Table 18.

Options to reduce antimicrobial residues from milk and colostrum

Measure to reduce antimicrobial residues	Evidence in support of the measure	Evidence against the measure	Advantages	Disadvantages
Incubation with β‐lactamases to reduce β‐lactam antimicrobials	Korycka‐Dahl et al. (1985) Horton et al. (2015) Used in the past in dairy industry to produce fermented products from contaminated milk inhibiting growth of lactic acid bacteria Used to some extent in FI	None	Effective Easy to apply Commercially available β‐Lactam antimicrobials are most frequently used in dairy cow therapy Relative short incubation time and effective at moderate temperatures	May need regulatory clarificationa Spectrum of activity of each type of β‐lactamases has to be investigated for the purpose of inactivation of all used β‐lactam antimicrobials Do not cover other families of antimicrobials than β‐lactams
Heat treatment or treatment with conditioned medium from bacteria producing cefotaximase to reduce cefquinome (4th gen. cephalosporin)	Horton et al. (2015) (only one study, only cefquinome)	None	Effective Relatively short incubation time and effective at moderate temperatures (10–50°C depending on method) Targeting one of the highest priority CIA	May need regulatory clarification for conditioned mediuma Not available as ready‐to‐use commercial product for conditioned medium Only applied for cefquinome in this study
Fermentation to reduce penicillin‐G and cefquinome	Keys et al. (1979) (penicillin‐G) Horton et al. (2015) (cefquinome)	None	Can be effective Can use starter cultures or rely on endogenous bacteria in waste milk. For the latter success would depend on type of bacteria present	May need regulatory clarificationa Milk needs to be heated to 37°C for a prolonged time (not effective at lower temperature) Fermentation would increase bacterial count of the raw milk which may require pasteurisation before feeding to calves Because mechanism of activity is not known it is uncertain which antimicrobials are destroyed in each fermentation pH of the milk may be acidic which may compromise calves feeding possibilities Does not cover other families of antimicrobials than β‐lactams
Combination of ultrafiltration and permeate washes to reduce penicillin	Kosikowski and Jimenez‐Flores (1985)	None	Effective Reconstituted milk is not altered significantly in relation to raw milk Has the potential to also be applicable to other antimicrobials than β‐lactams	Very complicated method to apply at farm level
pH increase to pH 10 to reduce cefquinome	Horton et al. (2015) (only 1 study, only cefquinome)	None	Effective Easy to apply and cheap	Milk unlikely to be palatable to calves Might have adverse health effects (adjustment to pH 6–7 may be needed) Lack of knowledge if this measure may be effective for a broader spectrum of antimicrobials
Electrochemical oxidation to remove tetracyclines	Kitazono et al. (2012) (only one lab scale study)	None	Experience exists for waste water treatment	Special equipment necessary Electrolyte (NaCl) has to be added to the milk Lack of knowledge if this measure may be effective for a broader spectrum of antimicrobials Milk fat reduces effectivity
Heat treatments to remove several antimicrobials	Well documented in scientific literature	Several studies showing that most antimicrobials are very heat stable	None	Not effective β‐lactams need sterilisation conditions (120°C for 20 min) to be degraded Destroy any potential beneficial bacteria

CIA: critically important antimicrobial for human medicine, e.g. 3rd–4th generation cephalosporins and fluoroquinolones, according to the WHO definition (Collignon et al., 2016; WHO, 2016). See Appendix A. FI: Finland.

^aIt is likely that this use would fall under the definition of technological feed additives according to Regulation 1831/20013 which would trigger a premarketing authorisation based on a risk assessment.