Monitoring of Unhatched Eggs in Hermann’s Tortoise (Testudo hermanni) after Artificial Incubation and Possible Improvements in Hatching

SIMPLE SUMMARY: Hermann’s tortoises (Testudo hermanni) are common and popular pets. Their life expectancy is over 80 years. The major threats to these tortoises include loss of natural habitat, pollution, urbanization, tourism, road deaths, the pet trade, and possible transmission of various infectious diseases. Health problems can begin during artificial incubation and last a lifetime. For this reason, it is necessary to breed healthy hatchlings, and tortoise welfare will increase in parallel. Conditions for hatching and control of egg failure must be controlled. The presence of unfertilized and infected eggs in the lowest possible numbers is important for successful hatching. These parameters can be improved by monitoring breeding parents. Proper hatching will keep many tortoises alive and allow them to live long healthy lives and is essential for tortoise welfare allowing a more economical method of breeding. In this study, the causes of embryonic mortality in Hermann’s tortoises (Testudo hermanni) during artificial incubation on a large farm in Slovenia were determined. Possible improvements in Hermann’s tortoise hatching and methods to increase animal welfare were described. ABSTRACT: The causes of embryonic mortality in Hermann’s tortoises (Testudo hermanni) during artificial incubation were determined. Total egg failure at the end of the hatching period was investigated. The hatching artefacts represented 19.2% (N = 3557) of all eggs (N = 18,520). The viability rate of incubated eggs was 80.8%. The eggs, i.e., embryos, were sorted according to the cause of unsuccessful hatching and subsequently analyzed. Some of the eggs were divided into two or more groups. Unfertilized eggs were confirmed in 61.0%, infected eggs in 52.5%, and eggs in various stages of desiccation in 19.1%. This group also included mummified embryos. Pseudomonas aeruginosa, Bacillus sp., Purpureocillium lilacinum, and Escherichia coli were frequently confirmed in infected eggs. Embryos were divided into three groups: embryos up to 1.0 cm—group 1 (2.2%), embryos from 1.0 cm to 1.5 cm—group 2 (5.4%) and embryos longer than 1.5 cm—group 3 (7.3%) of all unhatched eggs. Inability of embryos to peck the shell was found in 1.3%. These tortoises died shortly before hatching. Embryos still alive from the group 2 and group 3 were confirmed in 0.7% of cases. Dead and alive deformed embryos and twins were detected in the group 3 in 0.5% and 0.1% of cases, respectively. For successful artificial hatching, it is important to establish fumigation with disinfectants prior to incubation and elimination of eggs with different shapes, eggs with broken shells, and eggs weighted under 10 g. Eggs should be candled before and periodically during artificial incubation, and all unfertilized and dead embryos must be removed. Heartbeat monitor is recommended. Proper temperature and humidity, incubation of “clean” eggs on sterile substrate and control for the presence of mites is essential. Monitoring of the parent tortoises is also necessary.