Thyme Essential Oil and Hyaluronic Acid as Natural Disinfectant Alternatives for Broiler Breeder Fertile Eggs: Effects on Eggshell Microbial Load, Embryonic Viability and Hatchability
Sinan Vicil, Fatma Tülin Özbaşer Bulut, Muazzez Gürgan Eser, Hakan BulutABSTRACT
Background
Eggshell microbial contamination of fertile hatching eggs represents a major biosecurity concern in commercial poultry hatcheries because it can compromise embryonic viability, hatchability and chick quality. In commercial hatchery practice, broiler breeder fertile eggs are often stored before incubation to synchronize production schedules. However, prolonged storage may increase microbial contamination of the eggshell, deteriorate internal egg quality and reduce embryonic viability and hatchability.
Objectives
This study evaluated thyme essential oil and hyaluronic acid (HA) as natural alternatives to chemical disinfectants for sanitation of broiler breeder fertile eggs.
Methods
A total of 1800 Ross 308 hatching eggs were randomly assigned to four main treatments: untreated control, thyme essential oil (1%) emulsified with polysorbate‐20 (PS20), HA (0.1%) and thyme essential oil + HA. Eggs were stored for 0 or 14 days in a 4 × 2 factorial design. A PS20‐only vehicle control was included for selected comparisons.
Results
All sanitization treatments significantly reduced eggshell total aerobic bacterial counts compared with the untreated control ( p < 0.001). Storage for 14 days impaired internal egg quality, reducing albumen ratio, albumen index, yolk index and Haugh unit values, while increasing yolk ratio and albumen pH ( p < 0.001). Storage also reduced blastoderm viable cell number and increased dead cell number ( p < 0.001). Thyme essential oil produced the most favourable outcomes after storage, with higher hatchability of set eggs and hatchability of fertile eggs and lower embryonic mortality than HA‐treated eggs ( p < 0.05). Yolk malondialdehyde (MDA) levels were lower in the thyme group than in the control and HA groups after storage ( p < 0.01). Although HA reduced microbial load, it was associated with increased blastoderm dead cell counts and higher embryonic mortality after storage.
Conclusions
Thyme essential oil appears to be a promising residue‐free and biologically safe alternative to conventional chemical disinfectants for hatchery sanitation of broiler breeder fertile eggs.