Quality of eggs of hybrid and Italian hens reared under an organic production system.

A trial was carried out to compare the quality of eggs from two hybrid strains (Hy-Line Brown, HLB and Hy-Line White, HLW) and two Italian breeds (Ermellinata di Rovigo, ER and Robusta maculata, RM) of hens reared under an organic production system, from July to December in Northern Italy. Hen-day egg production was higher (P<0.01) in hybrid strains when compared to ER and RM. Aging (from 30 to 42 weeks of age) of animals significantly affected the egg weight, the eggshell thickness and the eggshell weight according to genotype and variations in environmental conditions. The HLB hens did not show any variation in eggshell thickness, but a constant decrease in eggshell percentage from 34 weeks of age. From 34 to 42 weeks of age significant (P<0.01) variations affected the ash content of hybrid yolks according to genotype, and the n-6/n-3 ratio of yolk lipids in all groups. At 44 weeks of age the HLW femurs and tibiae showed stress and modulus of elasticity higher (P<0.01) than the other genotypes.