An enzyme supplier is introducing a new phytase, and its technical sheet carries a long matrix table: values at a given dose for available phosphorus, calcium, sodium, metabolisable energy and several digestible amino acids. The purchasing manager asks how much the cost per tonne would drop if all of these values went into the formula. The nutritionist asks a different question: how much of this will actually show up in our feeds?
What is a matrix value?
Enzymes do not give the animal nutrients directly. They let it digest more of the nutrients already in the feed. Phytase releases part of the phosphorus bound in phytate in plant ingredients. NSP enzymes such as xylanase reduce the viscosity caused by soluble fibre in wheat and barley, and improve the digestion of energy and amino acids.
In formulation, this effect is reflected by defining the enzyme like an ingredient with nutrient values. A kilogram of phytase is treated as if it adds a set amount of available phosphorus and calcium to the formula. With that contribution counted, the formula uses less dicalcium phosphate and limestone. The matrix value is the size of that virtual contribution.
The phytase saving
Take an example, with illustrative numbers. Our broiler grower diet without phytase contains 1.4 percent dicalcium phosphate. When we add phytase and use the supplier's recommended dose with matrix values of 0.12 points for available phosphorus and 0.11 points for calcium, dicalcium phosphate falls by about 0.65 points. With dicalcium phosphate at 30,000 TRY a tonne, that saves about 195 TRY per tonne of feed. If we use 100 grams of phytase per tonne at 400 TRY a kilogram, the enzyme costs 40 TRY a tonne. Taking the small change in limestone into account, the net saving is around 150 TRY a tonne.
That saving comes from phosphorus and calcium alone. If the supplier's energy and amino acid values are added as well, the formula also uses less corn and soybean meal and the saving grows considerably. This is where the real question starts.
How much should you use?
Phosphorus and calcium matrix values are generally reliable, because that is the primary effect of phytase and it is backed by many trials. Energy and amino acid values vary more from feed to feed, with the age of the animal and with the make-up of the diet. Many nutritionists prefer to use phosphorus and calcium at full value and energy and amino acids at half or two-thirds of the recommendation. This cautious approach gives up part of the saving, but it does not put flock performance at risk.
Another important issue is counting the same effect twice. If a formula contains both phytase and xylanase and a full energy matrix is used for each, the combined effect can look larger than it really is. The two enzymes partly release the same nutrients. Used together, their combined effect is usually smaller than the sum of their separate effects.
Dose and substrate
A matrix value is not a fixed number. The phosphorus phytase can release depends on how much phytate is in the feed. A formula built on meat and bone meal or other animal sources, with few plant ingredients, has little phytate, and phytase cannot deliver the value on the technical sheet there. In the same way, the energy contribution of xylanase rises with the share of wheat and barley in the feed. In a corn-based feed, the same xylanase has a much smaller effect.
Dose does not work proportionally either. Doubling the phytase dose does not double the phosphorus released. At high doses, each extra unit of enzyme adds less and less. That is something to watch for companies working with high phytase doses. Applying matrix values defined for one dose proportionally to other doses makes the saving look bigger than it is.
When prices change, so does the enzyme's value
The phytase saving we worked out above is closely tied to the price of dicalcium phosphate. When phosphate prices fall, the value of the phosphorus phytase releases falls with them. When phosphate prices rise, the same dose becomes much more valuable. So rather than deciding on enzymes once and forgetting about it, the decision should be reviewed when prices change noticeably.
An easy way to see this is to look at the shadow price of available phosphorus in the solve without enzymes. The shadow price shows the effect on formula cost of raising available phosphorus in the feed by one unit. If in our example that value is about 2,200 TRY a tonne per one percent, the 0.12 points phytase supplies are worth roughly 260 TRY a tonne. Taken together with the calcium effect and the cost of the enzyme, this figure quickly shows which dose makes sense in which price setting.
Setting it up properly in formulation
So defining the enzyme matrix as an ingredient with fixed values is only a start. A more realistic approach ties the enzyme's contribution to the dose and to the amount of substrate in the feed. The enzyme matrix in OptiFormula, which depends on dose and substrate, lets you build that relationship. When the wheat share in the formula changes, the energy contribution of xylanase changes with it, and when phytate content changes, so does the phosphorus contribution of phytase.
Then there is verification. In formulas that use enzymes, it is important to analyse feed regularly, for instance by having the phytase activity actually present in the feed measured. In plants with high pelleting temperatures, the activity of some enzymes can fall during production. The matrix value on paper only means something if the enzyme is really active in the feed.
Deciding with your own data
Enzyme matrices are among the most effective tools for lowering feed cost. But every matrix value summarises trials run under particular conditions. Judging those values against your own ingredients, your own doses and your own animal performance data keeps the saving from staying on paper. Starting cautiously and raising the values step by step alongside flock results is the successful path we see most often in the field.
