The highest lactose percentage are found in the milk of

The highest lactose percentage is found in the milk of humans.
Lactose concentration in bovine milk is about 4.8%. People with lactose intolerance lack the enzyme, beta-galactosidase or lactase, to break down lactose into glucose and galactose during digestion.
All milk, raw or pasteurized, contains lactose and can cause lactose intolerance in sensitive individuals.