What is Dry Matter and Why is it Important?

Knowing the dry matter concentration of any wet feed is something every producer should know.

Determining the dry matter concentration of wet forages is one of the most basic, and arguably the most important things to measure in wet forages and can be easily done on the farm. The Benefit to measuring the dry matter concentration on farm is that it is quicker than sending it to a lab, and the quicker the ration is adjusted to the new dry matter concentration the more accurate the ration.

Once the dry matter is determined, the ration needs to reflect any changes in the value. For example, if corn silage dry matter changes from 35% dry matter one week to 30% dry matter the next week, but the ration is not adjusted to reflect that change, crude protein concentration of the diet will increase from 15.8% to 16.3%. In this example, the cow will be getting more protein and nitrogen than she needs, and the excess nitrogen will end up in the urine potentially leading to air and water pollution.

Excess nitrogen and phosphorus are major contributors to water quality concerns of the Chesapeake Bay. Conversely, if the dry matter of the corn silage increased from 30% to 35% and the ration is not adjusted the cows will be getting less energy and protein than they should be because increasing the corn silage will dilute out the rest of the ration. This could lead to a decrease in milk production, which is never a good thing.

Formulating rations to the cow’s requirement and then mixing that ration as close as possible to what is on paper is necessary in order to reduce nutrient losses to the environment and maintain a consistent high level of production. This becomes very difficult to do when the dry matter of a large portion of the ration is not known accurately. So get out there and start weekly testing of your feeds!