Crop Cure - Alfalfa Haylage

The proven preservative for all forages.

Forage Facts

June 2003

In This Issue . . .

- Estimating Relative Feed Value of Alfalfa

- Estimation of alfalfa RFV using PEAQ

- Alfalfa Maturity Stage Descriptions

- The Pros and Cons of PEAQ

Estimating Relative Feed Value of Alfalfa

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.

Table 1. Estimation of alfalfa RFV using PEAQ.

Step 1: Choose a representative 2-square-foot area in the field.

Step 2: Determine the most mature stem in the 2-square-foot sampling area using the criteria shown in the table at right.

Step 3: Measure the length of the tallest stem in the 2-square-foot area. Measure it from the soil surface (next to plant crown) to the tip of the stem (NOT to the tip of the highest leaf blade). Straighten the stem for an accurate measure of its length. The tallest stem may not be the most mature stem.

Step 4: Based on the most mature stem and length of the tallest stem, use the chart at the right to determine estimated RFV content of the standing alfalfa forage.

Step 5: Repeat steps 1 to 4 in four or five representative areas across the field. Sample more times for fields larger than 30 acres.

NOTE: This procedure estimates alfalfa RFV content of the standing crop. It does not account for changes in quality due to wilting, harvesting, and storage. These factors may further lower RFV content by 10 to 20 units, assuming good wilting and harvesting conditions. This procedure is most accurate for good stands of pure alfalfa with healthy growth.

Length of tallest stem	Late vegetative stage	Bud stage	Flower stage
—inches—		RFV
16	237	225	210
17	230	218	204
18	224	212	198
19	217	207	193
20	211	201	188
21	205	196	183
22	200	190	178
23	195	185	174
24	190	181	170
25	185	176	166
26	180	172	162
27	175	168	158
28	171	164	154
29	167	160	151
30	163	156	147
31	159	152	144
32	155	149	140
33	152	145	137
34	148	142	134
35	145	139	131
36	142	136	128
37	138	133	126
38	135	130	123
39	132	127	121
40	129	124	118

Alfalfa Maturity Stage Descriptions

Maturity Value	Description
Late Vegetative Stage	Stem length less than 12 inches.
Bud Stage	One or more nodes with visible buds. No visible flowers.
Flower Stage	One or more nodes with open flower(s).

The Pros and Cons of PEAQ

The Pros of PEAQ

Simple, fast, and inexpensive

Robust across a wide range of environments

Performs well over all growth cycles during a season

Real-time so no waiting for results

The Cons of PEAQ

Results are highly dependent on good sampling technique

Equation is calibrated for only PURE alfalfa stands

Does not work well with fields that have poor alfalfa stands or alfalfa suffering from waterlogging stress

Does not provide reliable estimates of NDF in alfalfa stands that are less than 16" or over 40" tall

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We reserve the right to change product specifications at any time. The information contained here is reasonably accurate at the time of posting, however we rely on the warranty and product specifications on the products themselves, not the information on the site. Crop Cure^® is a trademark of Domain, Inc. registered in the United States Patent and Trademark Office. Copyright © 2001, 2002 Crop Cure^®. All rights reserved.

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