The use of stable carbon isotopes to authenticate claims that poultry have been corn-fed

Abstract

In order to comply with EU legislation governing the marketing of poultry labelled as corn-fed, chicken must be fed a diet containing at least 50% (w/w) corn for the greater part of the fattening period; however, there are currently no reliable methods to authenticate this dietary claim for poultry. The procedure reported exploits the differences in the photosynthetic pathways between maize and other cereals such as wheat, rye, barley and oats and in their differing enrichments of the 13C stable isotope from atmospheric CO2. Resulting differences in 13C and 12C are measured by Stable Isotope Ratio Mass Spectrometry. A series of controlled feeding experiments have been carried out on two breeds of chickens, and the results showed that both the fat and protein contents of the bird changed consistently in line with both the quantity and duration of corn consumption. Blind testing of the method and examination of commercially grown corn-fed chicken showed that the 13C content of the protein was a reliable marker of the dietary status of the chickens.