A significant nutritional advantage of eggs produced by chickens housed on range versus in cages could not be established, according to a recent study published in the July 2011 issue of Poultry Science. However, the cholesterol levels in all eggs were found to be lower than U.S. Department of Agriculture guidelines, prompting the USDA to review and revise downward its estimates for average cholesterol levels in eggs.
Data for the study was collected in 2008 and 2009 by Dr. Kenneth E. Anderson, a professor in the Department of Poultry Science at North Carolina State University.
“The key takeaway from this research is that an egg, no matter where it’s produced, is a very nutritious product," said Anderson. "Eggs from a range production environment did have higher levels of total fat than eggs produced by caged hens, but they did not have higher levels of cholesterol. Perhaps the most striking finding was that both cage- and range-produced eggs actually have lower cholesterol levels than previously believed, which has led the USDA to lower the cholesterol guidelines for eggs in the USDA Nutrient Database for shell eggs to 185 mg per egg, down from 213 mg."
Egg samples were collected at 50, 62 and 74 weeks of age during the productive life of the flock and sent to four different laboratories commonly used for egg nutrient analysis. The results showed no influence of housing environment (range or cage) on egg levels of vitamin A or vitamin E. However, beta-carotene levels were higher in the range eggs which, according to Anderson, may have contributed to the darker colored yolks observed in these eggs during the study. The study also found no difference in cholesterol content between range- and cage-produced eggs.