Canadian Poultry Magazine

PIC Update: December 2008

By PIC   

Features Business & Policy Consumer Issues

Breeder Aggression and Social Behaviour

Broilers grow faster today than ever before, with increased feed
conversion efficiency and increased meat yield. Although genetic
selection based on production traits has produced an efficient meat
bird, egg production and fertility traits are increasingly difficult to

Alberta researchers are studying the relationship between female feather coverage and
reproductive condition with male mating aggression and social behaviour 


University of Alberta researchers have investigated whether poor feather cover is related to high mating frequency, and if a correlation between male or female body weight and aggression or mating behaviour exists.



Broilers grow faster today than ever before, with increased feed conversion efficiency and increased meat yield. Although genetic selection based on production traits has produced an efficient meat bird, egg production and fertility traits are increasingly difficult to maintain.

Recent research has suggested that there has been an increase in aggressive male behaviour in broiler breeder stocks – at times severe enough to result in hen injury or death. Any aggressive encounter that causes injury or stress is a welfare concern, and stress related to repeated aggressive interactions can cause a corresponding decrease in production. Knowing which factors play into aggressive interactions would provide the industry with new management options toward reducing or eliminating these aggressive interactions, thereby improving both
production and hen welfare.

At the end of a production cycle some breeder hens have very poor feather cover while others have excellent cover. Poor feather cover is costly to the hens and to the producer as it means poor energy utilization and eventually decreased egg production. It is not known if the poor feather cover is due to high mating frequencies, age, normal wear, or aggressive feather pecking. Although high mating frequencies results in higher fertility levels, aggressive encounters may lead to more hens avoiding males and spending time on the slatted areas.

Dr. Rob Renema, together with Erica Holm, and Drs. Frank Robinson and Martin Zuidhof at the University of Alberta have been investigating whether poor feather cover is related to high mating frequency, and if there is a correlation between male or female body weight and
aggressive or mating behaviour. They are also interested in the relationship
between feather cover and reproductive morphology.

Their findings? Feather cover was found to be a general indicator of mating frequency. Hens played a greater role in reproductive behaviour than expected, with females accepting, avoiding and seeking out males. Results from a concurrent breeder farm trial suggests that an important component of female sexual behaviour may be based on when they mature relative to the males, with earlier-maturing hens being more receptive to males throughout lay. It was confirmed that higher incidence of aggressive behaviour leads to increased frequency of hens on the slatted areas.

It was also found that having large males close in weight can lead to increased mating, forced mating, and aggressive behaviour. However, when one dominant male is present, there is less aggression toward the hens than when multiple males are vying for control in a pen. It is suggested that changes to the number of males within a high weight range could help to lower male-to-female aggressive encounters. Behaviourally, having males close in weight may not be an advantage, although this needs to be confirmed in larger group sizes. To read more on this study, please visit


Dr. Robert Renema is an assistant professor of Value-Added Poultry Science and part of the Poultry Research Centre. His research interests over the past 17 years have focussed on the optimization of growth and reproductive processes in commercial poultry, and connections between maternal and offspring yield and efficiency traits. His research area has expanded to include work with the production of value-added egg and poultry products. By exploring the
biology of growth as it relates to nutrient uptake and transfer into muscle or eggs, he hopes to improve the efficiency of poultry product enrichment.

Born in Victoria to Dutch immigrant parents, he eventually settled in Edmonton, where he married Stephanie, a girl with similar roots. Their three kids, although genetically Dutch, don’t speak a word of it – although they’re pretty good at describing how chickens work.

A time for leadership
It was a good conference – a lot of people, many more than we expected but we packed them all in, fed them all and imparted a lot of knowledge and had a few laughs along the way. I could write about the talks and the presenters but they’re all featured on the PIC
website and if anyone wants any of them we’ll be happy to fax and or e-mail them to you.

Dr. Donald McQueen Shaver told attendees of Poultry Industry Council’s Innovation Conference that what is needed today is “Churchillian Leadership.”


I wanted to mention something else in PIC’s Picks this month and that was the troubling overtones on the state of the world and the understated but very real call for leadership. It’s not news that we’re in a financial downturn and some aspects of this are particularly worrisome for poultry producers, particularly future feed availability and/or cost as suggested by Steve Leeson. But more generally Dr. Donald Shaver called for the need for some ‘Churchillian’ style leadership, Derek Burleton said that TD numbers hadn’t shown any rationale for the roller coaster ride the stock market was taking rather blaming flightiness and nervousness
of the brokers. (Not dissimilar to sheep in many ways – he didn’t use those words exactly – he’s not a farmer) and Mike Dungate made it clear that the impending call to Ministers to renew WTO talks in December is not about achieving a common goal on world trade (one would imagine almost an impossibility with regime change about to occur in the US) but more about ensuring the longevity of tenure of the current regime at WTO. What is going on in the world? Why has the culture of personality taken over from that square chinned quietly spoken hero, the quiet achiever with the conservative, so probably not popular, but sensible ideas?

It’s not as if those heroes don’t exist, we have a plethora of them in agriculture, farmers who simply get on with the business of producing and marketing wholesome food. And we had quite a few at the Poultry Conference talking quietly and passionately about their work and making suggestions about what we might do to mitigate the impact of the impending recession, about saving energy, being smarter in designing barn ventilation, feeding more specifically to cost, and about where we should invest research funds to make the world a healthier, more sustainable place to live and a safer place to eat. Was anyone outside of Bingemans hearing their message?

John Wilkinson,  Minister of Research and Innovation, opened the PIC innovation conference.


We hear a lot about the dearth of leaders in farming and agriculture. There’s no shortage of leaders – they’re there alright, but they’re not tall

poppies so we don’t see them. They’re smart sensible people with good ideas for the future of our agricultural industries who won’t stand tall because we’re too eager to shoot them down just as soon as they get up.

The challenge for industry is to develop mechanisms that will allow these quiet achievers to be noticed and their collective opinions and ideas heard, understood and acted upon so that when we leave the Innovation Conference in future years we’re not only enriched by new ideas, we’re  also excited by the blueprint for the future being described by our peers.

High Pressure Processing of Poultry Products

Mansel Griffiths, University of Guelph

Avian pathogenic E. coli (APEC) are common in barn dust. Following inhalation by chickens, the bacteria are often eliminated by the clearance mechanisms of the respiratory system. However, in the presence of other immune challenges caused by viruses, Mycoplasma, ammonia, or dust, APEC can establish in the respiratory system and disseminate throughout the body. This results in respiratory/septicemic disease.  This diseaae occurs commonly in two- to four-week-old broilers and is a leading cause of economic loss. A vaccine against APEC would provide industry with a tool to manage this problem, improving both animal health and profitability.

Dr. Carlton Gyles and graduate student Haitham Ghunaim at the University of Guelph have been investigating four different antigens for their ability to induce protection in broilers against E. coli respiratory/septicemic disease. The researchers injected the antigens into broilers and collected serum containing the antibodies produced in response. When the antibodies were injected into broiler chickens it was found that antibodies against three of the four antigens tested protected the birds from APEC respiratory challenge. They then tested the three successful antigens further by two methods: i) vaccinating broiler breeders and assessing their chicks for protection after challenge with APEC, and ii) vaccinating broiler chicks and later challenging them with APEC.

Their findings?  Vaccinating the broilers breeders did not lead to a protective effect for their chicks in this study. For the directly vaccinated chicks, one antigen (PapG) was effective in eliciting protective antibodies against E. coli. This finding indicates that PapG is a promising vaccine candidate for a vaccine against respiratory/septicemic disease due to E. coli in broilers.

To read more on this study, please visit our website at

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