The University of Manitoba's Faculty of Agricultural and Food Sciences has been evaluating the Hellmann cage, one of several enriched cages for housing laying hens.

A conventional cage usually houses four to six birds and provides 72 to 73 square inches per bird.

The cage being evaluated houses 24 to 26 birds and provides almost 100 square inches and such amenities as a scratch pad and perching and nesting areas.

Animal Science Professor Emeritus Dr. Bill Guenter says egg production, feed consumption, behavior, body weight, feather condition and biological factors that indicate stress were measured over a 40-week production cycle.

Dr Bill Guenter-University of Manitoba

The only significant difference we found between these cages was better bone density, better bone structure in the hens that were in the enriched cage.

That's probably because they had more space to exercise and they used the perches which helps to also strengthen bone.

So it indicates that the birds are probably in a better physical condition and therefore less chance of breakage and pain being imposed on them.

If you have six birds in a small cage that has 73 square inches if five of them crowd into one area there's still very little space left for that one extra bird but if you've got 24 birds in one cage at 100 square inches and they concentrate in one area, for instance by the scratch pad or something, there might be five or six birds that have 250 inches space because they're able to roam around more.

Dr Guenter says, even though the space allocation per bird overall isn't that much greater, the individual bird can get periods of time where they have way more space.