Dry Matter Protein Calculator
Convert as-fed crude protein into dry matter protein, compare two feeds side by side, and estimate the supplement needed to close a protein gap.
Protein labels and forage tests are often reported as-fed, while ration targets are usually judged on dry matter. This calculator keeps the water weight visible so a wet feed and a dry feed can be compared fairly.
Dry matter protein report
Alfalfa hay protein converted from as-fed to dry matter basis.
| Protein step | Formula | Example | What it tells you |
|---|---|---|---|
| Dry matter percent | 100 - moisture percent | 12% moisture gives 88% DM | How much of the feed is not water. |
| Protein on DM basis | As-fed CP / DM fraction | 16 / 0.88 = 18.2% CP | Fair comparison between wet and dry feeds. |
| Protein supplied | As-fed amount x as-fed CP percent | 20 lb x 16% = 3.2 lb | Daily crude protein delivered by scale weight. |
| Target protein mass | Feed DM x target CP percent | 17.6 lb DM x 12% = 2.11 lb | Protein needed for that dry matter amount. |
| Supplement as-fed | Gap / supplement as-fed CP | 0.5 / (48% x 89%) | Amount of supplement to close a gap. |
| Feed or ingredient | Typical moisture | Typical CP on DM | Protein note |
|---|---|---|---|
| Grass hay | 8% to 14% | 7% to 14% | Maturity can change protein more than species name. |
| Alfalfa hay | 8% to 15% | 15% to 24% | Leaf retention and cutting stage matter. |
| Corn silage | 60% to 70% | 7% to 9% | As-fed protein looks very low because it is wet. |
| Soybean meal | 10% to 12% | 44% to 50% | High protein supplement for livestock rations. |
| Dry dog kibble | 8% to 12% | 20% to 35% | Convert guaranteed analysis to compare with wet food. |
| Canned pet food | 72% to 82% | 25% to 55% | Low as-fed protein can become high on dry matter. |
| Livestock use | Common target CP on DM | Moisture concern | Field check |
|---|---|---|---|
| Dry beef cow maintenance | 7% to 9% | Weathered hay can test lower than expected. | Watch body condition and manure consistency. |
| Lactating beef cow | 10% to 12% | Low protein hay can limit milk and intake. | Test hay before choosing supplement. |
| Growing calves | 12% to 16% | Wet feeds dilute pounds in the bunk. | Track gain and bunk refusals. |
| Lactating dairy cow | 15% to 18% | TMR moisture swings change dry matter intake. | Recheck silage DM often. |
| Ewes or does late gestation | 11% to 14% | Forage quality affects supplement need. | Balance protein with energy and minerals. |
| Pet food comparison | As-fed label | Moisture | Dry matter protein |
|---|---|---|---|
| Dry kibble | 24% protein | 10% | 26.7% protein on DM basis |
| Canned dog food | 8% protein | 78% | 36.4% protein on DM basis |
| Canned cat food | 10% protein | 78% | 45.5% protein on DM basis |
| Semi-moist treat | 14% protein | 28% | 19.4% protein on DM basis |
| Freeze dried topper | 40% protein | 5% | 42.1% protein on DM basis |
For forages: Use actual lab moisture and crude protein whenever possible. Hay from the same field can shift after rain, curing losses, heating, storage, and cutting date.
For pet food: Guaranteed analysis values are usually as-fed minimums. Dry matter comparison helps compare wet cans, pouches, kibble, and toppers without letting water hide the protein density.
Feed and forage test results can include protein numbers on the label. However, the protein numbers on feed and forage labels is usually based off the as-fed feed. The as-fed number of protein include the weight of the water in the feed.
Forage test results in as-fed numbers includes the water content in the forage. Because the as-fed protein number include the water in the forage, the protein value of the as-fed forage may appear lower then the actual protein content of the forage. For example, if the forage is very wet, the protein number may be lower on the label than the forage actually contributes to the animal’s protein intake when the water is removed from the equation.
Why Convert Feed Protein to Dry Matter
Moisture in forage impact how much actual forage is delivered to the animal. Forage labels will often include the moisture percentage of the forage. For instance, 20 pound of alfalfa at 12% moisture contains less alfalfa than 20 pounds of alfalfa at 10% moisture because the alfalfa at 10% moisture contains more water.
The same weight of alfalfa at 12% and alfalfa at 65% moisture will supply different amount of protein, energy, and fiber to the animal because of the moisture content of each type of forage. Nutritionists use the dry matter basis to account for moisture content in the forage when making comparison between different types of forage supplements. A dry matter basis removes the moisture content from the forage test results so that the reader can see the actual composition of the forage.
The calculator included after this article will help to convert the as-fed protein percentage of the forage to a dry matter basis protein percentage, as well as to show the total daily protein provided by the forage in pounds or grams. The calculator also provide a side-by-side comparison between two different types of forage and will calculate the amount of supplement feed need to close the gap between protein content of the forage being fed and the protein needs of the animal. These four results help to convert the protein percentages from confusing numbers to easy-to-understand decisions.
Outside of the forage being tested, there are other variables that can impact the protein percentage of the forage. For instance, hay that is exposed to rain may test with a lower percentage of protein than hay that is harvested during a dry week. Silage that is packed loose will contain more moisture than silage that is packed in a sealed bag.
Additionally, canned pet food can contain 75 to 80% water. A can of pet food that lists 8% protein on an as-fed basis may have a dry matter protein value of 30% which is competitive with dry diets. The same logic can be applied to choosing a supplement.
Soybean meal, for instance, may list 48% protein on a dry matter basis. However, because the soybean meal on the supplement feed bag contains a small amount of moisture, the protein percentage on the bag will be slightly less then 48%. Comparing the as-fed protein of soybean supplement to 16% as-fed alfalfa without converting to a dry matter basis may make it look like the soybean supplement is stronger than it is when compared to the alfalfa.
However, using the supplement calculator will ensure that both the supplement and the forage is on the same footing for comparison. The protein requirements of livestock change with the stage of production of the animal. For example, dry beef cows in maintenance require 7 to 9% protein on a dry matter basis.
However, lactating dairy cows require 15 to 18% protein on a dry matter basis. Because the protein requirement of livestock is provided on a dry matter basis, the same hay can meet the protein needs of a dry cow but not provide enough protein for a milking cow. The supplement gap calculator will show the protein gap between the protein supplied by the forage and the protein required by the animal.
Additionally, the supplement gap calculator will provide the answer in the amount of pounds or grams of supplement that should be bought and fed to the livestock to fill the protein gap. Finally, the same apply to feeding pets dry kibble and canned food. The bag of dry kibble may say it contains 24% protein.
However, a can of canned food may contain only 8% protein on an as-fed basis. However, when those percentages are converted to a dry matter basis, the canned food may provide more protein per pound of food then the dry kibble. This is one reason why animals on a canned diet may maintain better muscle mass than those on a dry kibble diet alone.
The most important of the calculations described will be determining whether the protein percentage listed for a feed or forage is on an as-fed or dry matter basis. If the protein percentage is on an as-fed basis, that percentage must be converted to a dry matter basis before buying any supplement or altering the rationing of the forage to the livestock. The calculator included will make it easier for the livestock manager to determine whether the forage or supplement meet the protein needs of the animal in question.
