Calves are failing to achieve adequate passive transfer of immunity – even when colostrum quality appears good, suggests a study.
More than three-quarters of calves tested in a seasonal-calving dairy herd had inadequate passive immunity – despite colostrum testing at the recommended 22% Brix or above. All calves later developed scours.
Authored by Ryan Davies of Veterinary Technical Consulting and Dr Katie Denholm of Glasgow University, the study highlights the importance of testing calves for passive transfer using blood samples before they are seven days old.
The findings – from a herd in Northern Ireland – are particularly relevant for herds investing in dry cow vaccination, which provides antibodies in the colostrum to reduce clinical signs of diarrhoea caused by C. parvum bacteria.
This is because even when vaccine-derived antibodies are present in colostrum, calves will not benefit if absorption fails. The findings support the Royal Veterinary College findings which found failure of passive transfer in more than one in four UK herds.
The latest results were reported in the Vet Record. Dr Davies said: “It can often be a case of farmers jabbing the dry cows and thinking the job is done, and when they then see diarrhoea in calves, they assume the vaccine isn’t working.”
“As the case study in our paper has shown, that wasn’t the case at all. Calves were still getting scours, despite being vaccinated, as a result of inadequate colostrum management protocols.
In response, the Northern Irish farm introduced earlier feeding, so all calves were fed within 30 minutes of birth, colostrum enrichment using whole bovine colostrum powder to standardise quality.
Extended colostrum feeding was undertaken using whole bovine colostrum powder for the first 10 days of life. This offers local gut health benefits even after antibody absorption declines – although good hygiene is a critical factor.