A newborn calf's gut isn't ready to do much on its own at birth, it needs help getting there fast. This study compared calves fed straight colostrum for three days against calves fed a 1:1 colostrum-milk mixture, looking at how each approach shaped small intestinal development along with a couple of related hormone markers tied to gut growth. For producers weighing how much colostrum to feed versus stretching supply with milk, this gets at whether that tradeoff costs the calf anything on the development side.
"Altered mucosa-associated microbiota in the ileum and colon of neonatal calves in response to delayed first colostrum feeding" — T. Ma, E. O'Hara, Y. Song, A.J. Fischer, Z. He, M.A. Steele, L.L. Guan. J Dairy Sci. 2019 Aug;102(8):7073-7086.