Organic egg production. II: The quality of organic eggs is influenced by hen genotype, diet and forage material analyzed by physical parameters, functional properties and sensory evaluation

The purpose of the study was to determine, how the dietary nutrients available in organic egg production, and especially how the obligatory forage material in relation to two different hen genotypes affects the quality of organic eggs evaluated by physical, functional and sensory properties. The experimental treatments were subjected to a total of 1200 hens, which were of two hen genotypes, representing a high egg yielding hybrid; Lohmann Silver (LS), and a dual-purpose hen genotype; New Hampshire (NH). They were fed three experimental feed diets (A, B and C), which were intended to differ in protein contents, hence methionine contents. Protein content of diets A, B and C were on average 203, 199, and 182g/kg dry matter, respectively, and methionine content were on average 3.9, 3.1, and 3.0g/kg dry matter, respectively. Furthermore, two forage material treatments were supplied (maize silage+carrots and alfalfa silage), altogether distributed in a complete randomized design with 4 replicate pens each of 25 hens. Each replicate pen had a separate house and outdoor hen yard of 4m2/hen. Eight times during the experimental period, from 22 to 41 weeks of age, eggs were collected for analysis of egg weight, egg dimensions, shell strength, egg yolk colour, carotenoid content of yolk, albumen pH, albumen DM, and albumen gel textural properties. Twice during the study, boiled eggs were evaluated for sensory properties. The results showed the hen genotype significantly influenced all analyzed egg quality parameters. Furthermore, the nutrient content of the diets significantly affected the egg weight and dimension, the shell fracture force, egg yolk colour, and carotenoid content. The forage material type also affected the egg quality. Feeding the alfalfa silage resulted in eggs of higher weight, no effect on shell quality, egg yolk colours of higher darkness, redness and yellowness, and a higher content of pigmenting carotenoids, but lower content of carotenes (α- and β-). No overall sensory differences of eggs from hens fed the two forage materials appeared, although some interaction effects were seen and are discussed.In conclusion, the egg quality in organic egg production is highly affected by the hen genotype, while further influence of the diet and forage material on the egg quality depends on the specific nutrients and compositions hereof.