Antimicrobial activity of tea tree and lavender essential oils and their effects on hatching performance and eggshell bacterial count of Japanese quail eggs

The objective of this work was to study the effect of tea tree (TTO) and lavender (LavO) essential oils instead of formaldehyde fumigation to disinfect the surface of fertilized eggshells. A total of 1050 fresh unwashed fertilized quail eggs were randomly divided into 7 groups and treated before incubation as follows: group 1 was untreated (negative control), group 2 was sprayed with 70% ethyl alcohol (positive control), group 3 was fumigated with formaldehyde gas (FF), groups 4-5 and 6-7 were sprayed with 2%, 3% TTO and 2%, 3% LavO, respectively. Spraying fertilized eggs with 3% TTO or LavO significant reduced (P < 0.05) egg weight loss and improved yolk sac absorption expressed as a decrease in the yolk sac remaining weight (P < 0.01), which coincided with increasing the percentage of embryonic weight at 14th day of incubation compared to the FF. TTO or LavO significantly boosted the hatching rate that correlated with significant reduction (P < 0.01) in embryonic mortality with preference for LavO. Spraying fertilized eggs immediately after collection with TTO or LavO significantly reduced (P < 0.01) total bacterial count on the eggshell surface compared to the FF. Thus, TTO and LavO can be used to disinfect fertilized eggs prior to incubation to improve hatching rates and chicks' quality upon hatching.