What is the first milk of a cow that is high in antibodies called?

The first milk produced by a cow after calving is known as colostrum. This initial milk is particularly significant because it is rich in antibodies, which are crucial for providing the newborn calf with immune protection during its early life. Colostrum is thicker and yellowish compared to regular milk and contains higher levels of nutrients and immunoglobulins that bolster the calf's immune system.

As for the other options, milk replacers are formulated products designed to substitute for the nutrients found in cow's milk, typically used in feeding orphaned or rejected calves. Skim milk is the liquid remaining after cream has been removed, and it lacks the high level of antibodies present in colostrum. Buttermilk, on the other hand, is a byproduct of churning cream into butter and does not possess the same nutritional profile or immune-boosting properties as colostrum. Therefore, colostrum is uniquely positioned as a vital source of nutrition and immunity for newborn calves.