As milk prices bottom out for spring calving, many farmers will not be feeding milk replacer, but is it worth feeding waste milk instead?

Waste milk (WM) is milk that will not enter the bulk tank as it is not suitable for sale, it is usually from cows being treated with antibiotics for issues such as mastitis. 

Farmers have been advised against feeding WM for years now, but previous surveys have suggested that more than half of Irish dairy farmers still feed WM to their calves.

Waste milk

Feeding waste milk to young calves can have a number of associated affects that can cost more in the long run.

WM often contains large numbers of bacteria, especially from cows that have mastitis, and feeding it can potentially spread infection from your herd to the calves.

Several infectious agents such as E.coli and Johne's have been found in WM.

This means that calves fed WM are at a higher risk when it comes to diarrhoea, inflammation, and changes to gut bacteria that are important for digestion and immunity.

Another concern is that it has the potential for calves to develop and shed antimicrobial-resistant (AMR) bacteria.

Study

Teagasc recently published findings from a study carried out on its Moorepark facility which investigated the effects of feeding waste milk to calves.

The study involved feeding some calves with WM for the entire pre-weaning period (12 weeks), while other were fed WM between three- and five-weeks-old only.

According to Teagasc, there was no difference in calf weights or average daily gain pre-weaning, at weaning, or post-weaning.

The research found that the overall health was high throughout the study, with most calves showing no signs of illness before, during, or after weaning.

The research also found that there was no big differences in terms of respiratory issues like coughs or nasal discharge.

However the research identified that during the pre-weaning period, calves fed WM for the 12 weeks showed slightly better health than those not offered any WM.

But faecal scores from calves fed WM between three- and five-weeks-old were higher, indicating better gut health.

In addition to this antimicrobial-resistant bacteria was found on staff boots and feeding equipment used for calves fed WM.

Teagasc concluded that feeding WM may influence gut development and increase antimicrobial resistance, especially during early growth stages, however it does increase the spread of antimicrobial-resistant bacteria.

Teagasc advised farmers not to feed WM due to the potential risks such as the spread of antimicrobial-resistant bacteria and disrupted gut microbiota, especially during stressful periods.

However, the researchers did say farmers who do feed WM must only feed it from three days post-treatment for a limited time while maintaining an exceptional standard of hygiene.