Standard cattle unit
A standard cattle unit (SCU) is an animal of 600 kg live weight at the time of exit (turn-off) from the feedlot.
This term enables the stocking capacity of feedlots to be expressed in line with the weight of cattle turned off from the facility rather than the number of head. This concept is based on the understanding that manure production increases with cattle's live weight.
Conversion factors have been calculated based on the metabolic live weight of the cattle (i.e. live weight0.75) (see Table 1).
- Number of SCUs = number of head x conversion factor (F)
- Number of head = number of SCUs / F
|Approximate weight of beast
at turn-off (kg live weight)
|Number of standard cattle units|
The stocking density is the average feedlot pen area allocated to each beast.
It can affect the performance, health and welfare of the cattle, and the environment (such as the moisture content of the pad and, therefore, its odour and dust levels).
The total pen area does not include hospital pens and handling facilities.
- Stocking densities heavier than 10 m²/SCU are not recommended.
- A minimum stocking density of 9 m²/SCU is stipulated in the 'National guidelines for beef cattle feedlots in Australia' (CSIRO). This applies to cattle accommodated in open pens rather than shedded animals.
- Most commercial feedlots in Queensland operate at 12-20 m²/SCU.
- Stocking densities should factor in the local climate and size of the cattle in the feedlot.
- There needs to be a compromise between the potential for odour at heavier stocking densities and the incidence of dust problems at lighter densities.
Class of feedlot
The class of feedlot refers to a system of four feedlot classes that define an appropriate standard of feedlot siting, design, construction and management to restrict odour to acceptable levels for nearby receptors (towns and residences).
These standards are stringent from Class 4 to Class 1.
The effect of a feedlot's odour on receptors is limited through the selection of an appropriate class, which depends on the feedlot's size and its proximity to the receptors.
Sites that are well removed from potential receptors have less rigorous standards, resulting in less capital and fewer ongoing costs.
The class system does not account for variations in other environmental impacts, such as the potential contamination of surface or groundwater resources.
- 'Reference manual for the establishment and operation of beef cattle feedlots in Queensland', Appendix B. This includes information on the design, construction and operational specifications that apply to each class of feedlot. This publication can be purchased from the Government Bookshop.