Inactivation of Salmonella and avian pathogens on hatchery eggs using gas phase hydroxyl-radical process vs formaldehyde fumigation: Efficacy, hatching performance and grow-out of Chickens

Hatcheries have been identified as a significant source of Salmonella within poultry production. Consequently, there is a need for effective egg disinfection methods that can reduce the pathogen burden while preserving the egg integrity and embryo. The metrics for a successful egg disinfection method are typically a reduction in Total Aerobic Count (TAC) while retaining hatching rates. In this study, a gas phase hydroxyl-radical process was validated and verified as a hatchery egg disinfection method. The process is based on applying a hydrogen peroxide mist in combination with ozone gas and UV-C to generate antimicrobial hydroxyl radicals. The treatment (2 % hydrogen peroxide, 20 ppm ozone and 19 mJ/cm2 UV-C; designated as HR) for inactivating Salmonella (serotypes Enteritidis and Typhimurium) inoculated onto eggs could eliminate the pathogen (>5 log CFU/egg reduction) but left residual TAC (1.53 log CFU/egg reduction). Surface sterilization was achieved by a pre-treatment of eggs with the photo-catalyst riboflavin (13.75 mM) followed by 3 % hydrogen peroxide delivered at 70 °C prior to the hydroxyl-radical treatment (3 % hydrogen peroxide, 20 ppm ozone and 114 mJ/cm2 designated HRS). The surface sterilization of eggs coincided with the removal of the cuticle layer with the HRS treatment but not HR. The cuticle layer was also compromised by formaldehyde treatment. When the different treatments were applied to fertile hatchery eggs (n=50 eggs per treatment group), there was no significant difference in hatchery rate (64-74 %), with hatch to fertility being higher for disinfected eggs (89-97 %) compared to the non-treated control (80 %). The seven-day mortality (0 - 2 birds) and feed conversion ratio (1.59 - 1.75 kg/kg feed) did not significantly differ between the treated vs controls. The HR treatment could eliminate Enterococcus faecium, Escherichia coli (>5 log CFU/egg reduction) although HRS was required to inactivate Pseudomonas aeruginosa (>5 log CFU/egg reduction) and reduce Aspergillus niger spores (3.08±2.25 log CFU reduction). The study has provided treatment options for hatchery egg disinfection and alternative to formaldehyde treatment.

Fumigating broiler hatching eggs with lysozyme product (Inovapure) to reduce eggshell microbial load

Experiments were conducted to evaluate the effectiveness of a lysozyme product (InovapureTM) (LP) against E. coli penetrating eggshells. In the first microbiological experiment, 60 agar-filled eggs were inoculated with E. coli suspension, then fumigated with distilled water, 1.5% or 3.0% LP or a quaternary ammonium product (QA) at 0.125% for 10 min. In the second microbiological experiment, another 60 agar-filled eggs were fumigated with the same sanitizer treatments first, then inoculated with the E. coli suspension. Eggshells were candled and visual colonies were counted after 48 h incubation. An animal experiment was conducted to evaluate LP applied to the surface of 2080 broiler hatching eggs on hatching and growth performance. Hatching eggs were submerged in an E. coli suspension. After drip drying, eggs were randomly divided into four fumigation treatments, each with four subsets of 150 eggs. Fumigation treatments were the same as in the microbiological experiments. Eggs were incubated in 8 incubators (2 replicate incubators per treatment) and the broilers were grown to 33 d of age. In the microbiological experiments, inoculated eggs fumigated with 3.0% LP and 0.125% QA reduced (P < 0.05) the total amount of E. coli to 11 cfu/egg and 10 cfu/egg, respectively. When eggs were sanitized prior to inoculation, 3.0% LP demonstrated (P < 0.05) ongoing bactericidal action to prevent E. coli penetration. No differences in hatchability, fertility rate or egg weight loss percent were found among sanitation treatments. At hatch, body weight or the ratio of yolk sac weight to yolk-free body weight were not affected by the sanitation treatments. However, the application of sanitizers decreased (P < 0.05) the presence of E. coli in the yolk sac of newly hatched chicks. Feed consumption, body weight and feed conversion ratio were not affected by sanitation treatments. However, average daily body weight gain was lower (P < 0.05) following QA. Overall, 3.0% LP demonstrated acceptable activity against E. coli on eggshells, and provided ongoing bactericidal action to prevent E. coli penetration without negatively affecting growth performance.

Recovery of Salmonella serovar Enteritidis from inoculated broiler hatching eggs using shell rinse and shell crush sampling methods

This study compared the recovery of Salmonella from hatching eggs using 3 sampling methods (eggshell rinsing, eggshell crush following a previous rinse, and eggshell crush without previous rinse). Eggshells were drop-inoculated with approximately 10(1), 10(2), or 10(3) cfu/eggshell of Salmonella Enteritidis and allowed to dry at room temperature for 1 or 24 h. For the shell rinse groups, each inoculated egg was rinsed with buffered peptone water. These rinsed eggs were used for the shell crush with previous rinse groups, and each egg was aseptically cracked, the contents discarded, and the eggshell and membranes crushed with buffered peptone water. This same crush procedure was used for the shell crush without previous shell rinse eggs. The recovery of Salmonella 1 h after inoculation for shell rinse sampled eggs was 16% positive at 10(1), 49% at 10(2), and 93% at 10(3) cfu/eggshell challenge. For the shell crush with previous shell rinse, sampled egg recovery was 0% positive at 10(1), 3% at 10(2), and 17% at 10(3) cfu/eggshell. For the shell crush, sampled eggs had recovery of 23% positive at 10(1), 69% at 10(2), and 96% at 10(3) cfu/eggshell challenge. The recovery of Salmonella 24 h after inoculation for the shell rinse eggs was 3% positive at 10(1), 12% at 10(2), and 22% at 10(3) cfu/eggshell challenge; recovery for shell crush with previous shell rinse sampling was 2% positive at 10(1), 8% at 10(2), and 5% at 10(3) cfu/eggshell challenge; and for the shell crush sampling recovery was 2% at 10(1), 32% at 10(2), and 42% at 10(3) cfu/eggshell challenge. Eggshell crush was a more sensitive (∼10 percentage points) sampling method than eggshell rinse at both 1 and 24 h, but both methods were equally optimal when the inoculum was at 10(3) and samples were collected after 1 h. Waiting 24 h after inoculation to sample significantly lowered the recovery for both the shell rinse and shell crush sampling methods by ∼40 percentage points.