This vCalc agriculture equation, created originally by vCalc author MWelly, computes the population of a free range poultry farm based on the total area of the farm and the standard number of birds allocated to any area of the farm, known as the Stocking Density.
The European Union has defined a maximum number of chickens per hectare as a standard definition to follow to be officially considered a valid free-range poultry farm.1 This standard Stocking Density is defined as follows:
"the open-air runs must at least satisfy the conditions specified in Article 4(1)(3)(b)(ii) of Directive 1999/74/EC whereby the maximum stocking density is not greater than 2500 hens per hectare of ground available to the hens or one hen per 4m2 at all times and the runs are not extending beyond a radius of 150 m from the nearest pophole of the building; an extension of up to 350 m from the nearest pophole of the building is permissible provided that a sufficient number of shelters and drinking troughs within the meaning of that provision are evenly distributed throughout the whole open-air run with at least four shelters per hectare."
Since vCalc's vArea equation tells us there are 2.47105381467165 acres in a hectare, the acre-equivalent of the European Union's stocking density standard is:
`"stocking density" = "2500 hens" / "hectare" * "1 hectare" / "2.47105381467165 acres" approx "1011.71 hens" / "acre"`
If you want your free range chickens to be even healthier, you can decrease the input Stocking Density, which then assumes more running room on average for every chicken.
If you have a poultry farm allowing free range running area of 1200 acres, the maximum number of chickens you can have and still be considered a compliant "free range" poultry farm by the European Union is: 1214056 chickens (less than 1214056.92 computed free range chickens)