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Learn how to analyze beef cattle nutrition

Issue Date: 11/9/2011
Last Updated: 11/9/2011 12:00:00 AM |

By Jack Stivers For managing beef cow nutrition, it’s recommended that a producer have his or her forages analyzed by a commercial laboratory so a feeding program can be designed that will economically meet the requirements of the cow herd. Forage quality analysis, often referred to as forage testing, involves determining nutrient levels and is one of the most effective forage management tools. This eliminates guesswork when trying to match forage and feed supplies to animal nutrition requirements, designing supplemental feeding programs and evaluating forage production. It is important to understand forage quality terminology to interpret forage nutrient analysis reports effectively. Following are definitions of and typical ranges for the various common components of a nutrient analysis report. • Moisture Moisture is water in the forage. Excessive moisture levels in hay crops can lead to hay heating, quality losses and even hay fires. Hay samples with moisture above 18 percent in round bale form and more than 20 percent in small square bale form have significant risk of heating that can lead to nutrient losses or even firs. • Dry Matter Dry matter is the air-dried component of the forage with all the moisture removed. To calculate dry matter content, simple subtract the moisture content from 100. Most dry hays often have a dry matter content of around 85 to 92 percent. • Crude Protein Crude protein is based on the nitrogen content of the forage and is calculated using the formula nitrogen x 6.25 = crude protein. Crude protein will include both true protein and non-protein nitrogen. Cattle can use both types to some varying degree. • Acid Detergent Fiber This value refers to the cell wall portions of the forage that are made up of cellulose and lignin. These values are important because they relate to the ability of an animal to digest the forage. As acid detergent fiber increases, digestibility of a forage usually decreases. • Neutral Detergent Fiber This value is the total cell wall, which is comprised of the acid detergent fiber fraction plus hemicellulose. Neutral detergent fiber values are important in ration formulation because they reflect the amount of forage the animal can consume. As neutral detergent fiber increases, intake will generally decrease. • Crude Fiber When crude fiber system was developed, it was thought to represent most of the cell wall portion of the forage. However, it was later discovered it didn’t account for some of the hemicellulose and lignin components. • Total Digestible Nutrients Total digestible nutrient is an estimate of the energy content of the forage. It is calculated by a formula that uses the acid detergent fiber, neutral detergent fiber, crude fiber and ash components of the feedstuff to give an estimate value of energy. Typically the greater the value, the more energy-dense the forage is. Typically the lower quality hays are in the 40 to 50 percent range, while higher quality hays are in the 50 to 60 percent range. In some cases, certain grass hays and alfalfa hays can be in the 60 to 70 percent range. (Editor’s note: Part two of this article will be published in next week’s Valley Journal.)