Four logistic chains with different housing systems (battery cages, furnished cages, aviary, and free-range), all housing Bovans Goldline chickens
in their mid-lay (45 wk), were compared.
In every chain, a randomised set of 1,500 eggs was sampled, and the strength was defined. At every critical point in every logistic chain, the eggs were reexamined for breakage.
The classic and furnished cage systems showed the highest percentage of breakage directly at point of lay (6.73 and 10.72%), whereas the other systems showed lower breakage (1.94% in the aviary and 1.99% in the free-range system).
Grading and packing of the eggs generated the second highest percentage of breakage (from 1.50 to 2.65%). Breakage due to transportation ranged from 0.16 to 2.65%.
There was a significant difference among the eggshell strength (shell stiffness and damping ratio) of eggs from chickens in different housing systems, showing eggs from chickens in the aviary system to be stronger than cage eggs (classic and furnished) and free-range eggs to be weaker than the other eggs.
A significant correlation was found between eggshell strength and the likelihood of breakage in the production chains.
In conclusion, it was first shown that, besides the laying, packing of the eggs is a critical point in the logistic chain of consumption eggs; second, the strength of the eggs in the different housing systems differed, and, finally, the eggshell stiffness and damping ratio of consumption eggs are an acceptable measure for rapid eggshell quality assessment and could provide a good predictive value for eggshell breakage in all types of table egg production chains.
The study is published in Poultry Science
, Volume 85, September 2006 edition.