Look at the picture here and decide which sample of hay you would buy if these were your two choices. Would you buy the more discolored hay on the left, or the greener hay on the right?
The decision may not be as easy as it sounds. First, Chris Parker, Morgan County Extension ag educator and columnist for forage columns in Indiana Prairie Farmer magazine, says the only way to know nutrient content for sure is to test the hay through a commercial lab.
At first glance you would assume the hay on the right with greener color would test higher in protein and TDN, or Total Digestible Nutrients. That means it will also rate higher in RFV, or Relative Feed Value. That score is in relation to an average score of 100. RFV values above 100 are desirable, but even values in the high 80's or 90's can be a good buy, depending on what you want to do with the hay.
Just because hay is discolored, especially if it is hay baled a year or more ago, doesn't necessarily mean it will be lower in nutritional value, or at least not that much lower, Parker says. Sometimes samples such as that one still test relatively well.
The second big factor is what you are going to feed it to, he says. If you're feeding gestating beef cows, the hay on the left may work fine until they get close to calving, when they might need more nutrients. If you're feeding it to lactating dairy cows and it doesn't test as high as the hay on the right, then you might opt for the greener hay.
The third factor is price. If the price of the greener hay is twice that per small square bale of the hay on the left and you're feeding beef cattle, the browner hay might still be the better purchase.