Forage analysis important for your livestock enterprise!

Sandra Wick, Crop Production Agent

Well winter is certainly back!  We have been spoiled with some pretty mild conditions so far.  But, with the cold temperatures it is essential to know your forage analysis for your cattle.   Whether your cattle enterprise includes cow/calf, feeders or in feedlot operation, knowing your feed stuffs is the first component of balancing your ration. 

Dr. Justin Waggoner, K-State Research and Beef Systems specialist, shared some forage analysis guidelines in the December 2019 Extension Animal Science newsletter that I thought would be very useful for livestock producers.

You might be wondering just what numbers do I need in a forage analysis? One of the more common questions received with regard to analytical testing of forages and other feedstuffs is, “I have the sample, now what do I test for or what analysis package should I select?” The basic components that nutritionists need to evaluate a feedstuff or develop a ration are dry matter (DM) or moisture, crude protein (CP), an estimate of the energy content of the feedstuff (Total Digestible Nutrients (TDN), Net Energy for Maintenance (NEm), Net Energy for gain (NEg), and the macro minerals, Calcium and Phosphorous. These are the most basic numbers that are required, but including some additional analyses in the report can give us additional insight into the quality of the feedstuff or improve our ability to predict animal performance, which is the primary reason we analyze feedstuffs. 

Other components that the report might include is acid detergent fiber (ADF) and neutral detergent fiber (NDF). The amount of NDF in forage reflects the amount of cell wall contents (hemicellulose, cellulose, and lignin) within the sample. The NDF fraction is often associated with the respective bulkiness of forage and is correlated with dry matter intake of the forage or feedstuff. Therefore, the amount of NDF may be used to estimate the expected dry matter intake associated with the forage.

The ADF number represents the amount of cellulose and lignin within the forage and is correlated with the respective digestibility of the forage. In general, a higher ADF value is associated with forage that has a greater proportion of cellulose and lignin and would likely be more mature. Additionally, the ADF fraction is used to calculate the energy estimates TDN, NEm, and NEg that appear on the report.

There are a number of different mathematical equations that the testing laboratory may use to calculate these numbers, based on the type of sample (corn silage, alfalfa, grass hay, etc.). If the ADF is included in the report, the nutritionist can adjust or recalculate the energy estimates if necessary.

If the forage will be fed in combination with a byproduct feed, such as wet distiller’s grain, including an analysis for sulfur can be beneficial if the forage will be used in a growing or feedlot ration. Additionally, if the forage is a known nitrate accumulator (forage sorghums, sudangrass) or may have been stressed due to drought, including a nitrate analysis should always be considered, especially if the forage will be fed to pregnant cows.  

          

Most analytical laboratories have a number of different analysis packages which encompass the most common procedures or numbers that a nutritionist or producer needs to know about their feeds. These packages will typically include the basic procedures (DM, CP, TDN) and then add on specific analyses such as NDF or the Macro-minerals (Ca, P, Mg, K, Na, Cl, S). Some laboratories may group analysis packages by the type of sample (Forage vs. mixed ration) or production purposes (dairy vs. beef).

         

The objective of analytical testing of forages and feedstuffs is to improve our ability to meet the animal’s nutrient requirements and ultimately predict animal performance. The best method of evaluating the quality of a feedstuff is feeding the feedstuff to an animal and evaluating performance over a set period of time, under a specific set of conditions. Since that would not be cost effective or timely, analytically evaluating feedstuffs in a laboratory is the next best thing and although it is not perfect, it is better than the “this looks like really good stuff” method of evaluating feedstuffs.

If you have any questions regarding forage analysis, contact me at any of our Post Rock Extension District Offices in Beloit, Lincoln, Mankato, Osborne or Smith Center.

Post Rock Extension District of K-State Research and Extension serves Jewell, Lincoln, Mitchell, Osborne, and Smith counties. Sandra may be contacted at swick@ksu.edu  or by calling Smith Center, 282-6823, Beloit 738-3597, Lincoln 524-4432, Mankato 378-3174, or Osborne 346-2521.  Join us on Facebook at “Post Rock Extension” along with our blog site at “postrockextension.blogspot.com.  Also remember our website is www.postrock.ksu.edu and my twitter account is @PRDcrops.