The economics of haying operations have been changing over the past decade. The cost of production, equipment and supplies, land, water, seed and fertilizer along with the demand for much higher quality forages have dictated new management practices, products and methods, to ensure profitability.
What is Relative Feed Value?
Relative feed value is an index that ranks cool season legumes (alfalfa) and grasses by potential digestible dry matter intake. It is calculated from digestible dry matter and dry matter intake.
Digestible dry matter is an estimate of the total digestibility of the feed and is calculated from percent acid detergent fiber (ADF)*.
Dry matter intake is an estimate of the amount of feed an animal will consume in percent of body weight and is calculated from percent neutral detergent fiber (NDF)**.
*Acid Detergent Fiber (ADF): The fibrous component represents the least digestiblefiber portion of forage or other roughage. This highly indigestible part of forage and includes lignin, cellulose, silica and insoluble forms of nitrogen but not hemicellulose.
**Neutral detergent fiber (NDF) includes insoluble fibers, hemicellulose, cellulose, lignocellulose, and lignin. ... Acid detergent fiber (ADF) is a subset of NDF, including cellulose, lignocellulose, and lignin. ADF is the least digestible portion of the feedstuff, so higher ADF equals lower calories.
Calculation of Relative Feed Value (RFV)
DDM = Digestible Dry Matter = 88.9 - (0.779 x % ADF)
DMI = Dry Matter Intake = 120 / ( % NDF )
RFV = (DDM x DMI) / 1.29