Egg Cleanliness

Microbiological impact of three commercial laying hen housing systems

D.R. Jones, et al. 
Poultry Science (2014) Vol. 94, Iss. 3: 544-551

Key Learnings:

  1. Eggs safety is enhanced when alternative housing systems use nest boxes [with nest pads];
  2. Less contamination on egg shells laid on nest pads than those laid on bare wire
Read the Abstract

Microbiological impact of three commercial laying hen housing systems
D.R. Jones, et al., Poultry Science (2014) Vol. 94, Iss. 3: 544-551

Abstract 

Hen housing for commercial egg production continues to be a societal and regulatory concern. Controlled studies have examined various aspects of egg safety, but a comprehensive assessment of commercial hen housing systems in the US has not been conducted. The current study is part of a holistic, multidisciplinary comparison of the diverse aspects of commercial conventional cage, enriched colony cage, and cage-free aviary housing systems and focuses on environmental and egg microbiology. Environmental swabs and eggshell pools were collected from all housing systems during 4 production periods. Total aerobes and coliforms were enumerated, and the prevalence of Salmonella and Campylobacter spp. was determined. Environmental aerobic and coliform counts were highest for aviary drag swabs (7.5 and 4.0 log cfu/mL, respectively) and enriched colony cage scratch pad swabs (6.8 and 3.8 log cfu/mL, respectively). Aviary floor and system wire shell pools had the greatest levels of aerobic contamination for all eggshell pools (4.9 and 4.1 log cfu/mL, respectively). Hens from all housing systems were shedding Salmonella spp. (89–100% of manure belt scraper blade swabs). The dry belt litter removal processes for all housing systems appear to affect Campylobacter spp. detection (0–41% of manure belt scraper blade swabs) considering detection of Campylobacter spp. was much higher for other environmental samples.

Aviary forage area drag swabs were 100% contaminated with Campylobacter spp., whereas enriched colony cage scratch pads had a 93% positive rate. There were no differences in pathogen detection in the shell pools from the 3 housing systems. Results indicate egg safety is enhanced when hens in alternative housing systems use nest boxes. Additionally, current outcomes indicate the use of scratch pads in hen housing systems needs to be more thoroughly investigated for effects on hen health and egg safety.

Click here to download the abstract and full research document
(the publisher may have fees for the full reports)

Salmonella penetration of egg shells and proliferation in broiler hatching eggs–a review

N.A. Cox, et al. 
Poultry Science (2000) Vol. 79, Iss. 11: 1571-1574 

Key Learnings:

  1. The presence of salmonellae in the nest box, farm cold room, hatchery truck, or hatchery environment may lead to contaminated eggs;
  2. Eggs contaminated in this way can carry salmonellae on the shells or beneath the surface of the shells.
  3. The hen brings soil and feces into the nest, and these materials have been shown to contain microorganisms, including salmonellae.
  4. Eggs laid in wet, dirty nests or on the floor are more likely to be contaminated
Read the Abstract

Salmonella penetration of egg shells and proliferation in broiler hatching eggs–a review 

Abstract 

The presence of salmonellae in fertile broiler hatching eggs has been clearly identified as a critical control point in the salmonellae contamination of broiler chickens. This paper reviews the published research studies on a) the penetration and proliferation of salmonellae in hatching eggs, b) the consequences of this contamination on the contamination of the final product, and c) the egg’s defenses against invading salmonellae. A better understanding of the material in this review paper will assist poultry researchers and the poultry industry in continuing to make progress in reducing and eliminating salmonellae from fertile hatching eggs, hatcheries, and breeder flocks.

Click here to download the abstract and full research document
(the publisher may have fees for the full reports)

Bacterial Penetration of the Eggshell and Shell Membranes of the Chicken Hatching Egg: A Review

M.E. Berrang 
J Appl Poult Res (1999) Vol. 8, Iss. 4: 499-504 

Key Learnings:

  1. The natural defenses of the egg are not entirely adequate to prevent penetration and survival of salmonellae.
  2. Likelihood of penetration can be lessened by avoiding contact between the egg and contaminated surfaces or substances such as feces or dirty nest pads.
Read the Abstract

Bacteria Penetration of the Eggshell and Shell Membranes of the Chicken Hatching Egg: A Review
M. E. Berrang1, N. A. Cox, J. F. Frank and R. J. Buhr

Abstract 

Bacteria, including human enteropathogens, can penetrate the outer structures of the egg. There are several mechanisms employed by bacteria to gain entry to the egg. The most likely area on the egg to be penetrated is the air cell end, especially when temperature differential and moisture are favorable. The natural defenses that an egg has against such attack are generally not adequate to completely protect the egg from bacteria. The implications and consequences of bacterial penetration of the shell and membranes are serious, including potential dissemination of human pathogens to the hatchery, grow-out flock, and final product. This paper reviews the mechanisms involved in bacterial penetration, methods used to detect penetration, and the stages of modern production which lend themselves to shell penetration and the subsequent potential contamination of many chicks.

Click here to download the abstract and full research document
(the publisher may have fees for the full reports)