Hi, is there any differences between countries about the milk fat level and what is the standard level of milk fat in dairy cattle ?

Milkfat can vary widely between breeds, diet, stage of lactation/ volume of milk produced, with diet being the variable that management can influence. When working with lactation curves, it usually makes the most sense to calculate and chart with 4% FCM (Fat Corrected Milk). Milkfat variations by country are mostly due to the diet at the locale. Although breed popularity still has a country by country bias, worldwide availability of top genetics is gradually diluting this variable.