WW-00469 Reviewed 2008
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Most dairy producers buy some feed. It may be a complete grain mix, protein supplement, urea-molasses liquid, mineral supplement, vitamin mix or feed additive. However, some dairy producers do not know what they are buying. Is it worth $10 or $15 per hundred? What will it do? A feed tag can give clues to these and other questions.
Protein. Protein is one nutrient that should receive close attention. The sample feed tag (figure 8) guarantees a minimum of 36 percent crude protein equivalent or 36 pounds of crude protein per 100 pounds of feed. If a source of NPN (urea, ammonium salt, etc.) is used, it will be listed below the crude protein level as "percent equivalent crude protein from nonprotein nitrogen (NPN)."
Many commercial protein supplements contain some NPN, usually as urea. The amount of crude protein equivalent supplied by NPN is listed on the tag. For example, supplement XYZ contains 36 percent crude protein, of which 11.2 percent crude protein is supplied by NPN. This means that 100 pounds of supplement contains 36 pounds of crude protein, of which 11.2 pounds of crude protein is supplied by NPN. The percent of urea in the supplement may be calculated as follows:
11.2 x 100
*Divided by 287 because urea contains 46 percent nitrogen.
Protein contains 16 percent nitrogen.
Thus, 6.25 x 46 percent nitrogen = 287 lb of crude protein
equivalent in 100 lb of urea.
If high producing cows are fed 4 pounds of this commercial supplement daily, the cow consumes 0.16 pound of urea. This is a safe level of urea feeding (3.9% x 4 lb = 0.16 lb/cow/day).
Fat. Fats and oils contain 2.25 times more energy than the same weight of starch or sugar (carbohydrates). Fats increase palatability and prevent dustiness. Most grain mixes contain less than 5 percent and protein supplements less than 10 percent fat. The total ration should not contain more than 7 percent fat from all sources.
Animal and/or vegetable fat can be used by the dairy cow. Milk production and/or fat test must increase to pay for added fat. High-producing cows that cannot consume enough grain may respond economically to added fat. Fat test may increase or decrease depending on the type of fat and method fed.
Crude fiber. Crude fiber is a critical component. Since most feed tags do not list an energy value (no practical way to measure accurately), the guaranteed fiber level gives a hint.
As fiber level increases, energy level usually declines. Generally, for each 1 percent rise in fiber, TDN level drops about 1 percent. Fiber levels should be checked, especially in pelleted or complete dairy mixes (table 16).
Minerals and vitamins. Other guaranteed nutrients, such as minerals and vitamins, should be considered when looking at a feed tag. If the feed is bought primarily for phosphorus or vitamins, calculate cost per pound or unit of that nutrient.
Feed ingredients used in making the mixture are listed below the guaranteed analysis. The percent or amount of each ingredient does not appear, but generally ingredients are listed in a descending order of amounts used in making the feed. Different amounts can be used as long as the guaranteed levels of nutrients are met. For example, one batch of feed could contain wheat bran this week and wheat midds next week. This can affect palatability and intake, but is not a problem with reputable feed companies.
Collective terms. There may be collective terms on feed tags. The various groups with some examples of feeds in each group follow:
If individual ingredients are named on the label, there is sometimes an "and/or" designation. This allows alternative ingredients for registration purposes (example: soybean meal and/or linseed meal).
Many feeds contain ingredients that are not nutrients, but function in other ways. Table 17 lists common additives, their functions, and current recommendations.
A comparative dollar value of some common feedstuffs can be obtained by using the factors in table A-16. The feed evaluation factors consider energy and protein from corn and soybean meal for all feeds and fiber from alfalfa hay for forages. To obtain an estimated dollar value of a feed on the list:
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