Colored Milk (1979)

A grandson came to the village to visit his grandmother, who rarely rests in nature, which makes him look pale and sick. The boy likes the geese, the cow, and the local nature here. He gets involved in local life, starts making friends with animals, walks with them in meadows and lawns, and doesn't even notice how his grandmother's health turns into joy. And the reason for the transformation was the mysterious colored milk.

Unfortunately the movie Colored Milk is not yet available on HBO Max.