Separation of Dam and Calf after Birth
In a recent review of published research on the health consequences of the time a newborn calf spends with the dam
[Annabelle Beaver, Rebecca K. Meagher, Marina A. G. von Keyserlingk, and Daniel M. Weary "Invited review: A systematic review of the effects of early separation on dairy cow and calf health" J. Dairy Sci. 102:5784–5810 July 2019] the authors show that there are very mixed results of cow/calf separation compared to continued contact.
In some cases rates of scours, cryptosporidiosis, Johnes infection and respiratory illness were the same regardless of the management of cow/calf separation. In other research reports immediate separation seemed to improve calf health conditions while other reports showed better calf health when calves were allowed to remain with their dams.
The authors make this observation:
"The evidence we have reviewed indicates that prompt calf removal should not be viewed as a substitute for proper hygiene and management in the maternity area."
Thus, I conclude that my current recommendation for getting the calf out of the calving area as soon as she is able to stand is best for long-term calf health. Our goal is to prevent "manure meals" regardless of the source (bedding, dam, other adult cows).