Method for Early In-Ovo Sex Determination
Currently, in Germany alone, approximately 40 million male chicks from laying hen lines are culled annually immediately after hatching and killed byCO₂ gassing or in a homogenizer in accordance with the Animal Welfare Slaughter Ordinance. The issue of culling unwanted male day-old chicks affects all areas of layer hen production, including the organic sector, but is increasingly raising ethical and legal concerns. However, practical alternatives to the culling of male day-old chicks have not yet been available in layer breeding. The goal of our research project is to develop a practical method that allows for reliable sex determination even before the chicks hatch. To this end, the sex will be determined using optical spectroscopy on day 3 of incubation, when the embryos are not yet capable of feeling pain.
In Raman spectroscopy, monochromatic light is directed onto the sample, and the spectrum of the scattered light is analyzed. The structure of molecules can be unambiguously determined from the bands in the Raman spectrum. When ultraviolet (UV) light is used to excite Raman scattering, information from DNA and proteins in particular is amplified by the so-called resonance effect. However, by using lower-energy near-infrared light, this measurement principle can also be applied to in-ovo sex determination. For this purpose, the Raman scattered light from the blood of embryos incubated for approximately 72 hours is recorded and spectrally resolved. The Raman spectra of male blood cells exhibit slightly stronger signals in the nucleic acid region compared to those of female blood cells. These signals differ significantly and can therefore be used for sex identification.
Several years ago, we developed an optical-spectroscopic method for the early detection of the sex of chicken embryos. Sex is determined automatically on day 4 of incubation with a high accuracy of approximately 95%. This method is based on molecular markers in the embryonic blood vessels. Contactless optical access to the vessels is achieved through an opening in the eggshell measuring just a few millimeters within the air sac, ensuring that the embryo remains protected by the inner shell membrane. Several studies have also shown that this method does not affect the hatch rate or the subsequent development of the chicks in any way.
Currently, a method for sex determination in chicken eggs is being developed that does not require making a hole in the eggshell. This method utilizes modern imaging techniques such as UV/VIS and NIR spectroscopy. The biochemical basis for sex determination is, in turn, embryonic hemoglobin and associated metabolic processes.
To elucidate sex-specific metabolic processes and states in embryonic blood, research is being conducted on, among other things, molecular oxygenation mechanisms in the early chicken embryo and their sex-specificity. (Funded project by the Lower Saxony Ministry of Food, Agriculture, and Consumer Protection: “Molecular Mechanisms for Sex Determination in the Unhatched Chicken Egg”).
Collaborations
Agri Advanced Technologies GmbH, Visbek
Institute for Animal Welfare and Animal Husbandry, Friedrich Loeffler Institute, Federal Research Institute for Animal Health, Celle, Dr. rer. nat. habil. Thomas Bartels
Contact
© Jonas Golde, KSM
Mr apl. Prof. Dr. rer. nat. habil. Gerald Steiner
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Clinical Sensoring and Monitoring
Clinical Sensoring and Monitoring
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