By Dr. Alan S. Vaage Ph.D.

The greatest challenge for most producers when starting to use a TMR mixer is often understanding how to develop an appropriate ration, or mix, for their animals, and why feed analyses are such a key component of this process.
Animal performance is dictated by nutrient supply: The amounts of specific nutrients required to support a given animal’s body maintenance functions, reproduce, produce milk and/or grow are well known from decades of research, and are available in tabular form from a number of sources (e.g. National Research Council, “Nutrient Requirements of Beef Cattle,”  1996; online Extension Service publications; computer software). When combined with an estimate of dry matter intake, it is relatively easy to calculate the composition of the ration that is required to achieve a given level of performance. Failure to supply the minimum level of a given nutrient such as protein, energy, or a mineral, will generally restrict performance to the level dictated by that nutrient. Supplying an excess amount of a given nutrient (e.g. energy relative to protein) can cause excessive body weight gain or premature fattening, have a negative effect on reproduction, and generally wastes resources and unnecessarily increases feeding costs (especially energy, protein and phosphorus).
Limitations to traditional feeding methods: Traditional methods of feeding hay of unknown nutrient content, either to appetite or on an amount per head, perhaps with a given amount of grain, ensures that one or more nutrients will either limit performance or be fed in excess, and adversely affect profitability. Research has shown that changes in species composition, and the effects of weather and cutting on plant maturity and nutrient loss can cause forage nutrient composition to vary as much as 30 percent on the same farm, and for variation to be even greater across purchased forages.
Importance of regular feed analysis: Due to the annual variation in nutrient composition of most feedstuffs, average published or “book” values are generally unreliable for ration formulation, and it is generally recommended that all classes of feeds are sampled and analyzed for nutrient composition every year, especially forages, byproducts and whole grains. Analysis of protein supplements and other manufactured feeds should be available from suppliers.
Without feed analysis, one may be better formulating a ration based on what was fed on average in past years, and then make small adjustments to specific ingredients on an amount per head per day and observe the performance of the cattle over time, rather than relying on book values for formulation. Unfortunately, this is a lengthy and unreliable approach, which also makes it difficult to evaluate and incorporate alternative, potentially cost-effective ingredients. Only by having feeds analyzed is it possible to rapidly develop least-cost rations that are sure to meet the nutritional requirements of specific groups of animals. And, whether you do the work yourself, or have a nutritionist provide rations for you, it is useful to understand the basics of how feed analyses are used to formulate a TMR ration.
Basics of a feed analysis: Feed analyses are only as good as the quality of samples that are obtained. Bales of hay should be cored with an appropriate coring tool, silages should generally be sampled after fermentation from the face of the storage structure, and grains and byproducts can be sampled from the face of the pile in a commodity shed or as they are delivered from storage bins. In all cases, ideally about 10 representative cores and grab samples should be taken and composited to make one representative sample for each class of hay and/or type of feedstuff that will be fed. The samples should be placed in an airtight plastic bag (a “zip-loc” type freezer bag works well) and stored in a freezer until they are submitted to an accredited lab for analysis. For most beef operations, requesting a simple analysis by NIR (Near Infrared Spectroscopy) should be sufficient.
The specific analysis that is requested should contain at least the following items: Dry Matter (DM); Crude Protein (CP); three fiber components, Neutral Detergent Fiber (NDF), Acid Detergent Fiber (ADF) and Lignin; Fat; Ash; and the macro minerals Calcium (Ca) and Phosphorus (P), Magnesium (Mg), Sodium (Na) and Potassium (K). There will also be one or more estimates of energy content, such as Total Digestible Nutrients (TDN), Metabolizable Energy (ME), or Net Energy of Maintenance (NEm) or gain (NEg), and perhaps even Relative Feed Value (RFV). There is no analysis of energy per se; it is a calculation, an estimation based on one or more of the analyzed components given above. Each has its merits, and is used for formulating rations when energy requirements are expressed in the same way.
How to formulate a simple Total Mixed Ration: Once the requirements for the cattle have been defined, and the feeds have been analyzed, it’s a relatively simple process to develop a ration, as is illustrated in Table 1. The basic steps are as follows
1. For each ingredient:
a. The amount of an ingredient to be fed (Column D) is multiplied by its DM content (Column A) to get the amount of ingredient DM that is fed (Column E). Rations are formulated using dry matter as this is the fraction that contains the nutrients. It also defines the maximum amount of feed one can expect an animal to eat, a requirement which should not be exceeded when formulating rations; it thus controls how concentrated a ration needs to be to meet the nutritional requirements of a given class of animal.
b. For a given nutrient (e.g. Protein, Column B), the amount of ingredient dry matter to be fed is multiplied by its nutrients content on dry matter basis to get the amount that will be supplied from that ingredient (e.g. Column F for Protein).
2. The amounts of the nutrient supplied by each ingredient are summed together to give the total amount supplied in the whole ration or TMR.
3. These totals are then compared with the requirements to see how well they match.
Unless one uses a fairly sophisticated computer software program, ration formulation is essentially an iterative, or step-by-step process, of trying different formulations until one arrives at a suitable solution, especially when developing the first ration. Experience helps.

The following are some tips that may be useful:

1. Start with the forages. If there are more than one, set a ratio and increase the amount of mix fed, up to the maximum DM intake. Then determine if the energy requirement is met.
2. If the energy requirement if not met, add an energy source (grain and or byproduct) and remove forage until the energy requirement is met, without exceeding DM intake; it is acceptable if DM supplied is less than the recommended level as long as the animals are limit fed (i.e. not fed to appetite).
3. When energy is met, and if protein is low, add a protein source and remove grain and/or forage to balance depending on its energy content. It is acceptable for protein to be somewhat high as long as it comes from natural sources that also supply energy (e.g. distillers grains), but not from non-protein nitrogen sources such as urea.
4. Finally, when energy and protein requirements have been met, balance for specific minerals, especially calcium (Ca) and phosphorus (P) using mineral sources and adjust concentrates up and forages down to make room, as required.

Need some help?: Understanding the importance of feed analysis and basics of ration formulation enable a producer to get the most value out of their TMR mixer by more consistently achieving production goals and minimizing feed waste and feed cost by more efficient use of feed resources and appropriate use of least cost alternatives. Fortunately, it is not necessary to do this work by oneself to achieve the benefits; assistance with feed sampling and ration formulation should also be readily available from commercial feed suppliers, extension agents and private consultants in your area. Jaylor believes so strongly in the value of nutritional support for users of TMR mixers that is provides supplementary nutritional support to its customers and their nutritionists through its Nutrition Department — “Because Nutrition Matters.”™