Origin of pigments in eggs traced by stable isotope ratio mass spectrometry

The δ13C and δ15N values of eggs was measured using an isotope ratio mass spectrometer to trace the origin of pigments in eggs. A total of 320 layer chickens were randomly divided into four groups that were fed diets containing different corn content and an additional four groups that were fed diets containing different amounts of added artificial pigment. The values of Roche color fan (RCF), δ13C, and δ15N of yolks were measured on Day 28 (early stage) and Day 56 (late stage). The results indicated that the RCF and δ13C values of egg yolk in each group increased with an increasing corn content, and significant differences were observed between groups fed diets with different corn content (P13C values of egg yolk in both groups were significantly different compared with their previous results (P0.05). For the varying pigment groups, the RCF values increased significantly with an increase in amount of added artificial pigment (P0.05). Additionally, no significant differences were found in δ13C values before and after pigment removal (P>0.05). In the varying corn content groups, a strong positive correlation (P13C values, but no correlation was found in the varying pigment groups. When the RCF values were the same in two groups, δ13C values showed significant differences. Thus, analysis of carbon stable isotope ratio (δ13C) in egg yolk can be used to trace the origin of pigment in eggs. ©, 2015, South China University of Technology. All right reserved.