The information below has been supplied by dairy marketers and other industry organizations. It has not been edited, verified or endorsed by Hoard’s Dairyman.

Waste milk occurs on farms where antibiotic treatment has been administered to cows. It cannot be sold for human consumption but as it contains valuable nutrients, it remains a popular source of nutrition for pre-weaned calves. It’s estimated that over half of the calves in the U.S. are fed waste milk that otherwise would be poured down the drain. Although nutrient-rich and inexpensive, there is risk of antibiotic residues in waste milk.

When calves are fed waste milk containing antibiotic residues, bacteria within the gastrointestinal tract can develop antimicrobial resistance. Research conducted at the University of Reading in England was undertaken to determine the effect of supplementing waste milk fed to dairy calves with Anpario’s Orego-Stim Liquid (a source of 100% natural oregano essential oil), on the population of antimicrobial resistant bacteria in their feces.

Calves were offered either waste milk supplemented with Orego-Stim Liquid for ten days (5ml per 2.5L milk twice daily) or a control diet of the same waste milk source without the addition of Orego-Stim Liquid. After ten days all calves were fed the same ration of unsupplemented waste milk and concentrates until weaning.

In the feces of control calves, 44.1% of the E. coli present were resistant to the 4th generation cephalosporin antibiotic cefquinome. In calves fed waste milk supplemented with Orego-Stim Liquid, only 12.6% of E. coli were resistant. In addition, calves fed the supplement shed Cryptosporidium in significantly lower amounts.

Orego-Stim was awarded a UK patent following the work, with the composition of the additive being effective in reducing antimicrobial resistance*. Waste milk is a valuable resource and this trial work shows that it may be possible to support calf gut health and enable the continued use of this vital calf feed.

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