All feeds are composed of two parts, dry matter (DM) and water. The DM portion of feed is composed of protein, fat, carbohydrates, vitamins and minerals, essentially any nutrient that can be quantified. The amount of water (i.e. moisture) present in a feed is highly variable. To remove the variation, we formulate all rations on a DM basis, which means having accurate DM’s on your feed ingredients is very important. This is a key concept in ruminant nutrition and is in contrast to feed formulations that are done for swine, poultry, aquatics, and other species where animals consume a physically consistent ration, the variation in ingredient DM is very small, and the resulting impacts of varying feed DM are relatively minor.
For example, if we formulated a ration for you that targeted 20 lbs. corn silage on a DM basis but the dry matter of the silage used in our formulation was off by 10 percentage points, that would throw off the pounds of silage the cattle were getting (Table 1). This means the ration is no longer balanced the way we had intended and we are either over or under feeding an ingredient which is impacting the price of the ration.
Having accurate DM’s also influences the price of your ingredients. For example, let’s look at a price comparison of modified distillers grains (MDG) at two different DM’s. Let’s say you can get MDG for $110/ton (as-fed basis). The guaranteed DM on the distillers is 46%, which means the MDG is $239/ton (DM basis). If that DM was 40% instead of 46%, then the MDG is actually $275/ton (DM basis). That is a $36/ton difference in cost on a DM basis. To put that on a bushel basis, that $36/ton difference is like paying an additional $1.00 per bushel.
For these reasons, we recommend testing dry matters on ensiled feeds and wet grain processing by-products often to ensure we are formulating your rations correctly. While ensiled feeds and wet grain processing by-products by their nature are the most prone to DM variation, other dry grains, forages, and food/bakery waste products can vary significantly as well. Dry hays can easily vary by as much as 15-20 percentage points and often contain more moisture than one assumes. Likewise, pelleted feeds if stored outside can attract and retain moisture well beyond their original amount. Commodity sheds pay for themselves by protecting feedstuffs and therefore reducing shrink.
There are a multitude of ways to test the dry matter on your feeds. The first and likely easiest method is to have a GPLC consultant or field representative come out and pull feed samples for you. The typical analysis package we have conducted on feeds is relatively inexpensive ($18 per sample) for the information it provides. If the full nutrient profile is not needed, a sample can be submitted for just DM analysis.
Another option is conducting a microwave dry matter test at home. You should never leave a feed sam-ple drying in the microwave unattended because the feed sample could catch on fire if the sample is not stirred frequently. In addition, you may want to purchase your wife flowers (or a new microwave) if you plan on using the microwave to dry feeds because there is typically a residual smell and/or mess. However, it is a relatively rapid and convenient method to determine DM which can be helpful in situations when DM needs to be measured immediately and one cannot wait 1-3 days for lab results.
The third option is conducting a koster tester dry matter. This method would require the purchase of a koster drying system which would cost you approximately $450 if you purchase the system and scale (https://buykoster.com/shop). If you are looking to test the dry matter of a feed with a small particle size, make sure to check and see if the feed will sit in the drying pan without falling through, otherwise you will lose sample and have an inaccurate DM.
We only went over a few methods for testing dry matter on your feeds in this article. There are more, however, these options are likely the most economical and practical methods to use on farm without spending a substantial amount of money on equipment. The protocols for both the microwave and koster tester dry matters can be found on our website (https://www.gplc-inc.com/formuladocuments/). Regardless of how feed ingredient DM values are determined, it is simple for our team to modify rations and batch sheets for our clients with correct moisture levels to ensure rations are fed correctly. Many digital feeding management programs today allow for feed DM values to be easily changed so that the as-fed values change accordingly while the percent DM composition/inclusion of the ration remains constant, thus nutrients supplied to the animal remains constant as well. As always, do not hesitate to reach out to one of our consultants if you have any questions regarding the dry matter content of your feeds!
For assistance with this or other nutrition-related matters, contact Great Plains Livestock Consulting at GPLC-Inc.com