseudopregnancy, but resulted inconclusive for oestrus detection. For the first time, the ovarian cycle of the African lioness was described from a detailed cytological point of view, including the report of Simonsiella spp. during oestrus, and a remarkably high number of neutrophils during proestrus in all females. Lastly, non-surgical AI with fresh semen in lionesses presenting natural heat was possible both, prior to and after ovulation induction with GnRH, resulting in the birth of the first lion cubs ever conceived by AI.