When to take the first cutting is an important decision for those desiring to harvest high-quality alfalfa. Estimating the relative feed value (RFV) of standing alfalfa can be accomplished by using PEAQ (predictive equations for alfalfa quality), a system developed at the University of Wisconsin and used in Illinois.|
PEAQ is a function of plant height (soil surface to stem tip) and stage of maturity (vegetative, bud, or flower). From these two factors, the estimated RFV and neutral detergent fiber of standing alfalfa is obtained. PEAQ can be determined by using a yardstick and a table, or a PEAQ measuring stick, available from many alfalfa seed dealers or companies.
You are encouraged to check the Illini PEAQ Website at http://peaq.outreach.uiuc.edu/. At this website you can see how to calculate PEAQ, view PEAQ values for Illinois (by region and by county), enter and track your own PEAQ values, and so on.
As a general guide, if 150 RFV alfalfa hay is desired, harvest when PEAQ indicates 170 RFV. Many times RFV will drop three to five points per day.
PEAQ is designed for 16- to 42-inch- tall alfalfa, but it is not intended to balance rations. It does not account for quality changes during harvest and storage. The procedure is most accurate for good stands of pure alfalfa with healthy growth.--Jim Morrison