Improving Reproductive Success in Tigers – Fellowship Training Grant

SUMMARY: Researchers will identify factors associated with the reproductive success and failure of Amur and Sumatran tigers housed in European zoos and create a biobank of cryopreserved sperm samples to assist with species conservation and breeding programs.  

THE PROBLEM: Breeding of zoo-housed Amur and Sumatran tigers is critical for long-term species survival. These tigers also serve as important genetic reservoirs for rapidly declining wild populations. However, breeding these conservation animals has been challenging due to low reproduction rates. Almost half of all zoo-based Amur and Sumatran tigers live in European zoos. Researchers fear that some zoo tiger populations will disappear in the next twelve years if we don't act now. Researchers need to know why these two types of tigers are not breeding well in captivity to help save the species.  

THE PROJECT: To solve this problem, researchers will look at the animal health records of previously chosen tigers to breed and information about their managed care conditions in zoos. Data will help identify factors that lead to successful breeding, informing breeding strategies to help increase tiger populations.    

The team will also check which tigers are bred. To do this, they will look at changes in the sexual hormones in the feces of the tigers and carry out complete reproductive health checks, which include blood tests, ultrasound scans, counting the cell types in vaginal swabs, and semen sampling and evaluation. These data will indicate the animal's reproductive status if any animals suffer from disease or other previously undetected issues.    

Finally, researchers will freeze collected tiger semen using methods that allow the cells to live indefinitely. The team will compare three different approaches to determine the most effective method for keeping semen alive after thawing to aid reproduction efforts.  

POTENTIAL IMPACT: Populations of zoo-housed tigers are rapidly declining globally, threatening the long-term conservation of these animals. The study will share new information on environmental and individual factors contributing to reproductive success with other zoo-based extensive cat facilities. Findings will help enhance tiger species' survival programs globally to mitigate extinctions.