Animal Health

Milk additives: Do you know what you’re feeding?

By Gemma Chuck

OVER THE past decade, the availability and popularity of milk additives has increased with many dairy farmers.

In Australia and New Zealand such additives are frequently added as a powder to whole, unpasteurised milk, prior to feeding to replacement calves.

This article discusses the common ingredients in milk additives and their potential value to improving calf health.

What do milk additives contain?

There is a plethora of commercially available milk additives, all containing variations of similar groups of ingredients.

The most common groups include vitamins, minerals, prebiotics, probiotics, ionophores and antibiotics.

Other ingredients include enzymes, yeasts and antioxidants.

The role of each of these ingredients can become confusing but farmers and calf rearers should be fully aware of what they are feeding their calves and the reasoning behind it.


The most common vitamins that are included in milk additives are Vitamin A, D, E, C and B-group vitamins. In any healthy animal, these vitamins aid in metabolism and maintenance of various tissues and organs.


Minerals nearly always feature in milk additives and commonly include zinc, manganese and iron and the trace elements copper, cobalt and selenium.

They have a diverse range of functions in the body and are generally required for metabolism and maintenance of organs.


Prebiotics are non-digestible food ingredients that, when consumed in sufficient amounts, can enhance the growth and/or activity of orally administered probiotics and/or existing beneficial gut bacteria.

The most commonly used prebiotics are carbohydrates, such as oligosaccharides or dietary fiber with low digestibility.

It has been suggested that several types of oligosaccharides have specific functions in calves, including blocking the colonization of harmful bacteria in the gut.

Supplementation with prebiotics may improve the growth performance of calves in either the pre- or post-weaning stage.

Similar to the case of probiotics, the observable benefits of prebiotics are likely to be minimal when calves are generally healthy.

Research to date has shown mixed results on whether prebiotics have any apparent benefit on body weight gain, feed efficiency or health measures. Further research is required to provide definitive evidence.


The Food and Agriculture Organization and World Health Organization has defined probiotics as “live micro-organisms which, when administered in adequate amounts, confer a health benefit on the host.”

The most common micro-organisms used in probiotics for calves are Lactobacillus and Bifidobacterium bacteria.

These probiotics have the potential to enhance gut health by stimulating the development of healthy gut bacteria, preventing harmful bacteria from colonizing the gut, increasing digestion and improving gut immunity.

Research measuring the effects of probiotics added to diets of young calves has been equivocal. In some studies, improvements in animal performance have been reported; in others, no effect of the inclusion of probiotics has been found.

The positive effect of probiotics has been observed in less healthy calves, reared in challenging environments. In stressed conditions, probiotics may help reduce the risk or severity of scours.

However, a better understanding of how the different probiotics work in relation to other gut bacteria and immune system is required.

Probiotics can be misused on the farm leading to a poor or non-existent response. It is worth remembering that probiotics are living bacteria and they must be handled carefully to maintain viability.

Always check the expiration date and store according to the manufacturer’s instructions. Possibly the most important point is that adding probiotics to antibiotic milk will defeat the purpose of including the probiotic in the first place!


The two registered ionophores for use in cattle are lasalocid (Bovatec®, Zoetis) and monensin (Rumensin®, Elanco).

At therapeutic levels, they aid in the control of coccidiosis in young calves and can help improve feed conversion efficiency.

Either ionophore can be included in a milk additive but be aware that they are also commonly included in calf milk replacers and commercial calf concentrates.

Both can cause toxicity if ingested above the safety threshold. It is important to check the ingredients of any calf milk replacer, milk additive (powdered or soluble) and calf concentrate for the inclusion of ionophores.


On some farms, prophylactic antibiotics have been used to maintain the performance of calves and reduce the risk of scours.

However, the use of mass in-feed antibiotics is not considered good antimicrobial stewardship as there is increasing global evidence of antibiotic resistance in both humans and animals.

Antibiotics should only be used when they are needed to treat existing bacterial infections.

Appropriate storage, dosage, route of administration, observation of withholding periods and records should be kept for all treatments.

The use of prophylactic antibiotics in every calf is not sustainable in the long-term and is strongly discouraged.

Commercial milk additives are generally not medicated with antibiotics but custom-made additives do exist and it is essential that you check the label, know what you are feeding and why.

In summary, there are a large number of commercial milk additives available, often with a multitude of claims and testimonials.

It is recommended to consult with your veterinarian before using a milk additive to help identify specific active ingredients, concentrations, modes of action and data supporting the claims. Ingredient interactions with other dietary components should also be considered.

• Gemma Chuck is an adviser with Apiam Animal Health.


“Effects of Probiotics/Prebiotics in Cattle Health and Productivity”, Uyeno, Y., Shigemori, S., Shimosato, T. (Microbes and Environments, 2015)

“Probiotics in Calf Feeding Programs”, Quigley, J. (Calf Note #91, 2003)