Effect of iron glycine chelate supplementation on egg quality and egg iron enrichment in laying hens

Abstract

This study was conducted to evaluate the effects of iron glycine chelate (Fe-Gly) on egg quality of laying hens. A total of 810 laying hens (HyLine Variety White, 26 wk old) were randomly assigned to 6 groups, and each group consisting of 135 hens (5 replicates of 27 hens each). Hens in the control group received a diet supplemented with 60 mg Fe/kg as FeSO4, whereas hens in the other 5 groups received diets supplemented with 0, 20, 40, 60, and 80 mg Fe/kg from Fe-Gly, respectively. The study showed that dietary Fe-Gly treatments influenced (P < 0.05) the internal egg quality (egg weight, Haugh unit, albumen height), compared with the control group. However, dietary Fe-Gly supplementation showed few effects on the ultrastructure of eggshell in this study. The group of 60 mg Fe/kg as Fe-Gly was promoted (P < 0.05) in succinate dehydrogenase levels of liver and spleen compared with the 0 mg Fe-Gly/kg group, whereas the control (Fe/kg as FeSO4) group has no differences compared with the 0 mg Fe-Gly/kg group. The concentrations of Fe in the eggshell, yolk, and albumen were increased with increasing concentrations of Fe-Gly, where Fe-Gly (60, 80 mg Fe/kg) had higher (P < 0.01) Fe concentration than the control in yolk and albumen. The Fe-Gly groups (60, 80 mg Fe/kg) were influenced (P < 0.05) in transferrin, divalent mental transport 1, and ferroportin 1, compared with the control (FeSO4). In conclusion, Fe-Gly (60 mg Fe/kg) improved egg quality and egg iron enrichment. In general, there were no significant differences between Fe-Gly (40) and the control group in albumen height, Haugh unit, Fe concentration in eggshell and yolk. It revealed that FeSO4 could be substituted by a lower concentration of Fe-Gly and Fe-Gly may be superior to FeSO4 for egg quality in laying hens.

Keywords: egg quality; eggshell ultrastructure; iron enrichment; iron transport; laying hen.

Figure 1

Scanning electron microscope photographs of transverse surface and external surfaces of eggshells. The transverse ultrastructure of group of control (A), 0 mg/kg Fe (B), 20 mg/kg Fe-Gly (C), 40 mg/kg Fe-Gly (D), 60 mg/kg Fe-Gly (E), 80 mg/kg Fe-Gly (F), The transverse ultrastructure of group of control (G), 0 mg/kg Fe (H), 20 mg/kg Fe-Gly (I), 40 mg/kg Fe-Gly (J), 60 mg/kg Fe-Gly (K), 80 mg/kg Fe-Gly (L). Scale bars: 500 μm. A sample of 6 eggs per treatment was used to observe eggshell ultrastructure.

Figure 2

Effects of Fe-Gly supplementation in mammillary cone width in the eggshell of laying hens. Data are means ± SEM (n = 6).

Figure 3

Effects of Fe-Gly supplementation in the duodenal TF, DMT1, and FPN1 mRNA expression (A–C) of laying hens. Values are the fold-change relative to that control group and expressed as mean ± SEM (n = 6).