The treatment of hatching eggs for the control of egg transmitted aspergillosis

Characterisation of the Mycobiota on the Shell Surface of Table Eggs Acquired from Different Egg-Laying Hen Breeding Systems

Microbial safety is an important factor contributing to the egg quality. During egg acquisition, there is significant risk of contamination of the eggshell surface with microscopic fungi. Mycelial hyphae may grow on the eggshell surface and penetrate into the egg content. However, there is no information on the populations of microscopic fungi on the eggshell surface and, consequently, on possible production of mycotoxins. Therefore, the aim of the study was to identify the species of microscopic fungi present on the eggshell surface acquired from different breeding systems and to measure the number of selected mycotoxins. The qualitative analysis resulted in the identification of 41 isolates on the surface of eggs. There were 7 isolates from the organic production system, 11 from the free-range production system, 14 from the deep litter indoor housing system and 9 from the cage farming production system. The research proved that the diversification in the population of mycobiota on the eggshells depended on the egg-laying hen breeding system. The microscopic fungi isolated from the eggshells included toxigenic and pathogenic species such as Fusarium culmorum and F. equiseti. As the egg storage time increased, fungi, including the pathogenic species, penetrated through the eggshells. In consequence, mycotoxins were identified in the egg whites. Type-A and type-B trichothecenes were found in the eggshell samples containing F. culmorum.

Development of a model to study Aspergillus fumigatus proliferation on the air cell membrane of in ovo injected broiler eggs

A model was developed to examine the proliferation of Aspergillus fumigatus on the air cell membrane of broiler hatching eggs and to assay the effectiveness of fungal control strategies that may be used in conjunction with late embryonic egg injection. Egg yolk was identified as the nutritive media required to sustain fungal growth. Incubation was required to predispose the egg to fungal infection by allowing the yolk to come into contact with the air cell membrane. Infertile eggs and eggs containing embryos that died before 4 d of incubation (early-dead) that had been subsequently incubated for 9 d or more were equally susceptible to fungal infection. In order to evaluate potential methods of control, these eggs were punched through the blunt end of the shell with a 16-gauge needle, placed into forced-air incubators (hatchers), and exposed to air-dispersed pure cultures of A. fumigatus. The frequency of eggs exhibiting mold growth on the air cell membrane 72 h after exposure was subjected to a Chi-square analysis model. The effect of egg position within an incubator flat in relationship to the A. fumigatus source culture, the variation between flats (levels) within a given hatcher, the variation between hatchers, and the variation between replicate trials were measured and found to be potential sources of experimental error that must be minimized in order to accept the results of an evaluation. A statistically valid model was developed that can be used to evaluate various types of fungicidal treatments of hatching eggs and their relative efficacy in association with egg injection.

Evaluation of application methods for control of Aspergillus fumigatus proliferation on the air cell membrane of in ovo injected broiler eggs

Three different techniques of applying fungicides and mold inhibitors were evaluated as control methods for Aspergillus fumigatus proliferation on the air cell membrane of eggs that were infertile or contained early dead embryos following in ovo egg injection. A controlled Aspergillus challenge model was utilized that simulates the natural occurrence of fungal growth following in ovo egg injection. Methods of application examined were egg shell spray, direct air cell application prior to Aspergillus challenge, and micro-aerosol fogging in the incubation compartment during Aspergillus challenge. Fungicides and mold inhibitors used included propionic acid, propionic acid plus ammonia, phenol, quaternary ammonium plus organic tin, hydrogen peroxide, enilconazole, and an aromatase inhibitor. When applied as egg shell spray treatments or micro-aerosol fog treatments, none of the products that were tested significantly reduced the incidence of mold proliferation on the air cell membrane when compared with untreated, but otherwise challenged, controls. When applied directly to the air cell membrane prior to fungal challenge, only enilconazole and the aromatase inhibitor significantly reduced the incidence of fungal proliferation when compared with appropriate controls.