Canadian Poultry Magazine

PIC Update: July 2011

By By Kimberly Sheppard Research Co-ordinator   

Features Layers Production Poultry Research

Uterine proteins that change with age may play a role in controlling the mineralization of eggshell

Cracked eggshells are a major factor in the loss of salable product in the egg industry, and eggshell strength is therefore a primary concern. Reducing the incidence of thin, soft shells and cracked or broken eggs is of economic benefit to producers and processors.

The eggshell is laid down in the hen’s uterus. Here, the egg spends 18 to 20 hours as calcite crystals are embedded in an extracellular matrix containing numerous proteins produced in uterine tissue. Some of these proteins help to protect the egg against pathogens and are thought to play an important role in the development of calcite crystals during shell formation. The formation of these crystals likely relates directly to the shell strength of eggs. However, not a lot of work has been done to discover how protein profiles influence crystal formation in relation to the age of the bird.

It is known that as laying hens grow older, they tend to lay eggs with thinner shells as a result of increasing egg size and a reduction of calcium reserves within the bones. Additionally, small commercial birds that lay white shelled eggs tend to have more eggshell problems than larger brown shell-egg laying birds. In addition to lack of knowledge of the influence of age and strain of bird, there is no understanding of how bird nutrition may impact the profile of uterine proteins, and potentially the structure and strength of eggshell.


Therefore, Dr. Bruce Rathgeber and his research team at the Nova Scotia Agricultural College designed a study to answer these questions. They looked at commercial (Lohmann Lite, Lohmann Brown and Shaver White) and heritage (Fayoumi and Light Sussex) breeds over a full production cycle, and fed six dietary treatments with differing levels of calcium and vitamin D3.

Egg quality traits differed between commercial and heritage breeds, and between commercial strains. There was a correlation between uterine proteins and eggshell quality traits, revealing that proteins that decreased with age were positively correlated, and proteins that increased with age were negatively correlated with all other eggshell quality traits, and vice versa for egg weight and shell weight. One particular protein was found to be potentially responsible for decrease in specific gravity and shell thickness with bird age.

The study of genetic differences in eggshell quality traits, ultrastructural variations and proteins involved in eggshell formation provide insight into the factors that cause age-related changes in eggshell quality. Overall, it was found that uterine proteins that change with age may play a role in controlling the mineralization of eggshell and growing crystals, resulting in a change in ultrastructural morphology of the eggshell and shell strength. To read more on this project, please visit


Featured Researcher
Bruce Rathgeber received his B.Sc. in agriculture from the Department of Animal and Poultry Science at the University of Saskatchewan.  He went on to work for Shaver Poultry Breeding Farms and then Cuddy Chicks before entering a M.Sc. program in the Poultry Science Department at the University of Arkansas.  He returned to the University of Saskatchewan, earning a PhD in Food Science.  Bruce became a faculty member in the Department of Plant and Animal Sciences at the Nova Scotia Agricultural College (NSAC) in 2000.  After six years in this position he joined Agriculture and Agri-Food Canada as a research scientist where he has remained located at the NSAC in Truro, N.S. His current research interests include projects that focus on the influence of production practices, bird nutrition and genetic background on product safety and quality, including both meat and eggs.  


Salmonella in the Production Chain
Featured Researcher: Dr. Michele Guerin, University of Guelph
by Kimberly Sheppard, Research Co-ordinator

Salmonella is one of the most common causes of foodborne illness worldwide. Ontario has a higher than average incidence of illness caused by Salmonella, with 40.8 per cent of total reported cases between 1997 and 2001 thought to be associated with consumption of chicken and eggs.

But how do poultry flocks become colonized with Salmonella such that it is so readily transmitted to humans at the end of the line? Where does the colonization begin? The poultry industry is in need of a greater understanding of this pathogen in order to implement effective control measures. We do know that transmission of Salmonella can occur horizontally (bird to bird via direct contact or environment), vertically (parent to progeny via eggs) or both. There are two types of vertical transmission: primary, which is infection via the ovary, and secondary, whereby the eggshell surface is infected by the cloaca, fecal material or contaminated equipment, and the bacteria penetrates into the eggs. Salmonella can enter the production chain at any level, resulting in contamination of poultry or eggs.

Because few Canadian studies have focused on temporal (time-related) distribution of Salmonella serovars in poultry breeder flocks, Dr. Michele Guerin and her research team at the University of Guelph have undertaken a temporal study of Salmonella serovars in commercial breeder flocks and hatcheries in Ontario. To gain a better understanding of prevalence, temporal trends and seasonal patterns and clusters of Salmonella, the researchers analyzed Ontario Hatchery and Supply Flock Policy data from 1998-2008, which represented all poultry breeder types.

Decreasing trends in Salmonella were observed in broiler, layer, and turkey breeder flocks, primarily due to decreasing trends in the prevalence of S. Heidelberg, although prevalence varied year by year. Long-term trends in Salmonella prevalence in the hatcheries were less consistent, and varied by year and season; the prevalence was highest in the summer and fall. S. Enteritidis (SE) was not isolated from layer and turkey breeder hatchery fluff samples. Further, it was infrequent in breeder flocks (0.9 per cent of the total isolates). However, SE was the third most common serovar in fluff from broiler hatcheries, suggesting that domestic-origin broiler-breeders might not be an important source of SE to Ontario broiler hatcheries. Clusters of S. Heidelberg, S. Typhumurium and S. Hadar in breeder flocks were temporally linked to clusters in the respective breeder hatcheries, suggesting that breeder flocks were the most probable source of these serovars to the hatcheries

It was determined that control measures be directed at the breeder flock, hatchery and sampling visit levels. For more information on this study, please visit

PIC’s Picks
By Tim Nelson, Executive Director

Oil prices are reaching record highs yet again! While it was a brief rise, we can only assume that it is a taste of things to come.

Twelve months ago PIC initiated a program of research with the University of Guelph to look at the complementary energy systems that are currently on the market. The goal was to develop a tool to assist farmers in making objective decisions about which of the various types of alternative energy systems (solar wall, geothermal, wind, digesters, etc.) is the most cost effective for their operation.

The project has been running very successfully and is now at the point where some of the assumptions made in the model need to be verified against real-life situations.

If you have had experience (good or bad) with purchasing and building an alternative energy system on farm, know the costs of running it and the savings you are (or may not be) making, we’d really appreciate hearing from you.

Please contact us by telephone at 519-837-0284 or by e-mail at, and we’ll organize a time for the project team to visit you.

Over the summer PIC is working with many producers and industry service sector personnel (huge thanks to all of you) to develop a Decision Tree for loading poultry for transport, a PAACO-certified welfare auditors course and the curriculum for our online Poultry Management course. We are also finalizing our cost-benefit of biosecurity project and Better Biosecurity video project, organization of the golf tournament (being held Sept. 7) and, of course, planning our annual Innovations Conference (being held Nov. 10 and 11, in London, Ont.).

This year we’re hosting a pre-conference workshop on farmer health and the impact your health has on your bottom line – featuring not-to-be-missed guest speaker Susan Brumby from Australia – watch this space, our website and Canadian Poultry magazine for details.

Print this page


Stories continue below