Guidelines for Establishment and Operation of Cattle Feedlots in ...

up, may result in increased humidity and elevated ammonia levels beneath the shade and in the
pen.
Repair and maintenance of the pen surface will also be high in this area. The area should be
regularly cleaned of wet manure to limit odour production and ammonia emissions.
Shade structures of the dimensions outlined above allow access by sunlight to the pen floor as
the shade moves across the pen throughout the day. This will assist in reducing the occurrence
of shade related wet pen conditions.
14.4.5 Structural Design of Shade Structures
Shade structures need to be designed carefully with attention paid to the loads that the structure
must bear.
Wind blowing against the structure results in directional loads. Side loading is caused by wind
action against walls and posts, while wind action on a sloping roof can cause the roof to act
either as a wing or an aerofoil depending on wind direction.
These forces must be taken into account when designing the structure.
The mass of material supported by the structure is called the “dead load”. The dead load of
galvanised sheeting is higher than for shade cloth, so the support structures need to be more
substantial.
The dynamic load of the shade structure is a load that varies in character. It typically results
from movement of a structural member or other variable or oscillating force. For example wind
gusts cause dynamic loading by swinging of the structure or alternating uplift and downdraft
loads.
The ability of the structure to shed load and damp out oscillations becomes important when
taking account of dynamic loads.
It is recommended that engineering advice be sought in the design and placement of feedlot
shade structures.
14.5 Mandatory Reporting Of Cattle Deaths
Mandatory reporting is required by all feedlots on animal welfare and exotic disease alert grounds.
Where an unusual number of deaths and/or sick cattle occur in a 24 hour period a veterinarian
must be consulted to establish the cause of the incident. An unusual number of deaths and/or sick
cattle are defined according to the number of cattle that the feedlot is feeding at the time of the
incident. The draft requirements are as follows:-
Feedlots with up to and including 5000 head – greater than 3 deaths or 20 pulls in a 24
hour period
Feedlots with more than 5000 head on feed – loses greater than 0.04% of the cattle on
feed, or pulls greater than 0.4% of the number of cattle on feed in a 24 hour period.
Where the deaths/illnesses are suspected to be caused by an emergency/infectious disease
AUSVETPLAN procedures must be implemented.
Where an emergency/infectious disease is confirmed not to have caused the deaths/illnesses
reporting procedures according to the level shown in table 12 must be implemented.
Guidelines for Establishment and Operation of Cattle Feedlots in South Australia, 2 nd Edition 62