Egg Composition Affected by Hen Strain, Moulting08 January 2014
US - Egg composition and the percentage of yolk, albumen and shell were affected by hen genetics and whether the bird had been moulted, according to new research from North Carolina State University.
Both strain and moulting were found to affect nutrient composition and component percentages in eggs produced from laying hens.
The impact of egg colour, hen strain and moulting on the nutritional composition of eggs is limited, reported Ken Anderson of the Prestage Department of Poultry Science in a paper in Poultry Science.
His study compared nutritional composition and component percentages of cage-produced shell eggs with respect to egg colour, hen strain and moult.
Four strains were selected from the North Carolina Layer Performance and Management Test: Hy-Line Brown (HB) and Bovans Brown (BB), Hy-Line W-36 (HW) and Bovans White (BovW) were selected. Two groups from each strain were selected and two groups of moulted HW and BovW were selected and compared with their non-moulted counterparts to examine the moult’s impact.
Two sets of eggs from each replicate were collected simultaneously at 101 weeks of age. One sample of eggs was broken into a 12-egg pool stomached for three minutes (n=12 samples), then divided into six 50-mL tubes, sealed and frozen to be sent for cholesterol, n-3 fatty acids, saturated fat, monounsaturated fats, polyunsaturated fats, β-carotene, vitamin A and vitamin E analyses. The other set of 12 eggs was then assessed for component percentages.
The HW eggs had a greater (P<0.05) percentage of yolk than the BovW eggs of 28.12 versus 27.00 per cent, respectively; however, the BovW eggs had 1.0 per cent more albumen. The HB and BB egg components were not different.
Brown eggs were heavier (P<0.01) than white eggs.
White eggs had greater (P<0.0001) percentage of yolk and the brown eggs had greater (P<0.0001) percentage of albumen. The eggs from moulted hens had a greater (P<0.001) percentage of shell.
Total fat content in the samples was (P<0.05) higher in white eggs by 0.70 per cent than brown eggs due to increased saturated and polyunsaturated fats. The moulting of hens reduced (P<0.01) saturated fats by 0.21 per cent in the egg.
Vitamin A levels were higher (P<0.0001) in white eggs, and vitamin E was higher (P<0.0001) in brown eggs.
Anderson concluded from these results that strain and moult appear to influence nutrient composition and component percentages in eggs produced from laying hens.
Anderson K.E. 2013. Comparison of fatty acid, cholesterol, vitamin A and E composition, and trans fats in eggs from brown and white egg strains that were molted or nonmolted. Poult. Sci. 92(12):3259-3265. doi: 10.3382/ps.2013-03377
You can view the full report (fee payable) by clicking here.