Hippopotamuses produce two unique skin secretions (so unique they're named after the animal), "hipposudoric acid" and its analog "norhipposudoric acid". It gives the hippopotamuses' sweat a red coloration, commonly believed to be blood (it's not). The acids act as a sunscreen and antimicrobial. The pink coloration is the mixture of these pigmented excretions and the white mammalian milk.
Does that mean the milk will be salty because of the sweat?
The fluid actually isn't sweat. Sweat evaporates off the skin for cooling but a hippopotamus's "sweat" is a fluid that stays on the skin. Sweat is salty because it contains salts, including sodium and chloride (the same stuff that makes up table salt). Hippo sweat is made of different components so it may not be salty.
.... did you know the Milky Way tastes like run and smells like raspberries? (ethyl formate) https://www.howitworksdaily.com/the-milky-way-smells-of-rum-and-tastes-like-raspberries/
Alright, if you're going to have a personal chit chat then do that personally with gomail.
...hippo milk is pink?