A just completed road show has been giving vets the strong message to vaccinate young stock earlier against leptospirosis.
Leptospirosis is a highly infectious disease that can be passed on to humans handling farm stock either on farms or in processing plants.
Farmers and vets are most exposed to the disease, with about 120 reported human cases in New Zealand each year.
But there could be many times more unreported cases.
It's been most prevalent in the dairy industry and farmers contracting it often mistake it for a bad dose of the flu.
But it can also kill, as the death of a meatworker in 2008 showed.
Common practice up until now has been to vaccinate calves against the disease at about six months of age to stop them spreading it.
But advisor to the Veterinary Association's Leptosure awareness programme, Dr Roger Marchant, says the latest advice is to vaccinate earlier than that.
He says there is some evidence that earlier vaccination can stop calves shedding the leptospirosis organisms in their urine.
He says young stock should be vaccinated at 3 months old, so if they are spring born vaccinate before Christmas or before calves leave the property.
Dr Marchant says the Leptosure vaccination guidelines are being revamped following a Massey University review.