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Simple concepts at the basis of pig feed formulation

It is not enough to have a feed formulation computer program and someone to operate it. It is not enough even to have the latest feed specification figures and the most updated ingredient nutrient matrix. All these are a prerequisite to having someone experienced enough to put everything together if a wholesome, healthy and profitable feed is to be mixed, manufactured, transported, stored and eventually fed to animals.

feed-formulation-nutritionists

It is not enough to have a feed formulation computer program and someone to operate it. It is not enough even to have the latest feed specification figures and the most updated ingredient nutrient matrix. All these are a prerequisite to having someone experienced enough to put everything together if a wholesome, healthy and profitable feed is to be mixed, manufactured, transported, stored and eventually fed to animals.

At each step, there are problems that can be avoided or ameliorated through initial feed formulation. That is why long experience is required to be paired with deep knowledge not to produce a least-cost formula, but rather a commercial feed with a purpose. Below is a brief summary of the main points that must be attended to ensure feed is formulated based on the most modern and economic ways.

Energy

Worldwide, most feeds are formulated using the metabolizable energy (ME) system, having long abandoned the digestible energy (DE) system. While this is a perfectly good system, it suffers severely when formulas depart from common energy (corn, wheat) and protein sources (soybean meal).

The reason is simple: with the ME system, byproducts rich in fiber or protein are not evaluated correctly. This issue is then resolved by the net energy (NE) system.

energy-concentration-pig-feed

The conversion of metabolizable energy to net energy is similar when it comes to common cereals, such as corn and wheat, and thus it makes little difference which system is used in formulating feeds based on these ingredients. When it comes to less conventional ingredients, however, the disparity is very large.

It is obvious that the conversion of ME to NE is similar when it comes to common cereals, such as corn and wheat, and thus it makes little difference which system is used in formulating feeds based on these ingredients. When it comes to less conventional ingredients, however, the disparity is very large.

Another benefit of the NE system is that it allows for separate energy values to be used in growing pigs versus breeding animals (sows and boars). The ME system ignores the energy contribution from fermentation taking place in the large intestine, but the NE system correctly attributes a better NE value when ingredients are destined for use in breeding animals. In other words, feeds for sows formulated on NE tend to be less expensive.

Protein

Protein and, consequently, amino acids are the second most expensive nutrients in a pig feed, after energy. Therefore, using the correct form to describe their presence in feed is of paramount importance in creating a least-cost formula.

When using total amino acids, a minimum in crude protein concentration is required to ensure all amino acids are present in sufficient quantities. However, by using digestible amino acids, formulas do not have to have a protein minimum, assuming all essential amino acids are sufficiently covered through formulation monitoring. This translates again in feed formulated at the least possible cost, taking into advantage cheaper sources of protein, and quite often feed-grade amino acids.

That there is a plethora of published values for digestible amino acids, some of which are calculated values and others based on scientific trials. Care should be taken to ensure the correct set of tables is used as a slight bias in one or other direction might erase any benefits from this exercise.

Lactose

Lactose is important in piglet feeds, but it is not just lactose that piglets require to thrive on; they can use other simple sugars with equal efficiency, but then the term “lactose equivalents” must be used. Ingredients containing simple sugars can now contribute to the need for “lactose equivalents,” often at reduced cost. Such ingredients include sucrose (table sugar), fructose, high fructose corn syrup, dextrose, molasses and maltodextrins.

Phosphorus

This is the third most expensive nutrient. Total phosphorus, as a way of describing the phosphorus concentration in feed, is very inaccurate and leads to overformulation. For example, in cereals, pigs are able to utilize only one-third of total phosphorus, yet in animal protein sources, up to two-thirds of total phosphorus is being used. The intermediate term “available phosphorus,” where an ingredient’s phosphorus use was indexed against a standard source (sodium phosphate), is an acceptable form. Nevertheless, it has been surpassed by the most accurate term “digestible phosphorus.” This provides a much clearer picture of the amount of phosphorus available to the animal for productive purposes.

Vitamins and trace minerals

This is a sensitive area, where changes either way can provide significant savings in feed cost and/or animal performance. Here, it is not so much the form of describing the presence of each nutrient, but rather its actual concentration. Nevertheless, nutrient availability can be utilized in lowering overall feed specifications. The availability of vitamins is quite different among certain sources and this too should be taken into account when these premixes are designed. One clear example is sufficient to illustrate the issue. One form of copper oxide is totally unavailable to pigs, whereas a similar copper oxide is highly available.

Fiber

Fiber is undesirable in most formulas because it reduces energy density and nutrient digestibility. However, functional fibers are beneficial in improving animal gastrointestinal health. Up to this time, there has not been an agreement on which is the best term to describe the fiber fraction in feed. Therefore, the term “crude fiber” continues to be the base on which pig ingredients are evaluated. Other forms, more complex, exist, but values for many pig ingredients are yet to be determined.

Most importantly, fiber dietary specifications (minimum and maximum values) for pig formulas, other than those of “crude fiber” are very difficult to encounter in publicly available literature. All these imply that the term “crude fiber” is the best option for the present time, when all things practical are considered. Nevertheless, the nutrition community is gradually being accustomed in using terms such as insoluble and fermentable fibers, albeit we are still a long way before establishing requirements, yet alone practical recommendations.

Nutrient specifications

Table values such as those provided by scientific or commercial entities are quite common in setting target values for the above nutrients. While these examples provide an excellent starting base, modifications are required to ensure specifications meet actual animal needs.

Because of the generic form of such table values, not all cases can be covered. It is actual productive performance that should be used as a guideline in setting final formula dietary specifications. This ensures minimal feed cost and maximal animal performance. This goal can be achieved through trial and error (or via nutrient challenge trials), or by employing the use of a growth model (in the case of growing pigs). Lamentably, such table values are considered as the final word on the subject whereas, in reality, they are nothing but the starting point.

Small changes can equal large savings

Proper feed formulation concepts are often bypassed when feed savings are required. A cheaper feed does not have to be a feed of lower quality. To this end, using the correct tools (parameters and values) in formulating pig feeds, both animal performance and feed cost can be controlled toward the desired outcome.

Producers should be encouraged to ask their nutritional professionals about the latest and most advanced technology when it comes to feed formulation. Because feed accounts for at least 60% of total production cost, small changes in this area make for large savings.

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