Nutrient composition of fed rations differs from formulated rations due to day-to-day variation in dry matter (DM) content and nutrient composition of forages, as well as mixing wagon variation and sorting.

Combines have been monitoring yield since the mid-90s. Back then, forage yield monitoring was still in development. However, yield monitors for forage harvesters have made great progress in the last 10 years. We are familiar with the importance of calibrating the yield monitors on combines, and now need to pay similar attention to forage harvesters.