increase font size
Waste milk has traditionally been fed to calves as it can’t be sent for supply. But is this a good idea? DairyNZ senior scientist Jane Lacy-Hulbert investigates.
The increased focus on responsible use of antibiotics has raised a question about waste milk’s value as a feed source for calves, and the risks this practice might pose to the wider environment.
Waste (or ‘red’) milk is produced by lactating cows when they’re sick and receiving antimicrobial treatment for diseases such as mastitis. It also applies to the milk produced in the withholding period, which can be three to four days after treatment.
Exposing a bacterial population (such as the calf’s developing digestive tract) to low concentrations of antibiotics may encourage bacterial growth with existing resistance genes. It could also lead to other bacteria mutating and developing new ways to resist antibiotics.
The risk is that calves consuming this milk will shed antibiotic- resistant faecal bacteria into the environment. This could have unintended consequences for your calves and for the future usefulness of the antibiotic.
This is backed by a substantial review published in the European Union in 2017. The review found that shedding was more pronounced by younger calves (two to three weeks old) than by six- to seven-week-old calves.
Fortunately this shedding wasn’t observed in calves fed colostrum from cows previously treated at dry-off with long- acting dry cow antibiotic products.
Unfortunately pasteurising waste milk won’t deactivate the residues as most antibiotics are heat-stable.
Although there are few studies on this aspect, it’s likely that antibiotic residues would interfere with calves establishing good gut bacteria, or that pathogens and viruses from older, sick cows could infect the young calf. If there were more antibiotic resistant bacteria present in the gut these issues would be harder to control.
Although waste milk may be a convenient feed for calves, is it worth risking the health of the replacement calf or the environment? One thing is certain: it cannot be fed to bobby calves, as the calf’s gut is likely to absorb the antibiotic residues and cause the carcase to be rejected.
• Find out more about calf care at dairynz.co.nz/calves
DairyNZ says its plantain programme continues to deliver promising results, with new data confirming that modest levels of plantain in pastures reduce nitrogen leaching, offering farmers a practical, science-backed tool to meet environmental goals.
As an independent review of the National Pest Management Plan for TB finds the goal of complete eradication by 2055 is still valide, feedback is being sought on how to finish the job.
DairyNZ has pulled together tactics that will help farmers improve on-farm efficiency and have positive benefits for the environment. These tactics are based on research, data, and lessons from leading farmers.
The design and construction of an effective dairy effluent system is a complex process.
After serving three as a DairyNZ director, Waikato farmer Chris Lewis is ready for another term.
NZPork has appointed Auckland-based Paul Bucknell as its new chair.
The Government claims to have delivered on its election promise to protect productive farmland from emissions trading scheme (ETS) but red meat farmers aren’t happy.
Foot and Mouth Disease outbreaks could have a detrimental impact on any country's rural sector, as seen in the United Kingdom's 2000 outbreak that saw the compulsory slaughter of over six million animals.
The Ministry for the Environment is joining as a national award sponsor in the Ballance Farm Environment Awards (BFEA from next year).
Kiwis are wasting less of their food than they were two years ago, and this has been enough to push New Zealand’s total household food waste bill lower, the 2025 Rabobank KiwiHarvest Food Waste survey has found.
OPINION: Sir Lockwood Smith has clearly and succinctly defined what academic freedom is all about, the boundaries around it and the responsibility that goes with this privilege.
OPINION: Should cows in NZ be microchipped?
OPINION: Legislation being drafted to bring back the controversial trade of live animal exports by sea is getting stuck in the…
