These figures belong to the named source and method. Historical costs are not current quotations. A value without its stage, material basis or measurement location is not a farm instruction.
| What is measured | Value and basis | Source and limitation |
|---|---|---|
| Fly screening on doors and ventilators | 35 mesh or finer | NHB DPR model, 2018. Nylon net. |
| Fresh-air inlet filter | 2 micrometre mesh | ICAR-DMR manual, 2011. Restricts disease and competitor mould spores. |

