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The animal mortality rate calculator helps producers use their farm records to measure the level of mortality or death in their farm animals. You can use this calculator to determine your poultry mortality rate, cattle mortality rate, or the different mortality measures within a time interval for any herd or flock. Simply input the opening stock you started a growing cycle with and the number you currently have or have left at the end of the growing cycle.

If you are wondering, "What does mortality rate mean?" or if you're curious about the death rate of farm animals, how to calculate mortality rate, or how to calculate animal death rate?, then keep reading.

This article provides you with useful information on the mortality rate of farm animals, the causes and impact on animal health, and how you can modify your farm production strategy to improve animal health, reduce the animal death rate and increase your farm's productivity. We also created many tools to help you estimate the length of your farm animal's pregnancies. Check out one of these: swine gestation calculator, cow gestation calculator.

What is the mortality rate or animal death rate? - Animal mortality definition

Animal mortality basically refers to death in an animal population. Whether it's a paddock, pen, pond, poultry mortality rate, or cattle mortality rate, it is almost impossible to avoid some mortality as the animal population increases. Hence, the goal is to keep mortality at a minimum, such that it does not impact your animal production goals in terms of herd growth, sales, or consumption.

Some key parameters to consider when evaluating the productivity of an animal production enterprise are:

  • Reproductive rate – Measures the fertility of the animals, including the female animals' parturition (number of childbirths per female per year) and proliferation (number of offspring per parturition) rates;

  • Feed conversion ratio – Measures how efficient the animals turn the feed they consume into the desired products (biomass, eggs, or milk);

  • Milk offtake – For dairy production enterprises, measures the amount of milk used for human consumption (excluding that used to feed the young lambs, calves, or kids);

  • Offtake rate – A measure of the proportion of animals sold or consumed for meat in a year; and

  • Mortality rate.

πŸ”Ž Learn about a true cost of eating meat in the meat footprint calculator.

The mortality rate, expressed as a percentage, measures the number of deaths in your animal population over a particular growing cycle or time period. It is an important indicator of the quality of care provided to raised animals and the severity of external factors, such as disease outbreaks or droughts. Therefore, the animal mortality rate calculator helps estimates the risk of an animal dying on a farm.

According to its goal, the production parameters are critical when accessing farms because they directly influence the management decisions. A farmer interested in herd growth will focus on improving the herd's reproductive rate, while a farmer concerned about sales at the end of the season will want to improve the farm's offtake rate.

However, the mortality rate directly impacts population dynamics and a farm enterprise's gross profitability long-term. Thus, if you can manage the mortality rate well by ensuring that your animals stay healthy and well-fed, you will better increase your farm's productivity in the long-term than if you were to focus solely on the reproductive rate, for instance. But managing mortality is one of the greatest challenges in animal husbandry, especially as the animal population increases.

How to calculate mortality rate, cumulative mortality, and case mortality?

The simple formula to calculate animal mortality over a time period is:

Mortality = Number of deaths = Opening stock + Number of newborns - Number of animals sold - Closing stock


  • Opening stock - The number of animals at the beginning of the growing season;

  • Closing stock - The number of animals at the end of the growing season.

The mortality rate is determined as a ratio of the number of deaths relative to the opening stock and number of newborns:

Mortality rate % = Mortality / (Opening stock + Number of newborns) * 100%

The lower the mortality rate, the fewer dead farm animals.

Aside from the mortality rate, other mortality measures offer an in-depth understanding of animal production, but these are mostly advanced measures for large enterprises. Two of the most simplistic measures are:

  • Cumulative mortality which measures the risk of animals dying from disease during a specified period:

Cumulative mortality = Number of deaths / Closing stock


  • Case mortality, or case fatality rate, which measures the proportion of infected animals (cases) diagnosed with a specific disease that died from it over a specified period of time:

Case mortality = Number of deaths from a disease / Number of disease cases * 100%

Case fatality as a mortality measure provides information on:

  • The severity of disease;
  • Comparing the cause and outcomes of a disease in different environments, treatments, animals; and
  • Evaluating the effectiveness of new treatments.

Example - Calculating and translating the result of mortality measures

Let's consider two pig farms, FarmOne and FarmTwo. Both farms have a population of 200 pigs each. Assuming a disease outbreak, FarmOne recorded 53 pigs infected, with 18 dead from it. In FarmTwo, 19 pigs were infected and 9 died from it.

We can determine the mortality rate and evaluate mortality measures – cumulative mortality and case mortality – in both farms as follows:


Number of deaths = 18

Mortality rate = 18/200 * 100% = 9.0%

Cumulative mortality = 18/182 = 0.099

Case mortality rate = 18/53 = 0.339 = 0.339 * 100% = 33.9%


Number of deaths = 9

Mortality rate = 9/200 * 100% = 4.5%

Cumulative mortality = 9/191 = 0.047

Case mortality rate = 9/19 = 0.474 = 0.474 * 100% = 47.4%

Translating the results:

  • Mortality rate: The result reveals a higher mortality rate in FarmOne which means more animals died from the disease than in FarmTwo.

  • Cumulative mortality predicts a higher probability of the disease incidence in FarmOne. But the Case mortality rate shows that the impact of the disease is greater in FarmTwo.

A farm manager can interpret these results from the animal mortality rate calculator to mean FarmTwo has to do more in curtailing the disease even though it had a lower mortality rate. In general, keeping these numbers low is better for farm animal health.

Factors influencing animal health and animal mortality

Poor Nutrition

Providing adequate feed and quality water for animals to grow, develop, produce heat to keep warm, and fight illnesses is paramount for success. Without proper feeding and an adequate regimen, animals will not maximize the feed they consume, and they may not be strong enough to stay alive if they fall ill.

Keeping aged animals

Animals are most prone to death in their early days of life (take extra care of newborn animals!) and during childbearing (care for your breeders!). The risk of death diminishes as the animal grows but rises again as they age until it surpasses that of the first year of their life. So, it is recommended to depose your aging animals if you want to keep the mortality rate in farms or herd low. Keeping aged animals longer than necessary can result in death or animals being in such poor health that they require euthanasia.

Poor environmental condition

The environment of your animals must be clean, airy, and safe. Animals have to be comfortable if you want them to thrive and produce efficiently. Some points to remember are:

  • Don't overstock the pens and ponds;
  • Store chemicals safely;
  • Maintain proper lighting of the farm buildings; and
  • Monitor and avoid air and water pollution on the farm.

Not vaccinating your animals from preventive diseases

Animal diseases are almost certainly the primary cause of mortality on a farm. It is imperative to maintain a high level of biosecurity measures to prevent disease outbreaks. More importantly, vaccinating your animals against preventable diseases is mandatory if you don't want to risk exposing your animals to a pandemic and death.

To overcome the challenge of animal mortality, it is essential to monitor your farm's mortality rate to gain an insight into your animals' welfare. By keeping proper records of farm activities, you can calculate the mortality rate of your animals and determine the extent of a potential problem so that you can tackle the problem quickly. Admittedly, the accuracy and extent of the animal mortality rate calculator will vary with different animals and the accuracy of the data used to determine death rate. Therefore, farmers are advised to take daily stock and record mortality rates on a stock per day or farmhouse basis.

If you are raising animals like chickens or fish, which you can sell off in a relatively short time, it may be easier to determine the mortality rate for that particular growing season than when you are raising a cattle herd. Thus, a pastoral farmer needs to keep even more detailed records and needs a minimum of three years' records to analyze their enterprise's economic status adequately.

Problems of the mortality rate parameter

  • Depending on farm management's goals, the Mortality rate can cause a farmer to overestimate survival and underestimate mortality. As seen in the example with FarmTwo, if the farmer's goal is herd growth and mortality below 5%, achieving the low mortality rate without considering other measures could give a biased impression off farm animal health.

  • Measuring mortality rate is only as good as the data used in the calculations. Therefore, farmers need to have good records to get accurate results.

  • The measures required to estimate mortality must be carried out within a specific timeframe for a specific disease. If the disease duration lengthens, the animals will likely die from other causes unrelated to the disease, resulting in an overestimation of the case mortality rate. And, when the animal actually dies from the disease but is not accounted for, the result can be underestimated. Thus, the case mortality rate is mainly used to evaluate the outcome and treatment effect for severe diseases within a short survival period.

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Related calculators
Mortality rate
Opening stock
Number of newborns
Number of animals sold
Closing stock
Number of deaths
Mortality rate
Cumulative mortality
Disease mortality rate
Number of disease cases
Number of deaths from disease
Case mortality
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