At calving, a cow and her calf experience a suppressed immune system, making them vulnerable to disease and infection. When these animals co-mingle in a group maternity pen — especially one that's not cleaned thoroughly between calvings — they run the risk of picking up pathogens which cause infection or disease.

That's especially true for diseases, such as Johne's disease and salmonella, which can transfer to other animals in a group pen, says Ann Wilkinson, a technical services veterinarian with Pfizer Animal Health.

For example, a cow with Johne's disease may be shedding the mycobacteria which cause this disease at calving, Wilkinson says. That means a calf can easily contract Johne's from her dam. And, if you allow cows to calve in a group environment, you not only expose one calf to the disease, but you expose several other calves to it as well.

Thus, provide a clean and dry individual pen at calving to minimize a cow and her calf's exposure to harmful pathogens.