Dairy calves are difficult to keep alive in some cases because of a lack of immunity and stress from being removed from the cow after birth and fed milk replacer. In the past, some calf milk replacers had antibiotics to help prevent infection that is common in these calves.

Essential oils are being studied to see if they can have a positive effect on immunity and a calf’s overall health. However, the publication Dairy Herd Management points to concerns that the development of antibiotic resistance has ended the need to supply low-grade antibiotic supplementation in most cases.

To aid in increasing immunity and preventing illness, South Dakota state evaluated the use of a combination of essential oils and prebiotic products to add to colostrum or milk replacer. It was hoped these products would increase the calf’s immunity and improve appetite to reduce health challenges and the stress experienced by newborn calves.

The supplements mixed with colostrum or milk replacer contained a blend of oregano and thyme essential oils and arabinogalactan, a prebiotic supplement. The study used 61 calves and compared the effects of the supplement given with colostrum or with milk replacer only. The control group was not treated with the supplement.

The calves were weaned at 42 days and the study showed the growth of the calves was similar in all groups. Calves fed colostrum showed higher immunoglobulins signifying increased immunity.

A study done in China evaluated a similar product added to calf starter grain. The supplemented calves had greater dry matter intake and better food conversion. Another study out of England showed that calves given liquid oregano had fewer resistant organisms in their intestinal tract and shed fewer organisms of cryptosporidium, an intestinal parasite that can cause weakness and diarrhea.