The human rumen

The cow is a ruminant, and cow's milk has evolved to promote bacterial growth in the upper small bowel; whereas human milk has evolved to discourage bacterial growth. Examination of the constituents of the two milks shows that their differences can be accounted for in terms of this difference in function. Children who are fed a calf's diet tend to develop a rumen. This may lead to chronic diarrhoea and malnutrition and may be a factor in diarrhoea ascribed to cow's-milk-protein allergy and lactose intolerance.