Science and Tech Correspondent
Some chickens are bred specifically for the purpose of laying eggs. In such cases, being hatched as a male is problematic. Male chicks serve no purpose in the egg-laying industry, and because they develop too slowly to be used for meat, they are usually killed soon after hatching. Many animal rights advocates have deemed such systematic slaughter methods, which include gassing and grinding, unethical. Much controversy has surrounded this practice; in response, both the German government and the United Egg Producers, a major cooperative of U.S. egg farmers, have vowed to cease the practice once alternate techniques become available.
At Dresden University of Technology in Germany, a team of researchers has developed an innovative method of sexing chick embryos early enough in development that only the female embryos are harvested and hatched.
The process utilizes Raman spectroscopy, a technique that can be used to establish differences in blood biochemistry between sexes. In male blood, there are unique sugars and proteins present, as well as a higher percentage of DNA than that of females.
The approach involves using a laser to cut a minor circle into the egg and removing a small piece of shell, exposing the embryo’s blood vessels. The Raman spectrometer detects the scattering that is produced by shining near-infrared light on the embryo. Algorithms are then used to assess sex.
These algorithms correctly identify embryo sex nearly 95 percent of the time. For reference, manually examining feathers or genitals yields an accuracy rate of 98 percent. The infrared light does not seem to pose any harm to the embryo, and the process is totally painless for the chicks. An impressive 81 percent of the eggs have been found to hatch normally, not far off from the 92 percent of control eggs.
A drawback of this technique is that although it is much less invasive, it is five to eight times more time-consuming than traditional sexing methods. The Dresden researchers are constructing an industrial prototype which will likely make the process more efficient. The team also suggests that this method may be more cost effective due to the few materials that are actually required.
There are additional approaches to determining the sex of chicks before hatching, but such procedures involve testing hormone levels or extracting DNA samples from the egg. These tests require embryos to be about nine days into development, when chicks are already sensitive to pain. Furthermore, retrieving a sample from the egg in order to perform chemical analyses is not generally practical from a manufacturing standpoint.
The spectroscopy technique shows great potential, but as with any newly developed technique, fine-tuning and further assessment is essential. Ideally, this spectroscopy method will become mainstream. If poultry companies were to adopt this way of embryonic sex determination, the unethical slaughter of billions of male chicks would be reduced dramatically.