DETERMINING LEAST-COST FEED

Determining the least-cost feed is one of the most beneficial ways to decrease feeding costs. To determine the least-cost feedstuff, the costs of the major ingredient of concern in each feed should be compared. The major ingredient of concern is either the ingredient present in the greatest amount in that feedstuff, or the reason a particular feed is being fed. For a protein supplement, this would be protein. For a mineral mix, it might be either calcium or phosphorus. However, since the cost of phosphorus is routinely much greater than the cost of calcium, phosphorus is the major ingredient of economic concern in most calcium-phosphorus-containing mineral supplements. For all cereal grains, grain mixes and sweet feeds, fats, and oils, and generally for hay, haylage, or ensilage, the major ingredient of concern is energy, since as a source of energy is the major reason they need to be or are fed.

A nutrient in a feed that is not needed by the animal adds no value to the feed and, therefore, should not be taken into consideration. For example, if a horse needs 8% protein in its diet and a hay containing 8% or more protein is being fed, the protein content of the grain fed is of no concern—i.e., a grain mix containing 16% protein is of no greater benefit than one containing 8% protein. Thus, in this example the only nutrient that should be considered in the grain is its energy content.

To determine the cost of the major nutrient of concern in a feedstuff, divide the cost of the feed by the fraction of that nutrient in the feed, as shown in the following examples. It is important that comparisons be made among feeds equal in moisture content. To ensure that this is done, it is best to convert either the cost of the feed or the amount of nutrients in the feed to the amount present in the feed dry matter. How this is done and obtaining the amount of nutrients in the feed are described in the section on “Nutrient Content of Feeds” in Chapter 6.

Example 1—Determining the Least-Cost Hay Considering One Nutrient. Determine which of the following two hays is more economical to feed.

Since both hays contain enough protein, calcium, and phosphorus to meet the horse’s requirements, the differences in the amount of these nutrients in the two hays need not be taken into consideration. The only nutrient of concern economically in the hays is the energy they will provide, so we compare their cost on an energy basis as shown.

Although the grass costs less per ton of hay, because of its lower energy content it costs more per calorie of digestible energy; therefore, the alfalfa is a better buy.

To further demonstrate this, calculate the cost of feeding both hays. In calculating which feed costs the least if the previous procedure is conducted, the procedure given below is not necessary but is done here to emphasize that the answer obtained using the previous procedure is correct and to demonstrate how to determine the feeding cost difference. The idle 1100-lb (500-kg) horse needs 16.4 Meal DE/day (Appendix Table 4). The amount of each hay needed to provide this, and the associated cost, would be:

Example 2—Determining the Least-Cost Protein Supplement. Determine which of the following protein supplements is the least expensive.

The reason these supplements will be used is as a source of protein. To find the one that provides protein most economically, determine the cost of protein from each by dividing the cost of the supplement by its usable protein content. For Range Cubes A, this would be 39 – 13, or 26% protein, not 39%, since the horse utilizes little nonprotein nitrogen such as urea. Thus, as shown above, Range Cubes B provide the least-expensive source of protein. If the supplement was to be used for mature horses, its source of protein doesn’t matter, i.e., whether it contained soybean meal, cottonseed meal, or any other source of protein.

As shown here, and as is routinely the case, phosphorus is much more expensive than calcium. Calcium is quite inexpensive. If in this example additional phosphorus, but not calcium, is needed in the diet, monophos would be the most economical supplement to use. The calcium provided by the dical is not needed and, therefore, is of no benefit. It also is of no harm unless it results in a calcium: phosphorus ratio in the total diet outside of the acceptable range (as given in Chapter 2). However, if both calcium and phosphorus are needed, the value of both must be considered. To do this, first determine the amount of monophos and limestone needed to provide the same amount of calcium and phosphorus as provided by the dical, which in the example as given in the table is 24 lbs Ca and 19 lbs P/100 lbs of dical.

Next, determine the cost for the amount of each mineral mix needed to provide the same amount of calcium and phosphorus as 100 lbs of dical. The cost for the limestone plus monophos mixture is:

Thus, if both calcium and phosphorus were needed, in this example dical would be the most economical mineral supplement to use.

Example 4—Determining the Least-Cost Hay Considering Two Nutrients. Determine which of the following two types of hay is the least expensive for feeding weanlings.

However, if the supplement was to be used for growing horses, you should ensure that the supplement’s protein contains 5% or more of the essential amino acid lysine (Table 4-7 gives this information).

Example 3—Determining the Least-Cost Mineral Supplement. If the following mineral mixes are available, which is the least expensive?

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