That phenomenon of 'reproductive attitude' is a headache for producers who must figure out how to deal with less productive hens that "partition" nutrients needed for egg production into their own bodies. "They like to be a little bit more selfish with their nutrients, and continue growing," said Dr. Martin Zuidhof, an Alberta Agriculture researcher who is collaborating with the University of Alberta to solve the dilemma.
"Some of the broiler breeders (parents of chickens raised for meat) are happy to shift their nutrients from the growth of their bodies to egg production, but some of them don't do it very willingly. It is not a conscious thing the bird does, but it does express a tendency of that bird to either be generous or to be selfish with its nutrients."
Channelling food into body-building results in lower egg production, chick production and chick quality, said Dr. Frank Robinson, professor of Agricultural Food and Nutritional Science at the University of Alberta.
The University of Alberta study of 300 high-performance broiler breeder hens explores the relationship between the hen's growth and reproductive performance, to improve our understanding of how producers can better manage the birds' body weight during puberty, and also during the egg-laying period that comes later.
No other broiler breeders research program works as closely with individual birds. The research team has shown the importance of recognizing that large poultry populations are made up of a collection of individuals--each with their own way of balancing their growth and reproductive priorities. "Building definitions of 'reproductive attitudes' has been an eye-opening process that challenges basic assumptions about how these birds function," said Dr. Rob Renema, a resea rcher in the Department of Agricultural Food and Nutritional Science at the University of Alberta.
Individual assessments have identified a small number of 'super-hens' that have an incredible growth potential and are also capable of producing many more chicks than usual. The more typical pattern is for the hen to lose some body weight to support egg production. "The trouble with this is that these 'martyr birds' may eventually suffer from burnout when they don't balance their own needs well enough," Dr. Renema said.
Discovery of the exceptional "super-mom" birds that don't fit the textbook norm has opened new doors in the research program. "If the offspring of these special hens are also more efficient, the broiler industry could move forward in leaps and bounds.
As a result of their findings, Robinson, Renema and Zuidhof have broadened their research focus to include exploration of links between hen reproductive attitude and broiler quality. Their work will contribute to the production of high-quality broilers and to the growing research focus on development of high-quality, value-added poultry products.