The Parametrics option is a means of determining the effect of changes in the nutrient content, or of changes in the content or cost of an ingredient, on the cost of the feed being formulated. A range of nutrient or ingredient contents is specified and the cost of each of the resultant feeds is displayed in graphic form.
This option can be useful for:
- Determining the effect of a change in ingredient cost on its inclusion rate in the formulation.
- Seeing which ingredients are included or excluded as the cost of an ingredient changes.
- Discovering the range within which the value of a nutrient or an ingredient must lie in order for the formulation to reach a feasible solution. Feasible ranges may also be used for this purpose (see screenshot below).
- Quickly doing a very large number of formulations.
Selecting values to paramaterise
Generally only one nutrient or ingredient will be parameterised at a time, but it is possible to increase the number (see below).
The default Number of intervals is 20, and the Interval size is calculated correspondingly. The number of formulations for one selected ingredient/nutrient is always one more than the number of intervals because WinFeed does a formulation for both the start and the end value of the range.
For multiple parameterisations
The list box on the left contains a list of all the ingredients/nutrients whose values are to be incremented over the given range.
WinFeed will do a formulation for each possible permutation of values that is possible from the ranges defined for the individual ingredients/nutrients. Therefore, the total number of formulations is the product of the number of intervals, plus 1, for each of the ingredients / nutrients. Consequently, by selecting more than one ingredient/nutrient for paramaterisation the number of required formulations quickly multiplies to a large number. It is therefore advisable to change the number of intervals thereby restricting the number of formulations to a realistic number.
Changing the range
Interpreting results from ingredient objective value parametrics
Parametrics on Cost
The example below illustrates the change in soybean oilcake inclusion rate in a given feed when the ingredient price is increased from 4275 to 7125.