How much milk does a brown Swiss produce a year?

Holstein cows produce an average of 3.5% butterfat with an average of 17,000 pounds of fluid milk per year. That would be 595 pounds of butterfat per year. Holsteins are the highest total fluid milk producers, but are on the low side of percent butterfat and percent protein.

Even so, if you compare Holsteins to breeds that produce higher butterfat (like Jerseys and Guernseys), the Holstein will produce more total butterfat in a year due to the higher volume of fluid milk that they produce.