Métodos para desinfecção de ovos férteis e caracterização de sua microbiota

Abstract

The aim of this study was to evaluate the effect of different disinfection procedures alternative to fumigation with formaldehyde on the enumeration and isolation of eggshell surface microorganisms, eggshell quality, hatching parameters, neonate chick quality and enumeration and isolation of microorganisms of the yolk sac of day-old chicks. A total of 10,080 hatching eggs were collected from a 70-wk-old commercial broiler breeder flock and distributed in a completely randomized block design with seven treatments: fumigation with paraformaldehyde (5.03g/m3/30 min; FF), fumigation with ozone (5-15ppm/30 min; FO), ultraviolet light-C irradiation (8.09 mW/cm2; 120 s; UV-C), hydrogen peroxide spraying (3%; 0.69 mL/egg; H2O2), peracetic acid spraying (0.3%; 0.69mL/egg; PAA), water spraying (0.69mL/egg; water control - WC), and without disinfection (dry control - DC). Eight samples (pool of four eggs each one) from each treatment were collected to enumerate the presence of Enterobacteriaceae, total aerobic microorganisms, and mold and yeasts on the eggshell after the disinfection procedure. A total of 28 eggs per group were collected to evaluate the eggshell strength and thickness. A total of 924 eggs per treatment were placed in twelve 77-egg trays to evaluate eggs weight loss during incubation, hatchability, hatchability of fertile eggs, embryo mortality (initial, middle, and late), chick weight and percentage of saleable chicks at hatching. The counts of Enterobacteriaceae and total aerobic microorganisms present in the yolk sac were performed in thirteen day-old chicks originated from each treatment. Culture-dependent methodology was carried out for enumeration and isolation of the microorganisms on eggshell surface and yolk sac in one-day-old chicks, followed by identification by mass spectrometry (MALDI-TOF). Spraying eggs with PAA and UV-C significantly reduced aerobic microorganisms plate counts compared to the DC group. In addition, eggs disinfected with PAA had lower Enterobacteriaceae counts than those from DC and WC groups. Eggshell quality, incubation parameters, chick quality, and microbiological counts for yolk sac did not differ (p>0.05) among treatments. The Proteobacteria phylum was dominant either on eggshell surface or in the yolk sac. Nineteen genera of bacteria were identified on eggshell surface and the genus Staphylococcus (18%) had the highest relative frequency. In the yolk sac, 12 genera of bacteria were identified and the bacterium of the genus Escherichia (32.6%) had the highest relative frequency. This study demonstrated the potential for the application of PAA and UV-C for eggshell disinfection.