Syzygium aromaticum Essential Oil as a Safe Natural Solution to Control Bacteria in Hatching Eggs

The bacterial contamination of eggshells may be responsible for embryonic mortality, as may the contamination of chicks and broilers. Poor incubation results may be related to high levels of contamination that overcome the antibacterial defenses of the eggshell structure and the poultry's immune system. Although synthetic antibacterial formulations have demonstrated efficacy in controlling eggshell bacteria, they have also demonstrated toxicity to the embryo. In this study, we aimed to establish a safe and antibacterial topical protocol using <i>Syzygium aromaticum</i> essential oil (SAEO) to sanitize hatching chicken eggs. We evaluated the antibacterial capacity of this essential oil and used the 'hen's egg test on chorioallantoic membrane' (HET-CAM) model to measure its toxicity. Our results demonstrated the high effectiveness of SAEO in reducing the bacterial load on eggshells, suggesting that this natural compound is a promising egg sanitizer. However, although the HET-CAM model did not indicate signs of toxicity for pure SAEO, we recommend that its application, following dilution in grain alcohol, be carried out on the surface of eggshells and never directly in the internal embryonic compartment, owing to the toxicity of alcohol.