Animal Welfare 1

Research title:

Assessment of the impact on intestinal microbiota and risk of development of antimicrobial resistance due to feeding of calves with milk with high somatic cell count or containing residues of antibiotics (waste milk)

Tutor: Prof. Valerio Bronzo


Contact details

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State of the art 

In dairy farms, large amounts of antimicrobials are used for cure and control of disease. In many places, antimicrobial agents are integrated and routinely used management tool, and in many cases, farmers might not even be aware that they are using them or for what purpose. The large use provides favorable conditions for selection, spread and persistence of antimicrobial-resistant bacteria capable of causing infections in animals and humans. During the past two decades, there has been an increased awareness of the potential problems that selection of antimicrobial resistance among food producing animals could have on human health. Milk from cows receiving antimicrobial treatment during lactation or dry period contains substantial residues during the treatment and withdrawal period. The use of such milk for calves feeding will lead to increased fecal shedding of antimicrobial-resistant bacteria by calves. A range of possible options exist for restricting the feeding of such milk to calves, which could be targeting the highest priority critically important antimicrobials. A recent request from the European Commission (EC) to the European Food Safety Authority (EFSA), asked to deliver a scientific opinion on the risk for the development of antimicrobial resistance due to feeding of calves with milk containing residues of antibiotics, highlighted the problem related to some management farm practices (included use of waste milk for calves feeding), normally applied in dairy farms.



Aims of the project

The aim of this study is to assess the possible relationship between the use of waste milk (high somatic cell count or antimicrobials residuals) for calves feeding before weaning, intestinal microbiota changes and possible fecal spread of antibiotic resistant microorganisms. The study will be performed in dairy farms from Northern Italy where use of waste milk for calves will be assessed as a normal management farm practice. Calves feed with waste milk, both for high somatic cell count and presence of antimicrobial residues, will be compared with calves feed with milk replacer and sampled at different time point. Fecal and blood samples collected at calving, and weekly until weaning, will be used to assess hemochromocytometric analysis, electrophoresis of blood serum proteins, presence and spread of antibiotic resistant bacterial strains and microbiome analysis. For microbiome bacterial DNA will be analyzed by Miseq (Illumina) platform, to provide a more detailed knowledge of the intestinal microbial communities in calves feed by waste milk or milk replacer in order to assess their dynamics and possible interactions with enteric pathogens. In this way, useful information on the factors influencing calf health and possible development and spread of antibiotic resistant bacteria will be obtained, under a one-health approach point of view.


Recent publications of the tutor in the field 

1. LOCATELLI C., PIEPERS S., DE VLIEGHER S., BARBERIO A., SUPRÉ K., SCACCABAROZZI L., PISONI G., BRONZO V., HAESEBROUCK F., MORONI P. (2013) - Effect on quarter milk somatic cell count and antimicrobial susceptibility of Staphylococcus rostri causing intramammary infection in dairy water buffaloes. J. Dairy Sci., 96: 3799-3805. IF 2.55

2. CAGNARDI P., LOCATELLI C., FERRARESI C., BRONZO V., CARLI S., VILLA R., ZONCA A. (2014) - Pharmacokinetics in foremilk and antimicrobial activity of cephapirin following intramammary administration in healthy and Staphylococcus aureus infected cows. N. Z. Vet. J., 62: 146-151. IF 1.219

3. LOCATELLI C., CREMONESI P., BERTOCCHI L., ZANONI M.G., BARBERIO A., DRIGO I., VARISCO G., CASTIGLIONI B., BRONZO V., MORONI P. (2016) - Short communication: Methicillin-resistant Staphylococcus aureus in bulk tank milk of dairy cows and effect of swine population density. J. Dairy Sci., 99: 2151-2156. doi: 10.3168/jds.2015-9940. IF 2.57

4. OSPINA P.A., ROTA N., LOCATELLI C., COLOMBO L., POLLERA C., GIACINTI G., BRONZO V., CASULA A., ARPINELLI A., BROSSETTE V., FACCHI M., PATELLI A., RUGGERI A., BARBERIO A., POTENZA G., NYDAM D.V., MORONI P. (2016) - Randomized noninferiority field trial comparing 2 first-generation cephalosporin products at dry off in quarters receiving an internal teat sealant in dairy cows. J. Dairy Sci., 99: 6519-6531. doi: 10.3168/jds.2015-10807. IF 2.57.

5. LOCATELLI C., CREMONESI P., CAPRIOLI A., CARFORA V., IANZANO A., BARBERIO A., MORANDI S., CASULA A., CASTIGLIONI B., BRONZO V., MORONI P. (2017) - Occurrence of methicillin-resistant Staphylococcus aureus in dairy cattle herds, related swine farms, and humans in contact with herds. J. Dairy Sci., 100: 608-619. doi: 10.3168/jds.2016-11797. IF 2.408.