By Rick Kleyn, SPESFEED (Pty) Ltd.

Feed formulation is the means by which commercial nutritionists apply both their technical and commercial skills in practice. Although formulation is a science rather than an art form, more experienced formulators who have developed “gut feel’ tend to be more effective. By employing the correct formulation skills and techniques the nutritionist can bring about cost savings and/or improvements in animal performance. These two aspects can make huge differences to the overall profitability of both milling companies and integrators.

Although the objectives of feed formulation for feed millers and integrators may differ, with the former being more concerned about maintaining product quality at as low a cost as possible and the latter being concerned with maximizing profit in the animal production enterprise, the same basic principles apply. The nutritionist needs to carefully consider what she/he is currently doing with regards formulation techniques, the ingredients used, matrix values and feed specifications.

This article will consider some general thoughts on feed formulation and will then deal with some formulation techniques. It covers some of the more commercial aspects of ingredient usage and will highlight some of the nutritional aspects that should be considered. The complete formulator needs to have competences in each of these areas.

General Aspects:

New perspectives: Firman (2003), points out that many nutritionists are relatively speaking, self-taught with regards feed formulation. It is simply not possible for Universities and Colleges to provide the kind of experience that a commercial formulator requires. Experience usually takes a number of years and many hundreds of formulations to achieve. However, it is possible to have 5 years experience, (one year 5 times over) and never be exposed to other ideas. As a result it is easy for a formulator to get in a rut and not look at other ways of doing things. A new perspective is always valuable. Concerns about the sensitivity of a company’s data (secrecy) often prevent any meaningful exchange of ideas from taking place. In reality there are few secrets in our industry, only different perspectives on similar problems. Interaction is essential.

Administration: In an age where the paper trial and traceability have become all important, it is essential that the formulator has the correct tools, both electronic or otherwise, to maintain full traceability of all that she/he does.

Keep it simple: It is true that modern feed formulation systems allow the nutritionist to use an almost limitless number of nutrient constraints. It is also possible to constrain nutrients in terms of ratios, use them to constrain groups of ingredients or in some cases to use them as a non- nutritional (dummy) variable. However, all of these additional constraints can and do cost money. In addition, is it sometimes difficult to understand exactly why a formulation has become infeasible or how much money a constraint (a ratio for example) costs. From a practical perspective, large numbers of constraints make it is almost impossible to check matrix values and indeed even formulations meaningfully.

Regular revision: When things are going well we tend to forget to reevaluate our formulations. They may not need to be changed, but a regular evaluation of ingredient costs, ingredient quality and ultimate animal performance is always a good idea. Always use your most experienced nutritionists to double check the work of the formulator. Feed formulation is an interactive process, and I do not believe that it is possible to re-evaluate your formulations simply by making use of a printed report. It is essential that the more experienced individuals get their hands dirty and actually spend time on the formulation system.

Check all formulations: It is tempting to assume that computer generated formulations are correct. Nothing could be further from the truth. A formulation may well meet its nutritional constraints, but may be completely wrong from a cost perspective. More dangerously, it may well exceed a set constraint by several fold. All formulations should be checked, either by some form of intelligent software, such as Format International’s Biosecurity® module, and/or by hand. Make sure that each formulation conforms in the following manner:

  • Compare the current cost with that of the previous formulation. A huge variation often indicates a problem with the formulation.
  • Ensure that all nutrients fall within with normal nutrient tolerances. Often a nutrient that has been over included indicates a problem elsewhere.
  • Ensure that no harmful ingredients have been included, such as urea in a pig or poultry diet.
  • Ensure that premix and medication inclusion is correct.Feed Formulation Technique:Use a limited number of constraints: Nutrient and ingredient constraints are part of the formulation process. Each limiting constraint leads to an increase in the cost of the diet. Constraints can always be added back after we have seen the effects that they have on cost.Examine sensitivity data: Those nutrient constraints that are “costing” a lot in a formulation will always have a high reduced cost or sensitivity. In most cases the nutritionist would not want to change these as any change would be construed as “stealing out of the bag”. However, there are instances when a redundant maximum constraint – for example, crude fibre in a broiler diet, can result in a significant increase in cost. Bearing in mind the high variability in fibre determination, we need to make sure that using a fibre maximum is really justified.Remove redundant constraints: The nutritionist should always be sure to remove any redundant constraints. For example, if you are formulating diets on a digestible amino acid basis, be sure to remove any total amino acid constraints – these will only cost you money without improving animal performance.

    Safety margins: Safety margins are a commonly used method of ensuring that all nutrient requirements are being met. They are ways of overcoming the variation in nutrient levels through a variety of mostly uncontrolled factors. By reducing the variability of ingredients (buying from a single source for example) or accurately monitoring incoming ingredient quality, they can be reduced or eliminated. Variability can be further reduced by accurate weighing and batching and complete mixing.

    Look for pressure points: When an ingredient or nutrient bumps up against a constraint there is often a reason. This may well have to do with the specification of the diet itself, but equally could be caused by an error in the matrix. Check your matrix for those nutrients that are limiting and make sure that the values used are within normal tolerances.


Use all Ingredients: The most important concept of formulation is that we supply our animals with nutrients, rather than on an ingredients basis. Ingredients should be viewed as a means of providing digestible nutrients at the correct levels. Always start the formulation process with as many ingredient choices as possible. This would include unusual bi-products, purified ingredients such as amino acids and any other alternatives available. Remember though that additional ingredients complicate mill management and have a way of increasing the working capital requirements. Dealing with unusual ingredients does present challenges in that the exact nutrient composition of the ingredient is often unknown. If this is the case, it is perhaps better not to use it.

Ingredients must conform: A diet is only as good as the ingredients used in its manufacture. All of our ingredients must conform to the quality parameters set – in short, know your ingredients. These would include nutrient content and variability, the physical form of the ingredient and its biological quality. Know the origin of your ingredients! You need to know not just the country, but the factory of origin as well. Poor quality ingredients are probably the single biggest cause of feed related losses.

Use the correct prices when formulating: Although open to debate, it is always good practice to formulate your diets using the “replacement” costs of different ingredients. There is a simple reason for doing this. If, for example, the price of an ingredient suddenly increases, it is a) likely that the ingredient is in short supply and b) the value of any stock that you are carrying is worth significantly more than it was previously. If you formulate at a lower price, you run the danger of over using what is in effect a scarce and expensive resource. Obviously, exactly the opposite will apply when the price of an ingredient softens dramatically.

Use the correct ingredients in the correct diets: Under commercial conditions, ingredients may be in short supply, or very expensive which is much the same thing. The nutritionist therefore needs to decide where best to use restricted ingredients. For example, if Full Fat Soybean supplies are limited, it makes little sense to use it in Broiler Starter or Layer diets – rather use it in high density Broiler Grower and Finisher diets. The use of Multi-Mix® techniques eliminates the guesswork from this particular aspect. It allows for the optimization of an entire range of diets, simultaneously considering their relative volumes together with ingredient availability and cost. Use of Multi-Mix® technology gives the feed miller an overall picture of the business and allows for meaningful ingredient purchasing strategies to be developed. Experience has shown that the use of Multi-Mix® will reduce overall feed costs by 2 to 3%.

Make use of ranging data: Modern feed formulation programs will mostly show a “Range” of ingredient costs between which the formulation will not change. The nutritionist can use this information for both buying and formulation decisions. The use of some form of parametric evaluation may be useful in this instance. Parametric evaluation is a technique whereby a number of formulations to be carried out over a range of prices. It is possible to draw step supply curves with this information to better understand the impact that changing cost will have not only on an individual diet, but also the whole feed milling operation.

Use enough premixes: For logistical reasons we are often tempted to use a limited range of premixes. Ideally, we should use different premixes for every diet, so realizing significant savings. For example, we tend to use a Broiler Grower premix in Broiler Finisher diets as a routine practice. This practice has no nutritional basis and is an expensive practice.

Nutritional Aspects:

There are a number of techniques that fall under the heading – Use the Correct Feed Specifications. This is a huge topic and will only be dealt with briefly. In practical terms, nutritionists are often faced with a dilemma of choosing which diets to feed. The breeding companies (who supply the genotypes that we use) publish values but they make little allowance for maximizing returns or for local conditions. Other sources would include recent scientific literature and old standards such as the NRC (1994). Mostly, these are of little help, because nutritionists are either interested in the level of animal performance that will lead to maximum profit, or in formulating diets that will allow their companies to compete in the market place. All decisions regarding feed specifications need to be made bearing these two aspects in mind.

Evaluate and use feed additives carefully: There are a wide range of feed additives on the market. Although they may not always show the type of response that nutritionists like to see, or represent good value for money, ignore them at your peril. A good example of a “new” additive is phytase. This is an ingredient that has allowed for a reduction of the phosphorus levels in our diets at considerable cost saving. As a rule of thumb – for every Euro spent on an additive, expect a two Euro return.

Use meaningful nutrients: Costs can be reduced by using the appropriate nutrient profiles when formulating. Formulating diets using digestible amino acid constraints is now widely practiced. This saves money and makes using alternative ingredients easier and more predictable in terms of animal performance. It also enables us to more accurately determine and meet the animals’ nutrient requirements. The use of more advanced energy systems, such as the Net Energy system for pigs will lead to additional savings.

Use enough diets: Using the correct number of phases allows us to meet the animals’ changing requirement for nutrients as they age. In broad terms phase feeding eliminates the over and undersupply of protein and energy during the different life stages. Increasing the number of phases leads to reduced feeding costs and improved animal performance. However, the greater the number of different diets used on a farm, the more difficult management becomes, with an increased likelihood of making mistakes.

Use the correct nutrient density: Diets that contain a high nutrient density (high in energy and amino acids) often result in the best growth and technical performance. However, these diets may not always result in the most profitable production systems. It is therefore essential to consider the value of enhanced performance relative to the cost of the diet. The optimum nutrient density is circumstance unique and should thus be determined for each production system.

Reduce crude protein constraints: The NRC protein constraint for a Turkey Starter ration is 28%. This can be safely reduced by several percentage units. The same can be shown in the case of laying hens. Do not to reduce the protein specification of broiler diets too much as current research shows that there is a finite requirement for protein relative to lysine (amino acid).

Examine Calcium and Phosphorus levels: From a nutritional perspective, Ca and P are regarded together. There is increasing pressure to reduce the levels of P in animal waste: as a result of which there is a large amount of research currently being carried out in this regard. From this, it would appear that for most monogastric animals the levels of P that are currently being used in our diets are too high. There are sound reasons for reducing P and Ca levels in all of our diets. However, the latest data being published by the breeding companies is at odds with these findings, with most companies increasing their recommendations for Ca and P. This particular aspect has become even more relevant in the light of the rocketing costs of feed phosphate.

Bio-Security® and Multi-Mix® are supplied by Format International (

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