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6.12 Sheltered feed troughs
Standard 3.7 c iii stipulates that sheep prepared in paddocks between May-October must be fed from fully sheltered feed troughs.
This standard is based on principles aimed at ensuring feeding systems allow feed to remain dry and with minimal faecal contamination throughout the feeding period More, 2002a. It also assists in
maintaining feed intake by ensuring animals can access feed that is not affected by rain or environmental contaminants.
An inadvertent complication resulting from this requirement was observed by the author during the LIVE.123 project when project team members were present at registered premises in South
Australia and Victoria in the winter. The registered premises tended to have open feed troughs in many paddocks and sheltered feed troughs just in some paddocks, presumably to conserve costs.
In the non-restricted period November-April this allowed a registered premise to house sheep in any available paddock. At any given time premises had the potential to employ strategies including
lower stocking densities in paddocks and paddock rotation that might conceivably also act to lower stress and minimise risks of disease.
In the winter months premises were restricted to housing sheep in paddocks that had sheltered feed troughs. In some cases, this restriction may have inadvertently resulted in increased salmonella
exposure risk rather than reduced salmonella exposure risk. This was considered possible mainly when the same paddocks were used for subsequent consignment preparation and when conditions
wet weather, susceptible sheep, presence of salmonella favoured the shedding of increased numbers of salmonella organisms.
These conditions may have favoured the build-up of heavy environmental contamination of salmonella organisms over time and inadvertently favoured the creation of conditions that could lead
to increased risk of salmonellosis. These factors could have contributed to increased salmonellosis risk even though the feed troughs themselves were in compliance with requirements and feed was
being kept dry and uncontaminated.
This issue is an example of a specific regulatory requirement that was put in place for the best of intentions and that is justified based on science, but where there are unintended consequences that
may result in some years from the way that the requirement has been implemented in some premises.
It is not necessarily appropriate to require all premises to have sheltered feed troughs in all paddocks. Nor is it appropriate to require lower stocking densities or forced paddock rotations.
The value of this example is to reinforce the notion that the causal web for salmonellosis is complex and multi-factorial and dynamic. Running sheep at maximal stocking densities allowable under
ASEL and using the same paddocks for subsequent consignments may be fine except under some
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conditions. If there was an adverse climatic event or a minor salmonellosis event some sick sheep in one line, then these conditions could result in contamination of one or more paddocks and lead to
elevated risk. If this situation could be recognised through monitoring then it could potentially allow separate management of an affected line and possibly spelling of that paddock for a future
consignment to allow environmental pathogen loads to decline. These issues have been discussed and options outlined for studies to better understand the potential of practices such as salmonella
vaccination and also environmental and animal management to minimise salmonella risk Perkins et al., 2009.
6.13 Wool length
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