Egg Industry Center

Research Library

Research files are added periodically on a range of topics found in this library. Library resources consist of old and new research related to the egg production and processing industry.

Egg Quality


The impact of hen housing on egg production performance and egg quality was studied by the Coalition for Sustainable Egg Supply (CSES) study which analyzed eggs for shell strength, shell thickness, Haugh unit, vitelline membrane properties and egg solids. 24 eggs were randomly selected and assessed from each housing system. Diets were specifically formulated for conventional cage, aviary and enriched colony systems based on hen productivity and feed ingredients available while being cost efficient. Dietary changes were found to have the most impact on shell parameters, vitelline membrane parameters and egg total solids contrary to the laying hen housing system. Specific dietary changes and results for each element may be found in the article. Further research needs to be conducted in controlled research settings to determine any affect on housing systems on egg quality.

Split feeding was tested as a strategy to improve shell quality in laying hens. The experiment was conducted in brown laying hens from 39 – 85 weeks of age, changing the diet in three phases to coincide with the hens’ age. Both diets had the same amount of fine and coarse limestone available in a 30:70 ratio. The split feeding style diet fed 30% of limestone in the morning and 70% of limestone in the afternoon, while the conventional feeding style fed the same diet in the morning and afternoon. 120 eggs were collected per feeding system and assessed. Bone strength was also measured. The results concluded that split feeding did not improve performance or shell quality; however, this might be due to flock health problems incurred during the study.

The mineral content of whole dried eggs was reviewed with respect to the influence of factors other than hen dietary formulation. Researchers compared hen strain, age and rearing systems using TA Tetra White (TW) and Hy-Line Brown (HB) hens at 44, 68 and 88 weeks of age while housed in either conventional cages, enriched systems, cage-free or free-range systems. Results yielded that enriched housing systems had lower levels of Magnesium and Manganese than conventional cages. Age only appeared to affect Manganese levels with younger birds having higher levels than older birds. Hen strain highlighted differences in Calcium and Copper levels with higher levels in TW hens, while HB eggs were higher in Iron, Magnesium and Manganese. Egg size did not vary within any of the defined parameters. Because of the small differences in egg mineral content, it is unlikely that age, genetic strain, and housing system would have any significant impact on human nutrition.

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