April 1999
Volume 2, Issue 2

Inside this Issue
Harvest Alfalfa Based on Quality Goals - Mark Sulc
Milk Prices Flatten as Milk Output Stays in High Gear!

Harvest Alfalfa Based on Quality Goals
Mark Sulc
The Ohio State University

How many times have you heard the statements: “Timely harvest is critical for achieving optimal quality of alfalfa forage” and “high forage quality is critical to good performance in high producing lactating cows”? But how do you know when alfalfa is at the optimal quality for cutting? How often have you harvested and stored alfalfa without any knowledge of its chemical composition? If you are like most of us you make a best guess, watch the weather forecast, and then decide when to start cutting. Having lab results of forage quality on the standing crop would be nice, but getting them is not practical. Now for the good news…you can quickly and easily estimate the forage quality of alfalfa in your fields, and you can do so with reasonable accuracy. Sounds too good to be true? Read on.

A method was developed recently at the University of Wisconsin to estimate alfalfa fiber composition of the standing crop. The Wisconsin method has been dubbed PEAQ, for Predictive Equations for Alfalfa Quality. The PEAQ method uses the longest stem and the most mature stem in an alfalfa sample to estimate neutral detergent fiber (NDF) concentration. The accompanying chart describes how to use this method. The charted values are calculated from a regression equation of the relationship between NDF concentration and stem length and maturity stage of alfalfa. The original method included a more detailed maturity staging scale, but we have found that a simple 3-stage scale (vegetative, bud, and flower) works just as well as the more detailed staging system. This simplification was agreed to in cooperation with the How reliable and accurate is PEAQ?  We have tested the PEAQ method in production fields across Ohio and over multiple years, locations, and cuttings. It has also been validated in New York, Pennsylvania, Wisconsin, South Dakota, and California. After collecting 545 samples across these six states, we can conclude that the PEAQ method does indeed estimate NDF with reasonable accuracy. The estimated NDF (using PEAQ) was within 3 units of the actual wet chemistry NDF in 77% of the samples we collected. In 58% of the samples, the PEAQ NDF was within 2 units of the actual value, and in 88% of the samples the estimated NDF was within 4 units of the actual NDF. The PEAQ method performed consistently across a wide range of environments. It worked as well in other states as it did in Wisconsin, where it was originally developed. An important advantage of PEAQ over other prediction methods (such as the GDD method) is that it can be used during the entire growing season, not just on the first crop. So it provides a reasonably accurate guide for timing harvests according to your forage quality goals all season long.

What should my forage quality goal be?  The NDF content of pure alfalfa forage should be near 40% in order to optimize profitability in a 50% concentrate ration fed to dairy cows. This will usually maximize cow performance and minimize supplementation costs. Optimal NDF concentration for pure grass forage fed to lactating dairy cows is between 50 and 55%. For mixed grass-legume stands (50:50 mix), the forage at feeding should contain 46 to 48% NDF.

When should I begin harvesting?  The PEAQ method can be used to monitor the NDF content as the alfalfa crop develops. Use your judgement of how often this needs to be done, but you should make a first estimate at least one week before your expected date of harvest. If the goal is 40% NDF in alfalfa at feeding time, then cutting must begin well before the standing crop reaches 40% NDF. Harvest and storage losses can raise the NDF concentration by 2 to 6 units under good conditions. In our experiences, NDF concentration of well-made silage is about 2 percentage units higher than in fresh forage. Losses with hay harvest will be higher. You also need to adjust for the time it takes to harvest all your acres. During the spring, NDF increases about 5 points per week. So a reasonable goal is to begin harvesting alfalfa when it reaches 35 to 36% NDF as estimated by PEAQ. Harvesting should be completed by the time the standing crop reaches an estimated 40% NDF, assuming the forage is to be fed to lactating dairy cows.

If grass is present in the alfalfa stand, begin harvesting earlier. How much earlier will have to be your judgement, based on the grass maturity and amount present. There are currently no methods for estimating NDF concentration of grasses or grass-legume stands. But in pure grass stands, harvesting should occur in late vegetative to very early boot stage in the spring (head still enclosed in the flag leaf), and at 25- to 28-day intervals thereafter. If the stand is over 50% alfalfa, then the first harvest date and intervals between cuttings should be intermediate between those for a pure grass stand and a pure alfalfa stand.

Precautions when using PEAQ.  Be sure to pay attention to technique. Measure the LONGEST stem in the sampling area from the soil surface near the base of the plant (as described in the chart), and correctly identify the MOST ADVANCED stage of maturity. The PEAQ method is designed for pure alfalfa stands, and will not accurately reflect the NDF concentration of mixed grass:alfalfa stands or weedy stands. The method is not reliable for alfalfa shorter than 16 inches or taller than 40 inches. The PEAQ procedure is NOT intended to replace laboratory analyses once the forage is stored. It should only be used to give a rapid first estimate of quality of the standing alfalfa forage for purposes of making informed harvest management decisions. Decisions regarding ration balancing should be based on laboratory analyses after the crop is harvested and stored.

Summary.  The PEAQ method provides a reliable guide for optimizing quality of harvested alfalfa. It is more reliable than timing harvests by calendar date, age, or by maturity stage alone. Although rainy weather can foul up the best laid plans, using PEAQ in conjunction with weather forecasts should help you come closer to your desired forage quality goal. It can help you decide the order in which to harvest different fields based on forage quality. The estimated NDF content may also be useful when deciding where to store the forage, such as putting lots of similar quality together.

Estimating Alfalfa NDF using PEAQ

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

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 (copies of PEAQ chart available by calling Michelle Milligan at 614/292-7374 or milligan.4@osu.edu) to determine estimated NDF of the standing alfalfa forage.  Example: tallest stem is 28 inches, most mature stem has buds, but no open flowers; NDF = 38.0.

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. Average all estimates for a field average.

NOTE: This procedure estimates alfalfa NDF content of the standing crop. It does not account for changes in quality due to wilting, harvesting, and storage. These factors may further raise NDF content by 3 to 6 units, assuming good wilting and harvesting conditions. This procedure is most accurate for good stands of pure alfalfa with healthy growth.

Milk Prices Flatten as Milk Output Stays in High Gear!
Cameron S. Thraen
Dairy Economist / State Extension
The Ohio State University

The Great Uniform Price Collapse - What is about to Happen?

WHEW! In my April report (put out March 25th) I stated that the March BFP would come in at $11.57 and explained what was behind the significant decline in the February BFP.  For March I was off by only 5 cents and I can live with it!   Now let's turn our attention to prices for April (to be announced on May 5).  Using the same logic that I took you through in the last issue (and if you missed it you can find it on my  OhioDairyWeb at the URL  http://www-agecon.ag.ohio-state.edu/faculty/cthraen/ohdairy/) I think that the April BFP will be up slightly from the March BFP and will be announced at $11.71.  My black box for coming up with this number is very transparent.  This increase is due to a slight increase of 6 cents in the product price adjustment and the base month price being at or near the $11.62 March BFP.

How does the Cheese price influence the Base Month Price?

Let's take a quick refresher on this topic.  The normal rule of thumb is a 10:1 ratio between milk price and cheese price.  The average cheese price reported by NASS in March was $1.31 per pound.  This gives the cheese plant gross revenue of $13.10 for each hundredweight of milk.  Now, suppose the cheese plant was your dairy.  Would you pay $11.62 for an input that was worth $13.10 on the marketing end of the game?  Surely you would if you could cover your operating margin!  I believe that cheese manufactures, in Minnesota and Wisconsin,  were  willing  to  pay
this  for  milk.   At   the  announced March BFP price of $11.62 and an average cheese price of $1.31, the 10:1 rule suggests that cheese plants in March experienced a gross margin of [$13.10 - $11.62] = $1.48 per 100 pounds of milk.  With this gross margin they could pay the $11.62, in fact they could pay a little more!   How much more is the real guessing game.  A normal margin runs around $1.05 per 100 pounds of milk.

What's Ahead for the April BFP and Class Prices?

With March margins in the $1.48 range, the best bet is that cheese plants very likely will have paid close to the announced $11.62 for milk.  The following table shows my method for getting a fix on the current month BFP.  The gross value of cheese and butter/powder for each 100 pounds of milk has not changed much from March to April.  Based on these gross values my calculations suggest that a BFP of $11.65 + $0.06 = $11.71 is a reasonable estimate. Looking at the CME BFP futures contract price trading on April 26th of $11.61, my estimate is not too far from the mark, although I am a little more bullish than the market.

                                       Cam's estimate of the April BFP
 
                                                                          Base Month                       Current Month  
                                                                             March                                   April
NASS Cheese Price                                               1.31                                     1.325
Nass Butter Price (AA)                                           1.293                                   1.00
NASS Butter Price (A)                                           1.202                                   0.91
NFDM Price                                                          1.01                                     1.00
Whey Price                                                             0.694                                   0.694

Change in Cheese Value                 +0.0914
Change due to Butter Market          -0.0272
Gross Change in Product Values     +0.06
Butterfat Differential                          0.112
Base Month Price Based on
                   Product Values            11.65
NASS Commodity Adjustment     +0.06
Estimate for BFP                         $11.71

Cam's Estimates for the April 1999 Class, Component and Uniform Price
(does not include adjustments for processor assessments, producer settlement fund, etc.)

Price Estimates                                         FMMO 33                             FMMO 36

Class I Price                                                 $12.31                                 $12.27
Class II Price                                                $10.57                                 $10.57
Weighted Average Differential Price              $0.14                                     $0.17
Skim Price  (per lb.)                                     $7.79                                     $7.79
Butterfat Price (per lb.)                                 $1.20                                     $1.20
Protein Price (per lb.)                                   $2.36                                     $2.36
Uniform Price                                               $11.85                                 $11.88
 
 

For comments on Buckeye Dairy News, contact:  Normand St-Pierre, Editor, 614-292-6507,
st-pierre.8@osu.edu.