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Estimating Alfalfa Quality in the Field

May 3, 2002
When to take the first cutting of alfalfa is an important question for those desiring to harvest high-quality hay or haylage. 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 the past few years.

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 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 and companies.

You are encouraged to check the Illini PEAQ Web site at At this Web site you can learn 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 3 to 5 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 due to wilting, harvesting, and storage. The procedure is most accurate for good stands of pure alfalfa with healthy growth.--Jim Morrison

Author: Jim Morrison

The Pest Management and Crop Development Bulletin
Executive Editor: Kevin Steffey, Extension Entomologist

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