Forrest Gump’s momma always said, “Life is like a box of chocolates, you never know what you’re gonna get.” In a way, feeding cows is the same. You never really know the true composition of the feeds and diet that make it to the bunk or what makes it into each cow. However, with some discerning choices in purchased feeds and appropriate sampling protocols, you can significantly reduce the uncertainty in diet composition and reduce the risk of under- or overfeeding a certain nutrient.

Many factors affect a plant’s dry matter (DM), crude protein (CP) or neutral detergent fiber (NDF) content, including differences in plant genetics, the soil in which it is grown, fertilizer application rates and methods, and the weather. A feed’s nutrient composition can also be influenced by harvest, processing and storage methods. In addition to all these identifiable causes of variation, there is also some degree of random, or unidentifiable variation.