Comparative study of the quality and of the nutritional profile of eggs from commercial laying hens and free-ranges hens: Bibliography review.

Abstract

Eggs constitutes a very valuable food due to its content of essential nutrients such as proteins, lipoproteins, vitamins, lipids, minerals…etc. Although for some time its consumption was decrease as it was believed to be a risk factor for cardiovascular diseases, later studies found that this was not true. During the 20th century there was a boom in the use of commercial laying hens that cause a decrease in the use of native hens. Many native hens currently are at the brink of extinction, and this constitutes a problem for local farmers and for the biodiversity of hens. As the use of native hens nowadays is increasing because they are better adapted to extensive systems and the population concern of animal welfare is also increasing, studies that compare the quality of native hens to commercial hens are more common. Across the different studies selected in this bibliography review we can see that native hens are a good and viable alternative to the commercial hens. We can also see that as well as breeds have an effect in the quality of the eggs, the diet and the housing and management of the hens also have an effect on the quality of the eggs. Breed and diet also affects the nutritional profiles of the eggs. Overall, it seems that according to the bibliography consulted, commercial hens better quality as they have higher egg weight and eggshell strength, but the native hens had better nutritional profiles as they have higher fat and protein content and better lipid composition for people with some chronic diseases like diabetes. Native hens also seem to have higher content of Ca, vitamin E and some carotenoids. In order to obtain good quality eggs from native hens under free-range systems it is important to have a good diet and management.