As normal, differences in the chemical composition of milk across breeds are reflected in the milk clotting time and its
rheological properties.
 The content of casein is the main characteristic representative of the milk rennet coagulation.
To get a good quality rennet curd that provides for high quality and yield of cheese, we need the content of casein to be at least equal to 2.5%. 
Studies conducted to measure the duration of milk coagulation (clotting), when using enzyme rennet,
indicate that in case of both, high and medium milk yields, the shortest coagulation time, equal to 17 min, is observed for
Jersey milk, while coagulation of Simmental milk takes 22 min.