Page 11 - National Poultry Newspaper

Shape-changing bacteria evade fowl cholera vaccines
Litter manual for Aussie chook farms
IN April 2021, a man- ual was compiled for AgriFutures Chicken Meat by Mark Dunlop from the Queensland Department of Agri- culture and Fisheries and Eugene McGa- han and Nic Gould of Integrity Ag and En- vironment, previously FSA Consulting, into litter management for meat chicken farms in Australia.
ety of reports, scientif- ic papers and guides, without there being one document that synthesises this infor- mation and makes it applicable and relevant to the various industry participants.
Litter is possibly one of the largest opera- tional investments on meat chicken farms.
The manual covers litter selection, man- agement of litter in sheds including reuse, and options and use of spent litter following removal from sheds.
Litter manage- ment can affect meat chicken health, human health, odour and dust.
It has been structured so that users can ac- cess concise informa- tion and guidance on the best management practice for each pro- cess involving litter.
Despite the litter is- sue being important for all industry par- ticipants, there hasn’t been a single point where information has been brought together and maintained in an up-to-date format.
The manual can be downloaded from agrifutures.com.au/ product/final-report- best-practice-litter- management-manual- for-australian-meat- chicken-farms/
While the indus- try has done a large amount of work in this area, the results are documented in a vari-
The best practice lit- ter management manu- al for Australian meat chicken farms collects this knowledge in one place.
The manual has been structured for users to access concise information and guidance on the best management practice for each process involving litter.
THE access to open air and an outdoor lifestyle, which is a feature of free range chicken farm- ing, may well be putting birds at a higher risk of an untimely death.
The responsible bacte- ria pasteurella multocida can also be carried and transferred to chickens from foxes, rodents and migrating birds.
proving effective against fowl cholera.
face structure, including by switching genes on and off.
The findings from this three-year national project will allow Dr Omaleki and the re- search team at QAAFI to investigate ways to over- come this adaptive abil- ity of pasteurella multo- cida – a mechanism that the bacterium uses to undermine the effective- ness of vaccines.
Researchers have long understood that despite their more socially ac- ceptable existence, free range chickens are ex- posed to more disease agents when compared to caged chickens.
Live bacteria are taken from the carcasses of an infected flock, grown in the laboratory and then killed, providing the ba- sis for a vaccine to pro- tect subsequent flocks on the same property.
Future analysis must use whole-genome se- quencing to understand how pasteurella multo- cida responds to vaccine pressure.
A related pathogen, which causes middle ear infections in humans, has also been identified as having the ability to switch genes on and off, resulting in a change in bacterial outer structure.
Recently, new research established that pasteur- ella multocida – the bac- terium that causes fowl cholera – is intuitive enough to switch on and off certain genes to out- smart vaccines, leaving free range chicken flocks exposed to the often dev- astating effects of the disease.
Dr Lida Omaleki’s re- search at UQ is part of a Queensland Alliance for Agriculture and Food In- novation project co-fund- ed by Australian Eggs and AgriFutures chicken meat program.
Dr Omaleki said the killed bacteria used in the vaccines for each farm should have the ex- act outer structure as the strain that produced the disease on that farm.
“If we can understand the specific strains in certain flocks, we will be able to better guide vaccination programs as well as identifying where the strains are coming from, and perhaps intro- duce improved biosecu- rity practices to protect the chicken flocks,” Dr Omaleki said.
Dr Omaleki’s research findings have demon- strated the potential of a similar mechanism in pasteurella multocida for the first time.
The finding from Dr Lida Omaleki, a research officer based at the Uni- versity of Queensland, also points to the need for whole-genome se- quencing to help chicken producers identify chang- es in bacterial strains and better protect their flocks.
Usinggenomicanalysis, she has discovered why some vaccines were not
However, genomic analysis has illustrated the ability of the bacte- rium to evade vaccine induced immunity by changing the outer sur-
Production levels in flocks for both meat and eggs are impacted after an infection of fowl chol- era, which is less prev- alent in chicken flocks held inside sheds because of the closely controlled environments and closer monitoring of animal health.
The most widely used form of vaccine to com- bat fowl cholera is a ‘killed vaccine’.
The research shows that traditional bacterial analysis techniques are not specific enough to identify genetic varia- tions in bacteria strains.
The death of chickens is often the first sign that a flock is infected.
Chronic symptoms can include fever, loss of ap- petite, respiratory diffi- culties and a bluish dis- colouration of a bird’s skin, wattle and comb.
Stresses such as fox or dingo attacks can also low- er immunity levels, expos- ing the chicken to greater chance of infection.
Dr Lida Omaleki is a research officer at Queensland Alliance for Agriculture and Food Innovation’s Centre for Animal Science at the University of Queensland.
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National Poultry Newspaper, August 2021 – Page 11