Dr. Kenneth Anderson, Department of Poultry Science, NCSU, presented results from brown-strain hens reared and housed in cages compared to range. In the case of the non-confined pullets, rearing through 12 weeks was completed in litter pens followed by movement to a range.
Performance was monitored from 17 weeks to 82 weeks of age. Pullets reared in cages were 93 grams heavier than pullets reared on range.
There was a 13% reduction in feed consumed by range pullets consistent with body weight and supplementation from foliage.
90% vs. 86%
Caged hens showed significantly higher feed conversion efficiency and egg mass. Mortality and egg production on a hen-housed basis were also significantly different.
There was no significant difference in egg weight or size. Caged hens produced 90% grade A compared to 86% for the range hens although there was no difference in the number of checks between the housing systems.
Fat levels varied
There were no differences in cholesterol content of eggs and both vitamin A and E levels were similar. Eggs from the range-housed hens had higher total fat and correspondingly both monounsaturated fat and polyunsaturated fat levels compared to caged hens.
There was a numerical but nutritionally insignificant difference in omega-3 content of eggs -- 0.13%.
As expected beta-carotene levels were higher in the range-housed hens compared to the caged hens although this difference could be compensated for by supplementation with the commercially available xanthopyll supplements.
Immune responses differed
An interesting observation was that the immune response of the range-housed hens was lower than their counterparts in cages. This was determined by the antibody tier following Newcastle disease vaccination.
Stress associated with free-range housing is in all probability responsible for the difference in immune function favoring cage housing.