No. Sour milk is caused by bacteria or micro-organisms during fermentation; they produce too much lactic acid. It turns the milk sour and unpalatable, but that doesn't mean it's unusable.
Sour milk was used as food in a variety of ways. The simplest way was to drink sour milk when eating porridge or bread.
Lactic acid in the composition of fermented milk products stimulates the functions of various digestive glands, so it fosters the digestion process. The regular consumption of sour milk also improves the function of the intestines, helping to avoid constipation.
Many baking recipes call for sour milk, sometimes as a substitute for buttermilk. Learn how to make sour milk at home at Atcoblueflamekitchen.com.