Comparison of egg quality between the Canarian free-range Hen and the commercial Hen

Abstract

This work has been performed based on the interest shown for a long time by the “Asociación `La Campera´ para la Recuperación de La Gallina Campera Canaria”, in order to study and promote the Canarian free-range hen with the collaboration of the ULPGC Therefore, this project is focused on the evaluation of the eggs´ quality, with the general objective of determining differences between the commercial hens and the Canarian free-range hens, under similar production conditions. In regard to the aforementioned, two studies have been carried out: 1) Study 1, where the egg quality of two commercial hens´ breeds, Isa Brown and Leghorn, have been analysed. That is to say 40 eggs were analysed, 20 of each breed. 2) Study 2, which has been based on comparing the quality of the Canarian free- range hen´s eggs with the quality of the commercial hen´s eggs. To obtain this, not only data collected in the study 1 (40 commercial hen´s eggs) has been used, but also data of a previous work (Ball, 2019) has been obtained (80 Canarian free-range hen´s eggs and 10 commercial hen´s eggs). Measurement of the following parameters have been carried out on the eggs: the egg´s weight, the flotation test, the ovoscopy, the air chamber measurement, the egg´s maximum width and length, the shell´s thickness, the dense white´s diameter and height, the yolk´s diameter and height, the total, yolk and white´s pH, the yolk´s colour, the Haugh Units, the yolk´s index, the dense white´s index and finally the shape´s index. In addition, Chi-square test (χ 2 ) or Fisher´s exact test and Wilcoxon´s test for independent data were used for data analysis. For study 1, the results showed a better commercial quality (in terms of shape and pH) in Leghorn breed´s eggs. On the other hand, study 2 detected a good structural quality of free-range hen´s eggs, which showed greater weight and length and adequate shell thickness, although a larger air chamber in commercial hen´s eggs. Regarding the quality of freshness, the results of the indexes (dense white´s index, yolk´s index and UH), and the yolk pH and white pH, indicated a significant advantage for the commercial hen´s eggs. Because all the eggs in this study had a similar life time, the differences found lead to the need to consider other different reference values, such as standards for determining the category of free-range hen´s eggs with reference to those officially considered for the commercial egg.