In ovo sexing of chicken eggs by fluorescence spectroscopy

Abstract

Culling of day-old male chicks in production of laying hen strains involves several millions of animals every year worldwide and is ethically controversial. In an attempt to provide an alternative, optical spectroscopy was investigated to determine nondestructively in ovo the sex of early embryos of the domestic chicken. The extraembryonic blood circulation system was accessed by producing a window in the egg shell and the flowing blood was illuminated with a near-infrared laser. The strong fluorescence and the weak Raman signals were acquired and spectroscopically analyzed between 800 and 1000 nm. The increase of fluorescence intensity between 3.5 and 11.5 days of incubation was found to be in agreement with the erythropoietic stages, thus enabling to identify hemoglobin as fluorescence source. Sex-related differences in the fluorescence spectrum were found at day 3.5, and principal component (PC) analysis showed that the blood of males was characterized by a specific fluorescence band located at ∼910 nm. Supervised classification of the PC scores enabled the determination of the sex of 380 eggs at day 3.5 of incubation with a correct rate up to 93% by combining the information derived from both fluorescence and Raman scattering. Graphical abstract The fluorescence of blood obtained in ovo by illumination of embryonic vessels with a IR laser displays spectral differences that can be employed for sexing of eggs in early stage of incubation, before onset of embryo sensitivity and without hindering its development into a healthy chick.

Nondestructive sex-specific monitoring of early embryonic development rate in white layer chicken eggs using visible light transmission

“…This result was consistent with the above explanation regarding increased blood production due to oestrogen synthesis receptors and enzyme production in females, which would result in higher blood levels and lower T575/T598 ratio. This findings agreed with what Galli et al (2017) reported, i.e. a steady-state increase in haemoglobin fluorescence in female embryos from d 4.5 to day 7.5.…”

“…Moreover, sexspecific development has been reported to occur from the onset of embryogenesis in domestic chickens with males developing faster than females during the first phase of incubation (∼30 h) due to over-expression of cellproliferation genes in males (Tagirov and Golovan 2015). This is in agreement with Galli et al (2017), who observed significantly higher haemoglobin fluorescence in male embryos at d 3.5, who used an in ovo fluorescence spectroscopic measurement of main vitelline vessels through an eggshell window.…”

Contactless in ovo sex determination of chicken eggs

“…Therefore, the source of this fluorescence and the possibility to exploit it for sex determination were further investigated [7]. First of all, it was observed that only the red blood cells display intense fluorescence, while all other embryonic and extraembryonic fluids and tissues give a Raman spectrum almost free from background.…”

The Ethics of Laying Hen Genetics

“…Current options for the cessation of the practice include in-ovo-sexing (Galli et al 2017;Weissmann et al 2013) or the development of dual purpose breeds suitable for both egg and meat production. However, in surveys of Dutch citizens, there was little consensus about acceptable alternatives (Leenstra et al 2011;Gremmen et al 2018).…”