UNITED STATES OF MINNESOTA Carbohydrate Nutrition and Manure Scoring

There are some elements of ration formulation for which we have no hard and fast rules. Carbohydrate supplementation is one of them. The 2001 Dairy NRC has done the best job to date in offering guidelines regarding the balance between forage & neutral detergent fiber (NDF) vs. nonfiber carbohydrates (NFC). However, there are a variety of factors that can affect what modifications to apply to those guidelines to achieve top production and animal health. To have the best sense of what changes to make, one needs a sense of how carbohydrates function in rations, knowledge of the factors that can affect how the cow performs, and examination of what the cows have to say about their interaction with the ration. Carbohydrates: NFC & NDF The two sources of carbohydrates in rations are neutral detergent fiber (NDF) and nonfiber (non-NDF) carbohydrates (NFC). Together, the carbohydrates account for 70 % or more of the dry matter and most of the energy in the ration. These carbohydrates differ greatly in their digestion characteristics and how we consider them in ration formulation. This paper will focus largely on NFC. NFC has typically been calculated by difference (100- crude protein- NDF- ether extract-ash; sometimes with the value of NDFCP added back). Although the terms NFC and NSC (nonstructural carbohydrates) have often been used interchangeably, they do not describe the same carbohydrates. NSC refers only to sugars, starch and other cell contents, whereas NFC includes some cell wall carbohydrates, as well. This very diverse array of carbohydrates does not function similarly in rations. Four categories of NFC are organic acids, sugars (mono- and some oligosaccharides), starch, and neutral detergent-soluble fiber (Figure 1)