Author:

Keywords:

egg gases, egg incubation, gas chromatography - mass spectrometry, in ovo sexing, Volatile organic compounds, 1SC7219N|1SC7221N#54776441, EggTech-0000000028

Abstract:

Recently, the study on volatile organic compounds (VOCs) emitted from chicken hatching eggs gained increasing interest for non-invasive in ovo sexing. Traditionally, a solid-phase microextraction fiber is used to extract VOCs from an egg enclosed in a jar. Although its subsequent analysis on a gas chromatography-mass spectrometry (GC-MS) device reaches a desirable signal, eggs need to be sequentially extracted (e.g. delivering 7 measurements per day). Subsequently, this lengthy process limits the observation numbers and impacts statistical robustness. Therefore, we introduce a new extraction approach whereby a PDMS-coated stir bar (Twister®) is enclosed for two hours together with the egg. Resultantly, multiple eggs can be extracted in parallel. Furthermore, these Twisters® can be stored for multiple days and robotic sampling automatically analyzes these sorbents on the GC-MS, triplicating the measured eggs per day (e.g. 21 eggs vs. 7) and providing a similar signal relative to the fiber approach. We incubated 45 Isa Brown® eggs under standard conditions (37.7 °C, 50 % RH) and measured VOCs on even incubation days up to day 12. Egg breakout was performed on day 14 and fertilization and embryonic sex were verified. We used partial least squares discriminant analysis models to analyze the data and found that it was possible to robustly assess egg fertilization starting from day 6 with an accuracy of 100 %. Carboxylic acids were significantly higher in fertilized eggs due to the metabolic activity of the embryo, while most VOCs were more abundant in unfertilized eggs. We were not able to build robust sex determination models between days 0 to 12 with an accuracy higher than 76 %, although significant sex differences were observed over time. Aldehydes such as tetradecanal and pentadecanal were consistently higher in males and phenol was higher in females. These differences suggest that sexing models could potentially be improved by following the VOC profile of an egg over time. Overall, the new Twister® extraction method for analyzing VOCs in chicken eggs allows for the efficient assessment of fertilization and embryonic sex. Future work will involve reproducing experiments with larger sample sizes and optimizing data preprocessing and statistical analysis.