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Measuring cattle feed quality in the field

A new system allows for bale-by-bale feed value testing

In challenging economic times it is more important than ever to know the value of the alfalfa forage you are feeding your dairy or beef cattle. Whether you are blending alfalfa in a ration to maximize lactation, fertility and calf growth, or utilizing lesser-quality hay for dry cattle or replacements, you want to know that you are consistently getting the most value for your dollar.

Many of us have relied on core samples and traditional lab tests for years. Although we have all dealt with some variability between labs, the far greater problem is sampling the crop. With traditional core testing it is difficult to get a sample that represents the entire stack. In addition, it’s common to have significant variation with a given bale. The challenges compound as we unknowingly add unrecognized variations in quality into feed rations, and then witness unexplained fluctuations in the cattle’s production/performance levels.

Today there is a new technology emerging in the arena of relative feed value (RFV) testing for alfalfa hay. Because it provides the vital data for every bale produced, this system will show precisely what relative feed value each bale is bringing to the ration. Hay producers will also find it to be a great marketing tool.

This new method of measuring RFV was developed by Harvest Tec of Hudson, Wisconsin, and tested against lab results of individual bales from eight farms over six states since 2013. Because the system calculates the RFV on every bale as it is produced, the hay can be sorted into grades as it is stacked, and therefore be shipped to the customer with the same consistent RFV, bale for bale.

How RFV works

To use this technology, the hay producer acquires the software program from his equipment dealer, such as AGCO, New Holland and others, and downloads the program into the applicator or moisture-reading system on the baler. The operator then takes a scissor sample just before cutting, or a windrow sample at the time of cutting, and sends this sample to a lab.

At the time of baling, the operator enters the data from the lab sample into the system. The information from the sample is used to calibrate the system, allowing for the quality of the stand including variations in maturity and other factors.

“Grabbing a few windrow samples, sending them into the lab, and entering the results when I start is a lot easier than trying to core representative bales later on,” says Gary McManus, owner of one of the test farms in Lakeview, Oregon.

Then as the operator bales the hay, the system uses the information from the lab sample as a baseline, representing the stand before any leaf shatter. As the baler operates, dual star wheel sensors measure crop moisture readings 96 times every three seconds to determine a moisture level of plus or minus one per cent accuracy. The baler’s scale provides the bale weight to within two per cent accuracy.

Based on the premise that the majority of the nutrient value of alfalfa is in the leaf, and that more density equates to higher leaf-to-stem ratio, the system analyzes the moisture content and bale weight data. It then calculates the dry matter density and the RFV of each bale produced based on the sample previously sent to a lab. The operator can then use this information as it appears on the system’s screen to calculate an average for a field.

A bale-tagging system can also be used to attach a radio-frequency identification tag (RFID) that can be read with a hand-held or stationary scanner from the point of retrieval from the field all the way to the feed ration.

The RFID tagger attaches a vinyl tag containing an RFID chip to the No. 6 twine on the bale; then writes valuable information to the tag before the bale is ejected from the chamber, including: bale moisture, weight, RFV, bale number, the time the bale was made, field location, and more.

System tested

Dr. Allen Young, Utah State University, performed some the first comparative tests during the crop season of 2013. This initial work was performed on farms owned and operated by Utah State University Agricultural Experiment Station. Samples were taken from 546 bales from three fields over three cuttings.

“The system seems to work and appears to be a practical way to get a reasonable approximation of the quality of hay as it comes out of the field…” says Young. (For Young’s full report, visit, Relative Feed Value)

In addition to the preliminary RFV testing to determine the accuracy of the system, Young further sorted alfalfa bales into a feed ration balancing program to determine what effect this would have on projected milk output based on (metabolizable energy) ME and (metabolizable protein) MP.

These diets were formulated to utilize a high-forage diet. It is important to keep in mind that alfalfa grown in the intermountain area is more consistent that that grown in some other regions due to growing conditions.

“However, it is obvious from the scenarios where hay was sorted by CP per cent and RFV that there is variation within a field that can show changes in milk production of about three to four pounds ME milk, or four to six pounds MP milk (depending on the field; in our rations MP was more limiting than ME),” says Young.

Farmers say it works

Over the past two growing seasons additional private studies have been performed on eight farms across six states, culminating in over 3,000 bales tested by the in-field RFV system and compared with core samples sent to conventional laboratories.

These bales were produced under different conditions of temperature, alfalfa varieties, cuttings, irrigated and non-irrigated fields, and made by different makes of balers and bale sizes. The results uniformly demonstrate that the bales tested by the in-field RFV system closely follow the values generated by laboratory tested core samples.

“Our calculated value represents the RFV of the entire bale,” says Jeff Roberts, president of Harvest Tec. “We feel this system is revolutionary in the production of alfalfa. We are adding precision to the testing of hay that was not available before.”

Don Leonard of Brush Colorado, participated in the study in 2014. “The values from the Harvest Tec system on the baler are pretty close to the values coming back from the lab taken with a Colorado Hay Probe — within five points and that is pretty amazing,” says Leonard. “What has surprised me is the difference in RFV from bale to bale. The Harvest Tec system picks that up.”

Gary McManus, of Lakeview, Oregon,says “What is really useful is having the RFV on the screen while I am baling. I thought as moisture increases, RFV would also increase, which I learned is not always the case. I went out one morning and was watching the RFV monitor, thinking ‘this hay should test better than that,’ so I shut down and went back to the house. I came back to that field later that night and sure enough, the RFV jumped 20 points over what it had been that morning.”

To learn more about the RVF testing system visit

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