Free · Livestock calculators 🐄

Animal Stock Balance and Death Ratios

Reconcile births, sales and closing stock, then calculate explicitly labeled death ratios.

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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

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Formula and method

Opening stock 100 plus 20 births, less 10 sales and closing stock 100, leaves 10 deaths. Two disease deaths among 10 cases give a case-fatality fraction of 20%.

Deaths = opening + births − sold − closing; period death fraction = deaths/(opening + births); deaths-to-survivors = deaths/closing; case fatality = disease deaths/cases.

Worked example

Enter these known values and leave the other values blank.

Opening stock
100
Number of newborns
20
Number of animals sold
10
Closing stock
100
Number of disease cases
10
Number of deaths from disease
2
Available stock
120
Number of deaths
10
Deaths / opening stock plus births
8.333 %
Deaths / closing survivors
0.1
Disease deaths / disease cases
20 %

Assumptions and limitations

  • The stock balance assumes all additions are births and all non-death removals are sales. Purchases, transfers and escapes must be reconciled separately.
  • The period fraction denominator is opening stock plus births, not animal-time at risk. It is not an epidemiological incidence rate.
  • Deaths divided by closing stock is a deaths-to-survivors ratio and can exceed 100 percent. It is not cumulative mortality risk.
  • Counts are nonnegative whole numbers; disease deaths cannot exceed disease cases. A positive available stock and positive disease case denominator are required when calculating their ratios.
  • Use one reporting period and one coherent animal population. A zero closing stock hides the deaths-to-survivors result.

Common questions

Is deaths divided by closing stock a mortality risk?

No. It is a survivors-based ratio and can exceed one.

Where should purchases be entered?

This form has no purchase field. Reconcile those additions in your opening-stock accounting before using it.

References

Declare the physical or stated approximation domain; captured arithmetic is unchanged.

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