The future of the U.S. egg industry is uncertain; will conventional cages continue to be the industry standard, or will enriched colonies or cage-free become the predominant husbandry systems? Whether the future is cage-free or in some type of cage, layer genetics companies say that today’s high-performing egg laying strains will be able to adapt.

“Successful animals in domestication are successful because they can adapt to environments that humans provide,” said Neil O’Sullivan, research director, Hy-line International. All common domesticated species—like dogs, horses and chickens—are successful because they have highly adaptive natures. While selecting their genetic lines of birds for a number of efficiency, production and quality traits, breeders have also selected for birds that perform well in group environments and in a number of different housing situations.

Sire testing  

Frans van Sambeek, director of research and development, Institut de Sélection Animale at Hendrix Genetics Company, said that breeding programs were changed years ago to reflect the varied environments in which commercial layers were housed because the housing changes that have already taken place in Europe (and may take place soon in the U.S.) were anticipated decades ago. Both Institut de Sélection Animale and Hy-line conduct sire progeny testing on commercial crosses of hens in conventional cages and enriched enclosures on contractor farms under real-world field conditions. The hens are individually wing banded at hatch and are housed in the enclosures in groups of 5-12, with all of the hens within an enclosure having the same sire. This is done to ensure that there are enough replicate enclosures per sire for accurate breeding value estimation.

In addition to gathering data on important production parameters like egg production and quality, behavioral data is also gathered from the sire testing enclosures. Temperament scoring is an example of one form of behavioral data that is gathered during the sire testing. O’Sullivan said that temperament scoring is a means of measuring how reactive the hens are to a novel stimulus, such as someone arriving in the house wearing a different color of coveralls than is used by the regular caretakers. He said that breeding companies have been conducting a form of temperament scoring for decades.

Other behavioral tests consist of measuring the flight distance and social attraction that hens exhibit to people they are used to seeing every day. O’Sullivan said that birds can be very reactive to strange humans but still have perfect feather coverage because they normally don’t see anyone strange. Being “good” on one behavioral trait doesn’t necessarily mean that hens will be “good” on another trait, according to O’Sullivan. That is why breeders measure a number of different traits to have a balanced selection program. “It is a balanced selection program that producers will respond to over the long term,” he said.

Genetics companies use many replicates of sire progeny groups on different farms in different types of housing. This is important because some families will have very similar responses in different environments, but others will have varied responses. “Livability is the most responsive trait, followed by egg production, which is followed by temperament scoring. Long-term selection using information from group environments with same sire relatives (progeny, half-siblings and relatives’ data from previous generations) is very valuable in informing selection choices,” said O’Sullivan.

Can’t we all just get along?  

Aggressive behavior traits are considered to be “optimal traits,” according to van Sambeek, but too much aggressive behavior can cause problems in just about every type of housing system. “You don’t want the birds that are pecking all the time, and you don’t want birds that are being pecked all the time,” he said.

“An aggressive individual in the group will attempt to get first rights to resources like feed or water in the enclosure, and this leads to an increased level of social turmoil, which leads to social stress,” said O’Sullivan. “The social stress creates a destructive cycle where the submissive birds will have increased levels of corticosterone.” Under the long-term effects of excessive levels of corticosterone, the submissive birds will act out aggressively to the dominant bird, often during or just after she has laid an egg and the cloaca is still everted. “Most people think that it is the dominant bird that creates most of the damage, but it is often the submissive birds that ultimately go after the dominant birds,” he continued. This model of behavior is also seen in some mammals.

To help root out overly aggressive birds, Institut de Sélection Animale has a long-running program of housing large groups of non-beak trimmed birds together in environments with high light intensity. Data gathered under these conditions in challenge studies is used to inform selection decisions in pedigree lines and could be an important step towards a future where routine beak trimming of hens is no longer necessary.


Measuring behavioral traits is an important part of any selection program, but the bottom line is still overall flock productivity and efficiency. “We evaluate all the lines and strains in a variety of housing systems to ensure that they all perform well,” said van Sambeek. “The number one goal is still to produce the maximum number of high quality eggs for the lowest cost. The goal is a hen that lays 500 eggs during one laying cycle.”

Feathers and efficiency  

Hens housed in enriched environments get more exercise than hens housed in conventional cages, and locomotion requires calories, but housing birds in enriched cages could still lead to better feed conversion, according to O’Sullivan. He said that birds in enriched cages have better feather coverage than those housed in conventional cages, and that better feather coverage leads to less heat loss and less feed energy used to maintain body temperature.

Better feather coverage in enriched enclosures when compared to conventional cages likely results more from increased preening behavior in the enriched enclosures than it does from a reduction in feather pecking. “Because we have been selecting so long in the group environment, we have dramatically reduced the incidences of feather pecking and cannibalism,” O’Sullivan said.

Chicken of the future  

In Institut de Sélection Animale’s chicken of the future project, non-beak trimmed pure-line pedigree birds are housed in floor pens with trap nests to collect the eggs. Egg production, feathering, laying behavior and nesting behavior are measured on an individual bird basis. If a hen is overly aggressive, then this information will be used to inform the selection decisions involving relatives of this bird.

All of Institut de Sélection Animale’s commercial crosses on the parent and grand parent levels are housed in barn systems. “So we know on a line level what the behavior is of these birds in barns with either floor or aviary systems,” van Sambeek said.

Must maintain use of cages  

Breeders have been interested in putting birds in individual cages for decades because it facilitated data collection on an individual basis and allowed for known parentage of progeny based on artificial insemination. O’Sullivan said that the ability to house birds individually in cages will continue to be important for breeders, and that any bird welfare legislation will have to allow for this.

Presently, layer genetics firms house pedigree line birds in individual cages in clean environments with filtered air.