A simple and quick sampling tool to monitor antibiotic use in veal calves – a successful demonstration

• A study including 98 veal calf farms was carried out to compare alternative matrices proposed for novel monitoring strategies • A unique comparison was made between hair, animal wipes, pen wipes, manure and saliva • Animal wipes are an effective and easy way to monitor antibiotic use • Persistent antibiotic residues on veal calves or in the barn environment are also detected by wipe, manure and hair sampling In the Netherlands, more than 100 tons of antibiotics are used annually to combat microbial infections in animal husbandry. It is known that excessive use of antibiotics can cause development of antimicrobial resistance (AMR); a major human health risk. Therefore, the prudent use of antibiotics needs to be enforced within animal husbandry by implementing effective monitoring methods for detection of antibiotic use. Since the current monitoring methods based on sampling of edible matrices are lacking due to their short detection window and invasive character, previous research has suggested alternative monitoring based on the analysis of hair, manure and saliva, in which antibiotics can be detected well past the detection window of edible matrices of current monitoring strategies. Moreover, samples are non-invasive and can be taken during farming. Although effective monitoring strategies, some of these matrices can be challenging to sample and analyse. Therefore, as another simple alternative, we propose the collection of wipes from animals. In order to test the efficacy of animal wipes, wipes of the pen compared to the previously suggested monitoring matrices manure, hair and saliva, an elaborate practical study was performed, including 98 veal farms in the Netherlands. Based on the results of this study, animal wipes proof to be easy and equally effective in detecting administered antibiotics to veal calves meant for meat consumption as hair and manure. Saliva, on the other hand, was not as effective for the detection of used antibiotics in comparison to the other matrices. Furthermore, this practical study showed that wipes, manure and hair detected persistent antibiotic residues which still reside in the barn environment. Therefore, these sampling strategies are also a valuable tool in case of searching for substances that are not supposed to be omnipresent. However, to distinguish between recent use, historic use and superfluous use of the most commonly used antibiotics, more research is necessary to be able to better interpret the outcomes of wipe sample analysis.