Hen genetic strain and extended cold storage implications on physical egg quality from cage-free aviary housing system.

Authors: Jones, Deana; KARCHER, DARRIN - Michigan State University; REGMI, PRAFULLA - Michigan State University; ROBISON, CARA - Michigan State University; Gast, Richard

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/2/2017
Publication Date: 6/22/2018
Citation: Jones, D.R., Karcher, D., Regmi, P., Robison, C.O., Gast, R.K. 2018. Hen genetic strain and extended cold storage implications on physical egg quality from cage-free aviary housing system. Poultry Science. 97: 2347-2355.

Interpretive Summary: The US egg industry is in the mist of a rapid conversion to cage-free production due in part to market and consumer demand. Research is needed to understand the implications of the shift to cage-free egg production on egg quality. The current study compared 4 genetic strains of laying hens (2 brown shell strains, 2 white shell strains) housed in cage-free aviary systems and resulting eggs produced between 21 - 60 weeks of hen age. Eggs were also handled and stored under federally mandated conditions for 12 weeks to assess the changes in egg quality during retail and consumer use. Brown shell eggs were generally heavier than white shell eggs. One white shell strain produced eggs which were equivalent in shell strength to the strongest brown shell strain. This is a unique finding since up to this instance, white shell eggs have been reported as having weaker shells than brown eggs. Shell thickness as hens aged did not mirror shell strength as has been previously accepted. White shell eggs generally had greater whole egg total solids, while brown shell eggs produced more consistent total solids between the same 31 - 60 weeks of hen age period. The newly developed method of laser imaging the shell surface resulted in better assessment of egg size and shape compared to the previously accepted shape index measurement. The results of this study can be used by the US egg industry and food manufacturers as they transition to cage-free eggs in retail and food formulations.

Technical Abstract: In the US there is a sudden increase in the need for cage-free eggs in retail and food manufacturing sectors. As the US industry adapts existing and builds new cage-free housing structures, there is a need to understand the impact of cage-free systems and the corresponding management on egg quality. A study was conducted comparing two brown shell and two white shell hen strains housed in a cage-free aviary system. Eggs were collected at 21, 31, 42, and 60 wks of hen age. Each set of eggs were placed in cold storage and assessed at 0, 2, 4, 8, and 12 wks. A full profile of physical quality measurements was conducted on up to 18 intact eggs for each hen strain/egg storage/hen age analysis time. Egg weight increased approximately 10 g for brown shell and 14 g for white shell eggs as hens aged. Many of the properties monitored were significantly impacted by all three main effects (hen strain, egg storage, and hen age) resulting in three-way interactions. A brown and a white shell strain had significantly (P < 0.0001) stronger shells (44 N) than the remaining brown and white shell strains (42 N and 39 N, respectively). The current study also determined volume of shell, total length, maximum width, and percent length at maximum width to best indicate egg shape compared to shape index. One brown shell strain produced eggs with the most consistent shape characteristics over the hen ages monitored. White shell eggs from the cage-free aviary housing produced the highest whole egg total solids between 31 – 60 wks of hen age. Whereas brown shell eggs resulted in the more consistent level of whole egg total solids (22 – 23.5 %) during the same hen age range. The outcomes of this study can be utilized by the US egg industry in planning management strategies and market placement of cage-free eggs.