Re-authorization of gelatin and collagen of ruminant origin in non-ruminant feed: a new analytical challenge for the control of the feed ban

Description of the subject. A recent revision of the feed ban provisions authorizes the use of ruminant collagen and gelatin in feed for non-ruminant farmed animals. This authorization will promote the use of former foodstuffs (FFS) in poultry and pig feed. Objectives. The study aimed to investigate how these ruminant materials could impact the capacity to detect processed animal proteins (PAP) of ruminant origin in feed using the official PCR method and to evaluate the added value of a mass spectrometry protocol in development. Method. Presence of ruminant DNA in samples of collagen hydrolysate, gelatin and FFS collected from the industry was assessed using the official DNA extraction and PCR method. This allowed to evaluate the PCR inhibition properties of gelatin and collagen. The same samples were also submitted to a mass spectrometry-based proteomics (UHPLC-MS/MS) protocol targeting ruminant proteins, including collagen, to distinguish between ruminant by-products (unauthorized or authorized). Results. The results show the complementarity of PCR and UHPLC-MS/MS approaches in the context of the use of former foodstuffs in animal feed. Their combination has allowed to evidence that the presence of ruminant DNA in samples containing FFS was more linked to the presence of milk than to the presence of gelatin. On contrary, some samples have shown an increase of the cycle threshold value (Ct) that could correspond to an inhibitory effect due to gelatin addition. Conclusions. In the context of the circular economy, FFS is an interesting source of nutriment for animal feed. However, due to the presence of dairy ingredients, interference with official methods giving false suspicion of prohibited materials is to be expected. Furthermore, a masking effect of the presence of PAP due to a PCR inhibitory effect by FFS is also possible.