A potential alternative entire culture system for psittacine embryos and the establishment of a detailed embryonal development table of cockatiels (Nymphicus hollandicus)

Abstract

This study aimed to establish an easy-to-use, alternative culture system for oocytes of endangered bird species (psittacids), allowing further oocyte cultivation without its eggshell from oviposition onwards. In such a culture system, eggs of endangered bird species can be cultivated despite defective eggshells, and the associated losses are minimized. It is also possible to conduct research and manipulations on the available germinal disc. Despite many efficient alternative breeding systems, especially for chicken and quail eggs, very few systems efficiently allow the entire embryonic development in a single design from egg laying to hatching. After successfully adaptation of a known an one-stage, alternative culture system with a replacement shell (surrogate) in chicken oocytes, this system was transferred to the smaller oocytes of cockatiels as a model species for psittacids. For better comparability of the culture system results, the Hamburger and Hamilton (1951) stages of classification were established for the cockatiel using 139 freshly laid cockatiel eggs. Afterwards, 68 freshly laid, fertilized cockatiel oocytes were cultured in quail surrogates. The development rate of the oocytes in this system was 89.7 %. Most developmental stages died before hatching. Though, one egg developed until the hatching of a chick and some until shortly before (four vital oocytes of 68 on incubation day 16). The median development of this oocytes was between the 3rd and 4th day of incubation (Hamburger and Hamilton stage 19). From the current point of view, this is the first described application of an alternative, complete culture system to a non-domesticated bird species in the available literature. However, improvement of the method is necessary to use this system in routine applications.