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Hay Analysis

Looks Like Greek To Me!

By John Kirchhoff

For many sheep producers, purchasing hay is like ordering dinner at a Chinese restaurant. There’s a bunch of words you don’t understand and after you get it, you’re not quite sure what you just bought. The old “$2 a bale” marketing approach is fast disappearing as more hay producers price their hay based upon its feed value.

Anymore, buying hay goes something like this: You show up at the seller’s farm and he points at some beautiful green, fine stemmed alfalfa and says, “This fourth cutting had acid and has a RFV of 185 but that first cutting, bleached stuff over there is only 125. I charge a dollar a point per ton, which do you want?”

That’s when you begin wondering if Yoda from Star Wars didn’t die after all, but instead took up selling hay.

While you ponder that possibility, he shoves several pieces of paper labeled “Forage Analysis” under your nose. You’ve never looked at a forage analysis report before and there are strange words like CP, ADF, NDF, TDN, RFV and DM to list just a few.

To make things worse, there are all sorts of numbers behind those letters. Whew! This reminds you of high school algebra class!

Bewildered, you shuffle the papers, mumble “U-hum” and confidently order up the green stuff. Two hundred and fifty dollars later, you have a pickup load of pretty green hay and a piece of paper that must have been written by either Einstein or space aliens.

Let’s see what all the letters and numbers mean. Here are a few of the more important things you’ll find on reports.


You know, like water. If it says 26% “as-fed basis,” that means each pound of forage is 26% water and 74% is dry matter (hay). Put simply, that 50 pound bale of soft, pliable hay consists of 37 pounds of hay and 13 pounds of water. By comparison, that dry, slightly crunchy 14% moisture bale has 43 pounds of hay and only seven pounds of water in a 50-pound bale. This seems pretty insignificant until you calculate how much water you’ve bought over the course of a winter.

When feeding hay, a 160-pound ewe is going to require around 4.5 pounds of dry matter per day to satisfy her needs (although maybe not her appetite). It takes 5.7 pounds of 26% hay to fill her up but only 5.1 pounds of 14% hay. If you feed $140 per ton, 26% moisture hay for 120 days, it’s going to take an extra $5 worth of hay per ewe to get the same amount of dry matter compared to the 14% moisture hay.

When hay has been treated with “acid,” it means a preservative such as proprionic acid was applied at baling to retard mold growth.

Hay baled at a moisture content below 18% is usually too dry for mold to form and is rarely treated. Applying acid allows the hay to be baled at higher moisture, helping retain leaves and is also quite beneficial when a big rainstorm is brewing on the horizon.

With untreated hay, moisture content above 20% encourages mold growth and the subsequent heat formation (115-125 degrees) produces mold dust and caramelizes sugars, turning the hay brown. Animals readily eat it because of the sugars but the heat renders proteins and carbohydrates less digestible. High temperature (130-140 degrees) leaves the hay protein almost 100% unavailable and extremely wet untreated hay can reach temperatures 150-200 degrees, high enough to cause spontaneous combustion.

High moisture hay is easy to spot. The stems will be very soft and pliable while the stems of dry hay tend to crack or break when bent. Often times moisture will condense on the underside of metal roofs overnight if the hay is being stored in an enclosed area with poor ventilation. If the hay seems wet, ask if it has been acid treated. Recently treated hay often has a vinegary odor but the odor dissipates with time. If it hasn’t been treated, reconsider your purchase because of the potential for mold formation, dry matter and nutritional losses.

Crude Protein (CP)

When a laboratory tests forage or other feedstuffs for protein, they’re actually measuring the nitrogen content. The protein value is then calculated from the nitrogen content.

The protein content of forage consists of true protein and non-protein nitrogen. You can usually accept this protein figure as accurate unless you have something like ammoniated hay. Anhydrous ammonia (a non-protein nitrogen source also used as fertilizer) raises the protein content of low protein hay by providing additional nitrogen and is sometimes used as a preservative. The lab test detects all of the additional nitrogen but in actuality, animals are able to utilize only a portion of this type of nitrogen. Ammoniated hay testing 10% CP will not provide an animal with the same amount of usable protein as ordinary 10% CP hay. Moisture in hay “dilutes” protein figures and makes comparing the results of one sample to another like comparing apples to oranges. The lab test will probably have two protein figures, one as-fed basis and a higher dry-matter basis figure. Use the as-fed basis when calculating rations because it takes into account the “more moisture equals less hay” factor. The dry matter figure is calculated at 0% moisture, so it allows samples to be compared oranges to oranges. Normally, the higher the CP number, the better the quality.

Acid Detergent Fiber (ADF)

The ADF figure refers to the portion of the plant cell wall that is made up of lignin and cellulose, which is highly indigestible and is the sort of stuff you find in cardboard. With ADF numbers, the lower the number, the better the hay quality. Low numbers equate to high digestibility.

Neutral Detergent Fiber (NDF)

The NDF rating is a lot like ADF, except it includes all of the cell wall and includes hemicellulose. Sounds like something found under the hood of a Dodge, doesn’t it? This number is important because it reflects the volume of forage an animal is able to consume. With NDF numbers, the lower the number, the more forage the animal can consume. And remember getting “Serta the sheep” full of feed is the name of the game.

Total Digestible Nutrients (TDN)

The TDN score is an estimate of the percentage of the forage that is digestible based upon several figures. The higher the TDN number, the higher the quality. The problem I see with this figure is some labs use different formulas to arrive at it and that makes it tough to compare test results from different labs.

Relative Feed Value (RFV)

Nutrition Requirements Chart
Nutrition Requirements Chart

Buying top

This number is an index that allows you to place a numerical value on the overall feed value of the forage. This number makes it possible to compare one forage to another on a level playing field, whether it’s comparing alfalfa to alfalfa, alfalfa to fescue or dry hay to growing pasture.

The ADF (digestibility) and NDF (intake) figures are used to calculate the RFV number. Full bloom alfalfa at 100 is the benchmark to which other values are compared. Leafy, less mature alfalfa would normally have a higher number, indicating more nutritious forage, pound for pound. If that same less-mature alfalfa had been rained on for a week and had few leaves left, it would have a lower number and be less nutritious, pound for pound. At the same stage of maturity, grasses usually have a lower RFV than legumes because of higher NDF. However, lush leafy grass can exceed a RFV of 100, so don’t automatically consider grass hay less nutritious than legume hay. In most cases, the higher the RFV number, the better the quality of forage.

What To Look For When Buying Hay

According to what I mentioned above, when buying hay you should go for the highest relative feed value (RFV) you can find, right? Well, yes and no. How’s that for ambiguous?

I liken hay to gasoline: High priced, high-octane gas is better than low-octane gas if your car needs it, but not all cars need it. If your car doesn’t, you’re wasting your money. When Dolly and her six dozen clone sisters all look at you with their sad eyes, you’re going to be convinced they need the best stuff money can buy. Instead, treat your sheep like I treat my children, give them what they need and not what they want.

In the chart, you can see that the nutritional needs of an animal are dependant upon the age and how much “work” the animal is doing.

dollar alfalfa hay with 21% CP and 70% TDN for non-working rams is overkill and nothing more than a waste of money. Conversely, feeding weaned lambs August-baled tall fescue with 9% CP and 50% TDN is a sure-fire recipe for stunted, potbellied lambs.

Cheap hay is seldom a bargain. Even if someone gives you that fescue hay for free, it’s still very expensive forage for growing lambs. To meet their high nutritional needs, it will be necessary to supplement their diet with a lot of high priced grain concentrates.

Buying Hay: What to Expect Without a Forage Analysis

Don’t think all alfalfa is wonderful and all tall fescue is bad based upon the above example. All forage plants are much more nutritious when young and before seed formation begins than during and after seed has been set. The fescue mentioned above was probably 18% CP and 65% TDN in April and May before it headed out. Had the alfalfa not been baled until it was past full bloom, it could have easily been 13% CP and 50% TDN. If rained on, drop both those figures a couple more points. When hay is rained on before being harvested, nitrogen (thus protein) tends to be “washed” out, particularly legumes. Digestibility also goes down because the more soluble parts of the plant cell are washed out but the lignin and cellulose are unaffected. Legume hay normally has a greater nutrient loss when rained on than does grass hay because of a greater loss of the highly nutritious leaves.

Hay Species

The leaves of legumes (clover, alfalfa, lespedeza, trefoil) contain much more protein than do the stems. The leaves of full bloom alfalfa hay are three times as nutritious as the stem, so leafy hay is going to have higher protein than stemmy hay. First cutting (first crop of the season) alfalfa or clover hay tends to have a higher percentage of coarse stems than do subsequent cuttings and therefore tends to be lower in CP and TDN. Lespedeza is usually harvested only once a season but has fine stems regardless of age and is excellent sheep hay.

If you use the results of a legume hay analysis when formulating sheep rations you’re going to end up underestimating the nutritional content of the hay. Here is why: Forage tests require a sample of hay that is collected much like a soil sample. The core sample taken from the bale consists of stems, leaves, old growth, new growth and everything in between. The result of the test is an average of the sample. However, sheep seldom eat the entire bale and invariably leave stems. When feeding coarse, low protein legume hay, a sheep’s dexterous mouth allows it to pick out leaves while leaving the coarse stems behind. As a result, the actual diet of the animal is going to be much better than the test would lead you to believe. When formulating rations, the hay test results would have you overfeeding concentrates, which happen to be the highest priced feed source around. Sheep’s selective eating habits are advantageous nutritionally but financially, uneaten stems are wasted hay and wasted hay is wasted money.

In Summary

Do I run hay tests? No, I bale all my own hay and have a pretty good idea of what I’m feeding. If I bought all my hay, I’d probably want test results.

I mentioned alfalfa quite often and while I do bale some, I feed much more grass or grass-clover hay. You’re probably thinking what I do contradicts what I say and there may be some truth to that. However, a little common sense can do everything a $35 forage analysis will do.

Early in the hay feeding season when the weather is the warmest and the pregnant ewes’ nutritional needs the lowest, I feed my first cutting orchard grass or orchard grass-alfalfa hay. Because of weather constraints at harvest time, usually both the grass and alfalfa are entering the flowering stage and the ADF is going up and TDN down. As the pregnant ewes get bigger, their rumen space becomes limited. I then feed better quality hay such as second cutting grass or second or third cutting grass-legume which packs more “wallop” for its volume.

When a ewe’s nutritional needs are the highest (after lambing) I feed the best quality hay I have. Non-breeding rams get what I call “common” hay such as grass hay that was fully headed out or hay that had been rained on. Their needs are quite low and they will pick and choose enough to fully meet their needs.

Buying hay doesn’t have to be a game of “Russian Roulette.” Most hay producers are honest and truthful because they know unhappy customers don’t return. When buying shoes, knowing your foot size saves time and gets you in the right area from the start. Likewise, knowing your animal’s nutritional needs will help the seller provide you with what you need. Rare indeed is the hay producer that doesn’t have lower quality hay on hand at a reduced price, so don’t be afraid to ask for what you actually need. And besides, “speaking the language” will help keep honest people honest.

John Kirchhoff runs a low-input operation with 150 registered Katahdin ewes in north central Missouri. Eighteen years of selection, spare use of grain, hay and vets (but full use of rich and poor forages) lets him keep his extra-hardy, mid-sized ewes for only 28 to 30% of University of Missouri state average costs. Mr. Kirchhoff works full time with the local soil and water conservation district. Continually refining his own hands-on operation, he helps his clients avoid his mistakes and get reliably high returns.

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