Description: Milk yield (MY) is the amount of milk and its quality during lactation. MY is an important economic and health factor closely connected with the health status of dairy cows, their reproduction, performance, longevity and milk composition and properties. The differences within milk indicators between high yielding herds with an average MY (H1 a H2) were tested in four herds. The files with 224 and 234 individual milk samples were collected in the summer and winter for three years. The files were balanced in factors of lactation. Group 1 had higher genetical value and had even better nutrition according to the MY