A study by the Graham Centre for Agricultural Innovation at Wagga Wagga has found colostrum from more than 80 per cent of a sample of dairy cows did not contain adequate antibodies or meet microbiological quality standards.
Research leader Dr Angel Abuelo said colostrum, the milky substance produced by cows soon after giving birth, played a key role in developing a newborn calves immune system.
Therefore the results of the study, which was based on a survey of more than 100 dairy farms and samples collected from 23 dairy operations, suggested a large number of calves could be susceptible to illness.
"Calves rely on the antibodies they absorb from colostrum to fight infections during early life," Dr Abuelo said.
"In addition to antibodies, colostrum also contains hormones and growth factors that help the calves adapt to the life outside their dams' womb."
Dr Abuelo said the levels of antibodies in colostrum was partially dependent on the cow's status during pregnancy, with nutrition, stress and vaccination protocols all playing a role.
However, he believed it was when the colostrum was collected that was most significant.
"The faster the colostrum is collected following birth, the higher the amount of immunoglobulins or antibodies will be," Dr Abuelo said.
"Most likely, the main factor behind decreased immunoglobulin content was delayed collection following birth of the calf."
Dr Abuelo said ideally colostrum should be collected right after birth or within the first few hours.
"If cows are just checked for calving a few times per day, it is unlikely that this can be achieved," he said.
Low microbiological quality could also be due to infections in the cows' udder or poor hygiene during colostrum collection and storage.
"Hygienic collection of colostrum (cleaning and disinfecting teats and udder prior to collection), rapidly cooling down or freezing colostrum if not used fresh, and using cleaned and disinfected calf feeding apparatuses are key to decreasing the bacteria present in the colostrum fed to calves," Dr Abuelo said.
He said increased awareness of recommended practices for calf management and feeding would make a significant difference.
He also suggested there should be more input from vets during the process.
"The rates of calf illness and mortality on several of the farms studied were higher than industry targets," Dr Abuelo said.
"But the research indicates these targets are achievable and we believe that vets have a key role to play."
The full results of the study were published in the Journal of Dairy Science.