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Rural Industries
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RIRDC Completed Projects in 2000-2001 & Research in Progress as at June 2001
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* Indicates a joint chicken meat and egg program project. These projects will appear in both sections of this report.
Flock Health
Bird Nutrition and Feed Supply
Food Safety
Animal Welfare
| DAV-162A | A welfare audit for the transport and processor sectors of the broiler industry |
Environmental Management
| DAW-94A | Conditioning and Analysis of Broiler litter to prevent fly breeding |
Other
| DAN-142A | Production of Trial Distance Learning Materials for the Poultry Industry - Stage III |
| Project Title | Revision of the AUSVETPLAN Disease Strategy document on very virulent Infectious Bursal Disease |
| RIRDC Project No: | BTT-2A |
| Researcher: | Dr Clive Jackson |
| Organisation: | Biological
Technology Transfer
2 Victory Avenue CAMDEN NSW 2570 |
| Phone: | (02) 4655 4007 |
| Fax: | (02) 4655 4008 |
| Email: | cawjacko@ozemail.com.au |
O bjective |
· To revise the AUSVETPLAN Disease Strategy document on very virulent infectious bursal disease. |
Background |
In 1998, Dr Jackson developed an AUSVETPLAN Disease Strategy Document as part of a consultancy to the DPIE. That Strategy Document was developed because of the serious economic impact that very virulent Infectious Bursal Disease (vvIBD) would have on the poultry industry should it gain entry into Australia. The potential annual loss was estimated to be in the order of $50 million. A revised Strategy Document was developed using the Newcastle Disease (ND) Strategy Document as a model. However, experiences gained through the implementation of that document in the course of the 1998-2000 outbreak of virulent ND in NSW resulted in the need for further revision of the Disease Strategy document for vvIBD. |
Research |
The
revision was undertaken with the assistance of a corresponding committee
of Australian scientific experts on IBD. The Strategy Document was
rewritten to incorporate decisions from a government/industry meeting held
on 19 August 1999. The revised Strategy Document also considered
the role played by government and industry during the 1998-2000 eradication
of virulent Newcastle disease in NSW. It also considered the new
cost-sharing agreement for exotic disease control and eradication.
|
Outcomes |
A
revised Disease Strategy document has been developed for review by RIRDC
Egg and Chicken Meat Programs and industry. The revised Strategy
Document should provide the industry and government with a contemporary
document on which to base an eradication program. The Strategy Document
takes into account the current funding arrangements for exotic disease
control in Australia. It attempts to define the resources required
by industry and government. It also provides industry with guidance
in undertaking a risk analysis of the benefits to be derived from pursuing
eradication with limited resources and funding.
|
Implications |
The
existence of a Disease Strategy document focuses the attention of the industry
on the need to remain vigilant against the entry of vvIBDV. It emphasises
the need to continue to develop rapid diagnostic tests to detect the presence
of any very virulent viruses as early as possible. It also demands
the availability of funds and resources to undertake any eradication program.
|
Publications |
Jackson,
C.A.W. (2001) AUSVETPLAN Disease Strategy for very virulent infectious
bursal disease virus (vvIBDV) eradication. Proc. AVPA Scientific Meeting
6-7.2.01 University of Sydney, p15.
Jackson, C.A.W. (2001) A Disease Strategy for the prevention and eradication of very virulent infectious bursal disease virus (vvIBDV). Proc. XIIth International Congress of the WVPA, Cairo, 17-21.9.01 (Abstract) (Submitted for publication). |
| Project Title | Postgraduate Scholarship – Matthew Rudd: Identification of virulence determinants of infectious bursal disease virus (IBDV) |
| RIRDC Project No: | CSA-4J |
| Researcher: | Mr Matthew Rudd and Dr Jagoda Ignjatovic |
| Organisation: | CSIRO
Livestock Industries
Australian Animal Health Laboratory (AAHL) Private Bag 24 GEELONG VIC 3213 |
| Phone: | (03) 5227 5769 |
| Fax: | (03) 5227 5555 |
| Email: | Jagoda.Ignjatovic@csiro.au |
Objectives |
·
To characterise and sequence a very virulent (vv) exotic strain of infectious
bursal disease virus (IBDV) and identify genomic region(s) which may influence
pathogenesis.
· To compare and contrast the pathogenicity of attenuated and very virulent IBDV (vvIBDV) strains in vivo, and identify criteria which might differentiate between the two strains. · To establish a reverse genetics system for the recovery of infectious IBDV from cell culture, embryonating eggs and/or directly from SPF chickens. ·
To swap genomic material between attenuated and vvIBDV strains and assess
the impact of such manipulations on pathogenicity in vivo.
|
Background |
Since first reported in 1989, vvIBDV has spread rapidly throughout Europe, Asia, and many other countries. Australia is currently free of such strains. This project seeks to identify potential virulence markers of IBDV for the development of rapid and highly accurate diagnostic tests which could be used to detect any incursion of exotic vvIBDV strains, should this ever occur. |
Research |
An
Indonesian vvIBDV strain was completely sequenced and the deduced amino
acid sequences were aligned with the corresponding sequences of published
IBDV strains to identify amino acids which are conserved solely in very
virulent strains.
An endemic attenuated IBDV strain (002-73) and an Indonesian vvIBDV strain (Tasik94) were both extensively characterised in vivo, and the ability of several biological assays to differentiate between the two strains were assessed. Genomic material, corresponding
to a portion of the VP2 protein, was swapped between the attenuated 002-73
and very virulent Indonesian Tasik94 strains to generate recombinant IBDV.
A reverse genetics system will be used to recover infectious recombinant
virus. Pathogenicity testing of the recombinant virus will be used to assess
the significance of putative virulence determinants identified and to provide
valuable information which will assist in the development of a diagnostic
assay.
|
Implications |
Further work needs to be conducted to recover and assess recombinant virus(es). The successful identification of virulence determinants is a prerequisite for developing diagnostic tests needed to monitor the field situation of IBDV in Australia. |
Publications |
Rudd,
M.F., Heine, H.G., Parede, L., Sapats, S.I., Ignjatovic, J. (2001)
Characterisation of an Indonesian strain of very virulent infectious bursal
disease virus (vvIBDV). Proc. Int. Symp. Infectious Bursal Disease Virus
and Chicken Anemia. In press.
Currently in preparation:
Rudd, M.F., Heine, H.G., Sapats, S.I., Ignjatovic, J. Identification of putative virulence determinants of infectious bursal disease virus (IBDV). Manuscript in preparation for submission to Virus Research. |
| Project Title | Therapeutic applications of chicken interferon gamma in poultry |
| RIRDC Project No: | CSA-7J |
| Researcher: | Dr John Lowenthal |
| Organisation: | CSIRO
Livestock Industries
Australian Animal Health Laboratory (AAHL) Private Bag 24 GEELONG VIC 3213 |
| Phone: | (03) 5227 5759 |
| Fax: | (03) 5227 5531 |
| Email: | john.lowenthal@li.csiro.au |
Objective |
· To enhance disease resistance and vaccine efficacy in poultry by administering therapeutic doses of chicken interferon-gamma to commercial broilers and layers. |
Background |
Safe, natural alternatives to antibiotics for the maintenance of optimal growth rates and flock health in chickens are being sought by the poultry industry worldwide. Cytokines are natural proteins that are produced by the body’s immune system during infection. Their ability to protect against disease make them excellent candidates as naturally occurring therapeutics. |
Research |
Previous studies on chicken interferon gamma (ChIFN-g) identified it as having therapeutic potential. In this project, the ability of ChIFN-g to act as a growth promoter and vaccine adjuvant was assessed in trials using broiler chickens under commercial conditions. |
Outcomes |
An Escherichia coli expression system was developed for the large scale production of recombinant ChIFN-g protein. The recombinant ChIFN-g was found to be biologically active. Monoclonal antibodies were produced and an ELISA was developed for the detection of ChIFN-g. Treatment of broilers with ChIFN-g resulted in enhanced weight gain over a period of up to eight weeks compared to control birds. ChIFN-g treatment also reduced weight loss suffered by birds following infection with Eimeria acervulina. |
Implications |
Rapid transfer of this technology to the Australian poultry industry is anticipated. These results show the feasibility of using cytokines as natural therapeutics and adjuvants. Additional cytokines have recently been identified, including interleukins -2, -6, -15 and -18. These are now available for a similar type of assessment. The particular activities of these new cytokines make them attractive new treatments for diseases such as coccidiosis, Marek’s disease and infectious bronchitis. |
Publications |
Lowenthal, J.W., O'Neil, T.E., Strom, A.D.G., and Andrew, M.E. (1999) Cytokine therapy: a natural alternative for disease control. Vet. Immunol. Immunopathol. 72, 183-188. |
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Lowenthal,
J.W., Lambrecht, B, van den Berg, T.P., Andrew, M.E., Strom, A.D.G., and
Bean, A.G.D. (2000) Avian cytokines – the natural approach to therapeutics.
Dev.
Comp. Immunol. 24, 355-365.
Lowenthal, J.W. (2001) Therapeutic applications of cytokines - what can the chicken teach us? Avian Dis. (in press). Lowenthal, J.W., Richards, G.G., Bean A.D.G., O’Neil T.E., Hilton L.S., Tyac S., Pooley, C., and Johnson M.A. (2001) New vaccination strategies for control of coccidiosis. Avian Dis. (in press). Hilton, L.S., Bean, A,G.D., and Lowenthal, J.W. (2001) Recent advances in avian cytokines. Vet. Immunol. Immunopatol. (Invited Review – in press). Lowenthal, J.W. et al. Chicken interferons: natural therapeutics in poultry. Avian Immunology Research Group Meeting, Turku, Finland 1998. Lowenthal, J.W. Cytokine therapy – a natural alternative for disease control. 4th Asia Pacific Health Conference, Melbourne, 1998. Lowenthal, J.W. Cytokine therapy – a natural alternative for disease control. 5th International Veterinary Immunology Symposium, India, 1998. Lowenthal, J.W. Practical applications of chicken cytokines. 11th Australian Poultry and Feed Convention, Gold Coast. 1999. Lowenthal, J.W. et al. New strategies for enhancing immunity to Eimeria: interferon gamma is the natural approach to disease control. Vaccines against Coccidioses conference, Dublin, 2000. Lowenthal, J.W. Therapeutic applications of cytokines - what can the chicken teach us? Avian Immunology Research Meeting, Cornell University, USA, 2000. Lowenthal, J.W. et al. New vaccination strategies for control of coccidiosis. Avian Immunology Research Meeting, Cornell University, USA, 2000. Lowenthal, J.W. et al., Cytokines are the next generation of therapeutics. AVAP Meeting, Attwood, Vic. Oct 2000. |
| Project Title | NDV vaccination strategies aiming to induce high HI titres in elite breeding and layer flocks |
| RIRDC Project No: | DAN-159J |
| Researcher: | Dr George Arzey |
| Organisation: | NSW
Department of Agriculture
Elizabeth Macarthur Agricultural Institute (EMAI) PMB 8 CAMDEN NSW 2570 |
| Phone: | (02) 4640 6333 |
| Fax: | (02) 4640 6300 |
| Email: | george.arzey@agric.nsw.gov.au |
Objective |
· To identify strategies capable of producing the highest and most persistent mean HI titres in vaccinated flocks. |
Background |
The recent availability of inactivated ND vaccines in Australia has broadened the scope for effective long-term protection of birds against Newcastle disease. However, no sound data was previously available on the HI titres elicited when V4 was used as the priming vaccine. The present study was undertaken in order to assess a range of vaccination strategies in caged layers with the use of V4 as the priming agent |
Research |
Ten different vaccination strategies were evaluated by monitoring the NDV HI response over a period of 28 weeks in serologically negative 18 weeks old pullets housed in commercial cages. |
Outcomes |
Any of the combinations of live V4 plus inactivated vaccine trialled should protect a flock against clinical Newcastle disease. For protection against a drop in egg production, the strategies in which V4 was followed by inactivated vaccine four weeks later can be considered protective up to 24 weeks post initial vaccination. Protection against infection for up to three months (as determined by reduced shedding of a virulent virus) can be expected with V4 delivered orally followed with inactivated vaccine four weeks later. The studies also confirmed the poor ability of V4 to spread in flocks. |
Implications |
The study demonstrated that V4 used as a priming vaccine with a selective combination of an inactivated vaccine can produce high and persistent NDV HI titres that are comparable to those elicited by other live overseas vaccines in combination with inactivated vaccines. |
| Project Title | Investigations into the management of the darkling beetle, Alphitobius diaperinus (Panzer) |
| RIRDC Project No: | DAQ-244J |
| Researchers: | Mr Trevor Lambkin and Mr MC Cameron |
| Organisation: | Department
of Primary Industries (Qld)
Farming Systems Institute 80 Meiers Rd INDOOROOPILLY QLD 4068 |
| Phone: | (07) 3896 9434 |
| Fax: | (07) 3896 9446 |
| Email: | lambkit@dpi.qld.gov.au, camerom@dpi.qld.gov.au |
Objectives |
·
To review the relevant literature pertaining to A. diaperinus research
and thereby develop an improved understanding of the ecology of the pest.
·
To develop an insecticide resistance testing method for A. diaperinus
and subsequently survey and test broiler shed and egg barn pest populations
in south east Queensland for insecticide resistance.
|
Background |
The darkling beetle, Alphitobius diaperinus (Panzer) is a common cosmopolitan insect pest of poultry houses, in particular broiler sheds and egg barns, and is capable of transmitting a large number of poultry diseases and parasites. In recent concern has been expressed about increasing beetle numbers in broiler sheds and the pest’s potential to breach farm bio-security. In spite of the occurrence of the pest on almost every Australian poultry farm, no previous Australian research has been undertaken to determine the pest’s behaviour and its insecticide resistance status. Research commenced in 1998 to address these gaps in our understanding of the pest; in particular, to develop a better understanding of the ecology of the pest and to determine if resistance to fenitrothion (Folithion®) and cyfluthrin (Tugon®) has occurred in pest populations. |
Research |
A review of scientific literature on darkling beetle research was undertaken to provide improved knowledge of the pest’s ecology, published research results and possible control strategies. Work was undertaken towards the development of an effective and efficient laboratory culture method for A. diaperinus, in order to provide a constant and adequate supply of beetles for laboratory research and testing with insecticides. A laboratory insecticide-resistance testing method was developed to provide the tools necessary to identify and characterise any insecticide resistance in A. diaperinus populations. A survey was undertaken of local broiler shed and egg barn beetle populations and these populations were subsequently tested with fenitrothion (and some with cyfluthrin). Each population tested was compared to a susceptible reference population and from this comparison a level of resistance was determined. |
Outcomes |
The scientific literature review and project field studies have indicated that the pest’s ability to avoid contact with insecticides contributes to A. diaperinus control failures. This behaviour, together with predominantly clay-floored sheds in most broiler sheds contributes to problems with control after clean-outs, as many individuals stay concealed in the floor and do not receive a lethal dose of insecticide. The development of a laboratory culture method has provided adequate numbers of some test insects. Problems with the culture method arose during the latter part of the project due to mite infestations, and these have hindered the availability of insects for testing. The development of fenitrothion and cyfluthrin resistance testing methods has been successful. Test results have shown that insects from south east Queensland broiler systems have strong fenitrothion resistance and some cyfluthrin resistance, and preliminary results indicate that populations of A. diaperinus from some production areas, for example Armidale and the Atherton Tablelands, have quite weak fenitrothion resistance. Insecticide resistance levels in insects from other intensive livestock systems, including egg barns are generally weaker, and all levels of resistance are directly related to duration and frequency of insecticide use. |
Implications |
Insecticide
resistance is not the major factor that determines beetle population sizes
in broiler sheds. There is no relationship between anecdotal estimates
of broiler beetle numbers and fenitrothion and cyfluthrin resistance levels,
ie- population sizes of insects in different broiler sheds, with similar
levels of insecticide resistance, can be very different. Results
of testing A. diaperinus from the only south east Queensland egg
barn studied show that the insects are still susceptible to fenitrothion
and a rotation of fenitrothion and cyfluthrin may be done on alternate
clean outs. Whether these egg barn results are typical for all is
not known.
For broiler sheds in general it is suggested that the application of cyfluthrin may be reduced to every second clean out (part or full) or just used over the summer period. This may delay the development of stronger resistance. Preliminary results for the broiler production areas of Armidale and the Atherton Tablelands indicate that fenitrothion may be included with cyfluthrin in an insecticide rotation. In summary, as development
of strong insecticide resistance in all areas is inevitable given time,
a closer examination is needed of the other major factors that control
population sizes in broiler sheds. When this is known, studies of
currently registered insecticides, alternative control strategies and the
interaction of both can be properly evaluated.
|
Publications |
Lambkin,
T.A. (1998) Controlling black beetles (Alphitobius diaperinus) in
chicken sheds. Proceedings 1998 Poultry Exchange Surfers Paradise
19-21 April 1998, 33-37.
Lambkin, T.A. and Cameron, M.C. (1999) Darkling beetle control-current difficulties and future prospects. Proceedings 11th Australian Poultry & Feed Convention 10-13 October 2000,184-192. Lambkin, T.A. & Cameron, M.C. (2000) Darkling beetle control in Australian broilers - a new direction. Proceedings 2000 Poultry Exchange Surfers Paradise 9-11 April 2000, 97-102. |
| Project Title | The efficient production of big liver and spleen vaccine antigen |
| RIRDC Project No: | DAW-98A |
| Researcher: | Dr Sarah Plant |
| Organisation: | Agriculture
Western Australia
3 Baron Hay Court SOUTH PERTH WA 6151 |
| Phone: | (08) 9368 3873 |
| Fax: | (08) 9474 2408 |
| Email: | splant@agric.wa.gov.au |
Objectives |
·
To assess alternative methods of BLS antigen production.
·
To reduce the financial losses associated with BLS through the development
and assessment of efficient techniques for the production of BLS vaccine
antigen.
|
Background |
Earlier RIRDC-funded projects developed highly specific and sensitive diagnostic tests for big liver and spleen (BLS) infection and identified a candidate vaccine for BLS disease of broiler breeder hens. The vaccine was shown to generate a satisfactory response to BLS and vaccinated birds demonstrated the ability to clear a BLS infection faster than unvaccinated birds. The production of this vaccine is cumbersome and not economically suitable for large scale commercialisation. |
Research |
Two
methods of producing a less expensive BLS vaccine were examined.
One method used a small protein (peptide) selected for its antigenic similarity
to the BLS protein (phage library). This peptide was expressed on
a bacteriophage (bacterial virus) which was simple and inexpensive to produce
in large quantities. The second method attempted to express the BLS
protein in an insect cell culture system.
The bacteriophage-expressed
protein was inoculated into hens as a synthetic peptide and as expressed
on the bacteriophage in a small-scale vaccine trial, where antibody responses
were monitored.
|
Outcomes |
A peptide was identified which had antigenic similarity with the BLS protein. Hens inoculated with a synthetic preparation of this peptide demonstrated increased antibody titres to the peptide following inoculation. This increase in antibody titre was not observed in hens inoculated with the peptide expressed on the bacteriophage. No BLS protein was produced in the insect cell culture system. |
Implications |
This project showed that the bacteriophage system selected peptides with antigenic similarity to the BLS protein. The vaccine study also showed encouraging antibody responses in the synthetic peptide inoculated birds. Future work should determine if the vaccinated birds demonstrate an improved ability to clear BLS viral infection. The peptide vaccine may represent a more cost-effective means of BLS vaccine production. |
| Project Title | The development of effective immunisation strategies against Marek’s disease |
| RIRDC Project No: | RMI-6J |
| Researcher: | Prof Greg Tannock |
| Organisation: | RMIT
University
Virology Laboratory PO Box 71 BUNDOORA VIC 3083 |
| Phone: | (03) 9925 7142 |
| Fax: | (03) 9925 7110 |
| Email: | gtan@rmit.edu.au |
Objectives |
·
To improve the performance of existing Marek’s disease vaccines using suitable
adjuvants.
· To characterise MDV strains after adaptation to continuous cell lines. · To develop
a MDV serotype 1 specific probe to use in a dot-blot hybridisation technique.
|
Background |
For
almost 30 years, Marek’s disease (MD) has been largely controlled by the
use of intensive vaccination with herpesvirus of turkeys (HVT), either
alone or in combination. However, in recent years HVT vaccines have
shown to be much less effective against emerging field strains of MDV of
increasing virulence.
Adjuvants are used to improve the immunogenicity of a vaccine without increasing the amount of infectious virus in the vaccine. An adjuvant enhancing the performance of the HVT vaccine would be a value-added benefit to a cheap and readily available existing vaccine. The adaptation of MDVs to growth in a continuous cell line could be useful for vaccine production, compared with the labour and reagent intensive CEF cultures that are currently used. Because of limitations associated
with current detection techniques for MDV serotype 1 virus, a MDV1 specific
probe used in a rapid identification assay which is less expensive and
more specific than those currently available, would be very useful for
field diagnosis and important in vaccine evaluation.
|
Research |
Commercial
broiler chickens were used to assess the possible role of g-inulin as an
adjuvant to improve the efficiency of HVT vaccination against MD.
Chickens were administered vaccine with or without g-inulin using three
vaccination procedures: (i) in-ovo, by InovojectÒ, (ii) in
ovo by hand, or (iii) subcutaneously (sc) at day old. All birds
were challenged with a virulent MDV 1 challenge virus at three days of
age. Effective vaccination by HVT was assessed by the development of viraemia.
HVT and MDV1 were adapted to the Vero continuous cell line (Jaikumar, 2001) and were characterised by immunological and molecular techniques. A probe labelled with digoxigenin
(DIG) was developed for the detection of MDV 1 by dot-blot hybridisation.
The probe was labelled by the incorporation of DIG in a PCR reaction
product that consisted of the amplified 132 bp repeat located within the
inverted repeat long region of the MDV 1 genome. The sensitivity and specificity
of virus isolation and dot-blot hybridisation were compared with PCR, which
was used as the reference procedure.
|
Outcomes |
In
the vaccination trial, MD was present in all treatment groups but its incidence
in groups treated with g-inulin was not significantly different from non-treated
groups. Differences in the percentages of MD in groups administered
g-inulin using the InovojectÒ method or sc at day 1 were also non-significant.
No adverse effects due to g-inulin were noted in any group.
HVT grew more rapidly and produced more extensive CPE and higher virus yields in Vero cell lines than MDV1. When the genome of adapted serotype 1 viruses was examined, an expansion of the 132 bp DR sequence indicated that the infected cell line contained serotype 1 MDV DNA. The presence of intact DNA with a size of approximately 180 kb in both serotype 1- and HVT-infected Vero cells after isolation and characterisation indicated that whole copies of both types of DNA were present and provided further evidence for adaptation to growth of the serotype 1 virus. This is the first report of the growth of either virus in a continuous line. Highest sensitivity rates
were achieved by dot-blot hybridisation using the 132 bp PCR probe, compared
with virus isolation and identification by immunoperoxidase or immunofluorescence.
Despite their much lower sensitivity, higher specificity was obtained by
both culture detection methods than for the dot-blot hybridization
|
Implications |
This
project has shown that g-inulin did not appear to function as an adjuvant
when administered with HVT vaccine. The presence of intact DNA with
a size of approximately 180 kb in both serotype 1- and HVT-infected Vero
cells after isolation and subsequent analysis in a pulsed-field gel indicates
that whole copies of both types of DNA were present and provides further
support for adaptation to growth of the serotype 1 virus, thus would be
useful for new and improved vaccine production procedures.
The dot-blot hybridisation
technique using the DIG-labelled probe specific for MDV 1 was shown to
be potentially very useful as a rapid and economical test to detect MDV.
|
Publications |
Cipriani,
T. L. (2000) The development of two digoxigenin-labelled probes for the
detection of Marek’s disease virus by dot-blot hybridisation. B. App.Sc.Honours
Thesis.
Jaikumar, D. (1998) Propagation and molecular characterisation of Marek’s disease virus. Master of App.Sc. Thesis. Jaikumar, D. (2001) Adaptation of Marek’s disease virus to the Vero continuous cell line. Veterinary Microbiology 70, 75-82. |
| Project Title | Characterisation of very virulent Australian isolates of Marek’s disease virus |
| RIRDC Project No: | RMI-8J |
| Researcher: | Prof Greg Tannock |
| Organisation: | RMIT
University
Virology Laboratory PO Box 71 BUNDOORA VIC 3083 |
| Phone: | (03) 9925 7142 |
| Fax: | (03) 9925 7110 |
| Email: | gtan@rmit.edu.au |
Objectives |
·
To collect and maintain a repository of serotype 1 strains of Marek’s disease
virus (MDV) representative of Australia and to characterise them for future
reference.
· To determine optimum methods for standardising Marek’s disease (MD) vaccines. · To prepare and maintain reference preparations of NDV for use in vaccine assays. · To provide an independent, reliable vaccine assay facility for use by Australian vaccine manufacturers in harmony with requirements set by NATA. · To continually
maintain and supply MDV challenge preparations for use by the industry.
|
Background |
MD is currently a significant economic problem for the Australian chicken industry. Current, locally developed vaccines appear to provide very little protection against recently isolated very virulent strains of MDV. The availability of new vaccines increases the need for a reliable assay system to evaluate their effectiveness. Previously, vaccine assays were carried out by individual manufacturers without access to standard reference preparations. A repository will allow study trends in the evolution of MDV to be studied. |
Research |
Blood
samples were collected from flocks in different parts of the country that
have been experiencing MD losses. These samples were screened for
the presence of serotype 1 MDV. Positive samples were stored in liquid
nitrogen for future reference.
In consultation with vaccine manufacturers and industry representatives, the Virology Laboratory set up a vaccine assay facility and is seeking accreditation with the National Association of Testing Authorities (NATA). During the establishment phase of the assay, a nominal cell count and virus titre, with maximum and minimum limits, were set for two reference preparations and were revised after their substantial use to monitor the stability of the assay. Studies were carried out
in response to industry concerns about possible losses to vaccine potency
from the widely used practice of using chilled diluent whilst administering
vaccines. Another study assessed the differences between operators
whilst performing vaccine assays.
|
Outcomes |
Some
300 blood samples were collected, of which 86 were positive for serotype
1 MDV. Characterisation studies did not commence within the project’s
time frame. However, despite their pre-characterisation status, the
samples remain as a viable repository of MDV isolates and will be available
for comparative purposes in the future.
A liquid overlay procedure was adopted for the vaccine assay and over 1000 assays have been conducted since the establishment of the facility in January 1998. Few manufacturers have used the facility despite its availability to all Australian manufacturers. An impending move to a new purpose-built facility and its audit, will take place before registration with NATA. The revised cell count and
virus titre results indicated the stability of each reference preparation
and thus validated the nominal virus titres used throughout the assay procedure.
The use of diluent held at room temperature substantially decreases virus
titre loss (as opposed to holding diluent at 4°C). Therefore,
it is critical to maintain diluent at room temperature whilst administrating
MD vaccines to maintain their potency. Differences in vaccine titre
of parallel assays of two operators were non significant and, consequently,
did not affect the assay result.
|
Publications |
Two presentations on the functions of the vaccine assay facility were given at meetings of the Australian Veterinary Poultry Association at Surfers’ Paradise in April 1999 and the Victorian Poultry Health and Welfare Liaison Group in September 1999. |
| Project Title | Candidate vaccine antigens against Pasteurella multocida |
| RIRDC Project No: | UMO-21A |
| Researcher: | Prof Ben Adler |
| Organisation: | Monash
University
Department of Microbiology Wellington Road CLAYTON VIC 3800 |
| Phone: | (03) 9905 4815 |
| Fax: | (03) 9905 4811 |
| Email: | ben.adler@med.monash.edu.au |
Objectives |
·
To evaluate the potential of genes of Pasteurella multocida as candidates
for attenuating mutations for the construction of live vaccines.
· To assess the capacity of expressed recombinant antigens to protect against infection in chickens. ·
To make recommendations with respect to vaccine choice and development
against fowl cholera.
|
Background |
Fowl cholera caused by infection with the bacteria P. multocida is a cause of economic loss in the poultry industry in Australia and other countries. Available vaccines are undefined, empirically derived and of variable efficacy. There is a lack of knowledge of the basic mechanisms of immunity and pathogenesis (ability to cause disease) in P. multocida infections. |
Research |
Several
candidate antigens of P. multocida were expressed in recombinant
form, purified and then tested for their ability to stimulate immunity
against infection in the mouse model and in the natural chicken host. The
outer-most component of the bacterial surface (termed the capsule) is critical
in allowing bacteria to cause infection. The role of capsule in P. multocida
infection and immunity was evaluated by the construction of defined acapsular
mutants.
|
Outcomes |
Levels of immunity varied widely depending upon the antigen studied. The best prospect for a vaccine antigen appears to be the outer membrane protein Oma87. The capsule of P. multocida was shown to be a key virulence factor. Immunity could be stimulated by acapsular bacteria, indicating that recombinant vaccines based on protein antigens are feasible. |
Implications |
The project has shown that it is possible to stimulate protective immunity against fowl cholera with either recombinant outer membrane proteins or with genetically attenuated bacteria. Further research is required for detailed evaluation of these approaches. |
Publications |
Hunt,
M.L., Boucher, D.J., Boyce, J.D. and Adler, B. (2001) In vivo expressed
genes of Pasteurella multocida. Infect. Immun. In Press.
Chung, J.Y., Wilkie, I., Boyce, J.D., Townsend, K.M., Frost, A.J. and Adler, B. (2001) The role of capsule in the pathogenesis of fowl cholera caused by Pasteurella multocida serogroup A. Infect. Immun. In Press. |
|
|
Boyce,
J.D. and Adler, B. (2001) Acapsular Pasteurella multocida B:2 can
stimulate protective immunity against pasteurellosis. Infect. Immun.
69, 1943-1946.
Townsend, K.M., Chung, J.Y., Boyce, J.D., Frost, A.J. and Adler, B. (2001) Genetic organisation of all Pasteurella multocida cap loci and its application in the development of a multiplex PCR typing system. J Clin Microbiol. In Press. Hunt, M.L., Cox, A.J., Ruffolo, C.G., Rajakumar, K. and Adler, B. (2000) Characterisation of a Pasteurella multocida esterase gene which confers a haemolytic phenotype in Escherichia coli under anaerobic conditions. FEMS Microbiol. Lett. 192, 249-256. Boyce, J.D. and Adler, B. (2000) The role of capsule in the pathogenesis of Pasteurella multocida B:2. Infect. Immun., 68, 3463-3468. Boyce, J.D., Chung, J.Y. and Adler, B. (2000) Pasteurella multocida capsule: composition, function and genetics. J Biotechnol. 83, 153-160. Boyce, J.D., Chung, J.Y. and Adler, B. (2000) Genetic organisation of the capsule biosynthetic locus of Pasteurella multocida M1404 (B:2). Vet Microbiol., 72, 121-134. Mitchison, M., Wei, L., Kwang, J., Wilkie,I. and Adler, B. (2000) Overexpression and immunogenicity of the Oma87 outer membrane protein of Pasteurella multocida. Vet Microbiol., 72, 91-96. Doughty, S.W., Ruffolo, C.G. and Adler, B. (2000) The type 4 fimbrial subunit gene of Pasteurella multocida, Vet Microbiol., 72, 79-90. Cox, A., Ruffolo, C.G. and Adler, B. (2000) A Pasteurella multocida gene, ahpA, which confers haemolytic phenotype upon Escherichia coli. Vet Microbiol., 72, 135-152. Hunt, M.L., Adler, B. and Townsend, K.M. (2000) The molecular biology of Pasteurella multocida. Vet Microbiol., 72, 3-25. Adler, B., Bulach, D., Chung, J., Doughty, S., Hunt, M., Rajakumar, K., Serrano, M., van Zanden, A., Zhang, Y. and Ruffolo, C. (1999) Candidate vaccine antigens and genes in Pasteurella multocida. J Biotechnol., 73, 83-90. Chung, J.Y., Zhang, Y., Adler, B. (1998) The capsule biosynthetic locus of Pasteurella multocida A:1. FEMS Microbiol. Lett., 166, 289-296. |
| Project Title | Effects of enzymes on gut microbial status in broiler chickens |
| RIRDC Project No: | UNE-70A |
| Researcher: | Dr Mingan Choct |
| Organisation: | University
of New England
School of Rural Science and Natural Resources - Animal Science ARMIDALE NSW 2351 |
| Phone: | (02) 6773 5121 |
| Fax: | (02) 6773 3275 |
| Email: | mchoct@metz.une.edu.au |
Objective |
· To identify opportunities for using commercial enzymes in broilers to modify gut microbial status in a beneficial way to the host, in particular, in reduction of Clostridium perfringens. |
Background |
Broilers fed diets based on viscous grains such as wheat and barley appear to be more prone to necrotic enteritis than those fed non-viscous cereals such as corn and sorghum. It is hypothesised that the soluble non-starch polysaccharides (NSP) create a gut environment which encourages the proliferation of Clostridium perfringens, the causative agent for necrotic enteritis. Degradation of the NSP using enzymes thus may disrupt this environment, leading to reduced risk of necrotic enteritis outbreak. |
Research |
A number of experiments was conducted to induce necrotic enteritis under experimental conditions and to examine the effect of xylanase supplementation on the gut microflora, including C. perfringens in broilers fed wheat based diets. |
Outcomes |
Introduction
of a low metabolisable energy (ME) wheat diet at the end of the starter
phase of broilers led to a large increase in the number of C. perfringens.
Xylanase supplementation markedly reduced the number of C. perfringens both in the ileum and the caeca. An experimental model system
to induce necrotic enteritis required inoculation of both Eimeria spp
and C. perfringens. The success rate of such a model was at
best 60%.
|
Implications |
Change of diet at the end of the starter phase without antibiotics will leave the birds highly susceptible to an outbreak of necrotic enteritis. Use of appropriate enzymes may alleviate this problem should restrictions on the use of antibiotics in feed be implemented. |
| Project Title | Postgraduate scholarship – David Witcombe: Production and characterisation of recombinant antigens of Eimeria |
| RIRDC Project No: | UTS-3J |
| Researcher: | Mr David Witcombe and Nicholas Smith |
| Organisation: | University
of Technology
Molecular Parasitology Unit Dept of Cell and Molecular Biology PO Box 123 BROADWAY NSW 2007 |
| Phone: | (02) 9514 4013 |
| Fax: | (02) 9514 4026 |
| Email : | Nick.Smith@uts.edu.au |
Objectives |
·
To prepare recombinant versions of a putative subunit vaccine candidate
from Eimeria, the 230 kDa merozoite protein.
· To explore the potential molecular relationships between this protein and gametocyte proteins of Eimeria. · To determine the importance of glycosylation of these proteins for induction of immunity. · To determine how the genes encoding these antigens are organised and expressed in the genome and whether they undergo antigenic variation or diversification. ·
To assess whether combination immunoprophylaxis (eg vaccination with merozoite
and gametocyte antigens) is more efficacious than vaccination with antigens
from one developmental stage alone.
|
Background |
Coccidiosis,
caused by the protozoan parasite, Eimeria, is a major pathogenic
disease of poultry worldwide. Coccidiosis costs the poultry industry
internationally over $1 billion per year. The resistance of the parasite
to anticoccidials, the high cost of development of new anticoccidials and
the demands by the public for chemical-free meat drive the quest for a
vaccine to control coccidiosis.
Young chickens are protected against Eimeria by the transfer of antibodies from their mothers into the egg yolk, which is absorbed by hatchlings. These maternal antibodies have been used to identify proteins for inclusion in a vaccine. Exploration into the molecular
composition of these proteins of Eimeria will allow deduction of
the minimal components required for an effective vaccine. The development
of a maternally-delivered vaccine against coccidiosis will benefit the
poultry industry by allowing reduced use of chemotherapy, potentially effecting
a significant cost reduction and satisfying consumer demand for residue-free
meat.
|
Research |
The
230 kDa merozoite antigen of Eimeria maxima has been purified and
N-terminal and internal tryptic digest amino-acid sequences determined.
Using these sequences, the genetic code for the protein has been determined.
Expression and production of recombinant proteins are underway.
The sequences of gametocyte antigens (amino acid and genetic sequences) do not appear to be related to the sequence of the 230kDa protein. There are several potential glycosylation sites in the 230 kDa merozoite protein. Similar sequences appear to be found in several species of Eimeria. Immunogenicity and efficacy
trials using purified native and recombinant versions of the 230 kDa E.
maxima merozoite protein will commence shortly.
|
Implications |
The results obtained to date suggest that the 230 kDa protein of E. maxima is a stage-specific molecule (found in asexual stages only). However, the observation that this protein is present in more than one species of Eimeria suggests that it has some conserved and important function in the development of the parasite. Therefore, it is a logical target for use in a subunit vaccine against coccidiosis. |
Publications |
Witcombe,
D., Belli, S., Wallach, M. and Smith, N. (2000) Western blot analyses and
purification of an immunodominant asexual stage protein from Eimeria
maxima. New Zealand and Australian Societies for Parasitology, Annual
Scientific and General Meeting, Wellington, September.
Belli, S., Witcombe, D., Padula, M., Wallach, M. and Smith, N. (1999) The use of SDS-PAGE and 2-D PAGE in the analysis of parasite derived antigens. Australian Electrophoresis Society Sixth Annual Conference, Melbourne, October. Witcombe, D., Belli, S., Wallach, M. and Smith, N. (1999) Characterisation of an immunodominant merozoite antigen from Eimeria maxima. Vaccines Against Animal Coccidioses, Interlaken, Switzerland, November. |
Bird Nutrition and Feed
Supply
| Project Title | Premium Grains for Livestock Program |
| RIRDC Project No: | GRD-1J |
| Researcher: | Dr John Black |
| Organisation: | John
L Black Consulting
Locked Bag 21 WARRIMOO NSW 2774 |
| Phone: | (02) 4753 6231 |
| Fax: | (02) 4753 6295 |
| Email: | jblack@pnc.com.au |
Objectives |
·
To identify the reasons for and magnitude of differences between grains
in their nutritional value for ruminants, pigs and poultry so that improvements
in grain quality can be achieved by plant breeding and through grain processing
and storage.
· To develop rapid tests, suitable for the site of grain receipt and/or use, to measure the nutritional value of grains so that they can be priced in accordance with their suitability as an animal feed. ·
To develop a computer simulation model for ruminants to predict accurately
the consequences of grain characteristics and of grain processing and storage
on the productivity of feedlot cattle.
|
Background |
The
Program involved collaborative funding from the Grains, Pig and Dairy R&D
Corporations, Meat and Livestock Australia and the Chicken Meat and Egg
Programs of RIRDC.
The Program is expected to
improve the quality of grains available to the animal industries and to
provide a more rational basis for trading feed grains based on measurement
of the nutritional characteristics of grains determining their quality
for different livestock enterprises.
|
Research |
Over
2000 grain samples covering the widest possible range in chemical and physical
characteristics that may influence animal performance have been collected.
The samples have been derived from germplasm collections, plant breeders,
specially grown crops and commercial grains suspected of having extremes
in nutritional values because of severe drought, frost damage or germination.
All samples collected have been scanned with near infrared spectrometry
(NIR). Approximately 115 analyses of chemical and physical characteristics
thought to influence nutritional value have been conducted on all grains
fed to animals. These involved analyses for individual carbohydrate,
fatty acid and amino acid components, a- and b-amylase and anti-nutritional
factors such as lectins, tannins and phytic acid. Physical properties
included measurement of grain weight, hydration capacity, seed colour,
seed diameter, seed size distribution, seed hardness index and profile,
and the viscosity of whole grain, starch extract and acid soluble extract.
Light and electron microscopy has been used to examine the physical structure
of some grains that differ markedly in their nutritional value.
Many grains, including all those fed to animals have been examined using in vitro systems simulating both rumen fermentation and intestinal digestion. These analyses have been extremely useful for identifying grains that potentially have large differences in nutritional value for different classes of livestock and for screening potential processing procedures. A relatively small number of grains (approximately 100) covering the range identified in chemical and physical characteristics have been fed to sheep, cattle, pigs, broiler chickens and laying hens to determine the digestion of energy, individual grain compounds and, in some animal species, amino acids. The effects of processing and storage on the nutritional value of grain for different animal species have been evaluated using the in vitro systems. Development of rapid and
accurate analytical tests for measuring the most important chemical and
physical characteristics that determine nutritional value of feed grains
has commenced. Preliminary analyses using NIR have been developed
for predicting the digestible energy content of grains for pigs, apparent
metabolisable energy (AME) for broiler chickens and whole animal dry-matter
digestibility for sheep. In addition, NIR procedures have been used
for predicting the major chemical components of grains and for predicting
the in vitro digestion of various grain components.
|
Outcomes |
Results show that there is a wide variation in energy availability both within and between cereal grain species and between animal types. For example, the observed range in AME (MJ/kg) for broiler chickens for the grains examined in the Program is 15.4-16.1 for sorghum, 13.2-14.7 for wheat, 11.2-13.2 for barley, 11.2-14.4 for triticale, 12.6-13.4 for normal oat grain and 14.6 for naked oats. Naked oats had an AME value of 16.2 for laying hens. Sorghum has a much lower available energy content for cattle at 9.7 MJ/kg than for pigs (14.6 MJ/kg) or broiler chickens (15.9 MJ/kg). The energy value of waxy sorghum is enhanced considerable for cattle to 13.2 MJ/kg, but there was only a marginal increase of 0.1 to 0.5 MJ/kg for pigs and poultry. |
Implications |
Several
hypotheses about the factors determining the nutritional value of cereal
grains for different animal types have been established and are being evaluated
in the current Project GRD-3J.
|
Publications |
Balogun,
R., Bird, S. H. and Rowe, J. B. (2000) Improving the nutritive value of
sorghum grain by germination. Asian-Australian Journal of Animal
Science. 13 (supp): 160.
Bird, S. H., Rowe, J. B., Choct, M., Stachiw, S., Tyler, P. and Thompson, R. D. (1999) In vitro fermentation of grain and enzymatic digestion of starch. Recent Advances in Animal Nutrition in Australia (Editor J. L. Corbett), 12: 53-61. Black, J. L. (1999) Nutritional value of cereal grains for animals. Chemistry in Australia. 66: 7-9. Black, J. L. (1999) The Premium Grains for Livestock Program. In: The Eleventh Australian Poultry & Feed Convention, Royal Pines Resort Gold Coast, Australia. pp. 226-32. Black, J. L. (2001) Variation in nutritional value of cereal grains across livestock species. Australian Poultry Science Symposium, University of Sydney, Sydney, Australia 13: 22-9. |
|
|
Choct,
M., Hughes, R. J., Perez-Maldonado, R. and van Barneveld, R. J. (2001)
The metabolisable energy value of sorghum and barley for broilers and layers.
Australian
Poultry Science Symposium, University of Sydney, Sydney, Australia
13:
39-42.
Dixon, R. M. and Stockdale, C. R. (1999) Associative effects between grains and forages: consequences for feed utilisation. Australian Journal of Agricultural Research50: 757-73. Evers, A. D., Blakeney, A. B. and O’Brien, L. (1999) Cereal structure and composition. Australian Journal of Agricultural Research. 50: 629-50. Farrell. D. J. (1999) In vivo and in vitro techniques for the assessment of the energy content of feed grains for poultry: a review. Australian Journal of Agricultural Research 50: 881-8. Flinn, P. C. (2000) Current and potential use of NIR in the fodder and grain industries: a ruminant’s perspective. In: Reading more from the spectrum, 9th Australian Near Infrared Spectroscopy Conference, Horsham, VIC, Apr 2000. Flinn, P. C. (2000) Rapid methods for the quality assessment of grains for animal nutrition. In: Chemical aspects of grain in human and animal nutrition., Cereal Chemistry Division Symposium, 11th RACI Convention, Canberra, ACT, Feb 2000, p15. Flinn, P. C., Heazlewood, P. G. and Dalton, S. L. (2000) Recent developments in improving the prediction of digestibility of feed grains. In: 9th International Conference on Near Infrared Spectroscopy Verona, Italy, Jun 1999 (in press). Hogan, J. P. and Flinn, P. C. (1999) An assessment by in vivo methods of grain quality for ruminants. Australian Journal of Agricultural Research 50: 843-54. Hughes, R. J. and Choct, M. (1999) Chemical and physical characteristics of grains related to variability in energy and amino acid availability in poultry. Australian Journal of Agricultural Research 50: 689-701. Hughes, R. J., Choct, M. and van Barneveld, R. J. (2001) Factors influencing the energy values of Australian cereal grains fed to broilers. Australian Poultry Science Symposium, University of Sydney, Sydney, Australia 13: 30-8. Kaiser, A. G. (1999) Increasing the utilisation of grain when fed whole to ruminants. Australian Journal of Agricultural Research. 50: 737-56. Kitessa, S., Flinn, P. C. and Irish, G. G. (1999) Comparison of methods used to predict the in vivo digestibility of feeds in ruminants: A review. Australian Journal of Agricultural Research 50: 825-41. Kruk, J. A. and van Barneveld, R. J. (1999) Near infra-red spectrophotometry predictions of digestible energy in cereals for pigs. In: Manipulating Pig Production VII (submitted, Editor P. D. Cranwell) Australasian Pig Science Association, Werribee, VIC. Nagorka, B. N. (2000) A ruminant model to estimate the nutritive value of grains in cattle feedlots. International Report, CSIRO CLI. Nagorka, B. N., Gordon, G. L. R. and Dynes, R. A. (2000) Towards a more accurate representation of fermentation in mathematical models of the rumen. Modelling Nutrient Utilization in Farm Animals (Editors McNamara, J. P., France, J. and Beever, D. E.) CAB International, London (in press). Moughan, P. J. (1999) In vitro techniques for the assessment of the nutritive value of feed grains for pigs: a review. Australian Journal of Agricultural Research 50: 871-9. O’Brien, L. (1999) Genotype and environment effects on feed grain quality. Australian Journal of Agricultural Research. 50: 703-19. O’ Brien, L. (2000) Genotype and environment effects on feed grain quality. Royal Chemical Institute, 11th National Convention, Canberra, ACT, Feb 2000. O’Brien, L. and Blakeney, A. B. (2000) Genetic variation for components of dietary fibre in wheat and barley grains. 11th Cereals and Bread Congress, Gold Coast, Sept 2000. O’Brien, L. and Blakeney, A. B. (2000) Opportunities for genetically improving the dietary fibre content of wheat and barley. International Dietary Fibre Congress, Dublin, Ireland, May 2000. |
|
|
O’Brien,
L., Tredea, A. M., van Barneveld, R., Bird, S. and Rowe, J. (2000) Genotype
and environment effects on measures of feed grain quality in wheat, barley
and oats. 11th Cereals and Bread Congress, Gold
Coast, Sept 2000.
Petterson, D. S., Harris, D. J., Rayner, C. J., Blakeney, A. B. and Choct, M. (1999) Methods for the analysis of premium livestock grains. Australian Journal of Agricultural Research 50: 775-87. Ravindran, V. and Bryden, W. L. (1999) Amino acid availability in poultry – in vitro and in vivo measurements. Australian Journal of Agricultural Research50: 889-908. Rowe, J. B., Choct, M. and Pethick, D. W. (1999) Processing cereal grains for animal feeding. Australian Journal of Agricultural Research 50: 721-36. van Barneveld, R. J. (1999). Chemical and physical characteristics of grains related to variability in energy and amino acid availability in pigs: a review. Australian Journal of Agricultural Research 50: 667-87. van Barneveld, R. J. (1999) Controlling the nutritional quality of stockfeed ingredients. VICTAM Feed Ingredients and Grain Processing Asia ’99. Bangkok, Thailand, 3-5 November, 1999. van Barneveld, R. J. (1999) Physical and chemical contaminants in grains used in livestock feeds. Australian Journal of Agricultural Research 50: 807-23. van Barneveld, R. J. (1999) Strategies for the assessment of livestock feed ingredient quality. Recent Advances in Animal Nutrition in Australia 12: 63-72. van Barneveld, R. J., Ru, Y. J., Wyatt, G. F. and Pluske, J. R. (2000) Relationship between the ileal and faecal digestible energy content of pig diets containing Australian barley cultivars. Proceedings of the Nutrition Society of Australia (in press). van Barneveld, R. J., Ru, Y. J., Szarvas, S. R. and Wyatt, G. F. (1999) Range in digestible energy and true ileal digestible lysine content of 11 barley samples. In: Manipulating Pig Production VII (submitted, Editor P. D. Cranwell) Australasian Pig Science Association, Werribee, VIC. van Barneveld, S. (1999) Chemical and physical characteristics of grains related to variability in energy and amino acid availability in ruminants: a review. Australian Journal of Agricultural Research 50: 651-66. White, C.L. and Ashes, J. R. (1999) A review of methods for assessing the protein value of grain fed to ruminants. Australian Journal of Agricultural Research50: 855-69. Wrigley, C. M. (1999) Potential methodologies and strategies for the rapid assessment of feed-grain quality. Australian Journal of Agricultural Research 50: 789-805. Zarrinkalam, M. R., van Barneveld, R. J., Tivey, D. R. and Choct, M. (1999 Predicting energy availability in barley for pigs and poultry using rapidly determined fibre content. In: Manipulating Pig Production VII (submitted, Editor P. D. Cranwell) Australasian Pig Science Association, Werribee, Vic. |
| Project Title | Postgraduate scholarship- Andreas Kocher: Increasing the nutritive value of grain legumes for poultry by use of more efficacious enzyme systems |
| RIRDC Project No: | UNE-64A |
| Researcher: | Mr Andreas Kocher and Dr Mingan Choct |
| Organisation: | Universtiy
of New England
School of Rural Sciences ARMIDALE NSW 2350 |
| Phone: | (02) 6773 5121 |
| Fax: | (02) 6773 3275 |
| Email: | akocher2@metz.une.edu.au |
Objective |
· To investigate the effect of commercial feed enzymes on the nutritive value of grain legumes. |
Background |
Grain
legumes and oilseed meals are already widely used as the main protein source
in pig and poultry diets. However, the high content of indigestible
carbohydrates such as oligosaccharides and non-starch polysaccharides (NSP)
in these ingredients will reduce their nutritive value for broiler chickens.
In diets based on wheat and barley, high levels of soluble NSP raise digesta
viscosity in the intestine of chickens leading to reduced starch, protein
and lipid digestion.
The addition of commercial
feed pentosanases and b-glucanases to these diets generally results in
a significant reduction in intestinal viscosity and subsequently in an
increase in growth performance. There is only limited documentation
available on the anti-nutritive effects of NSP in legumes and oilseed meals
and the possible benefits from the addition of commercial feed enzymes.
The objectives of the work reported in this PhD project were to investigate
the effects of commercial feed enzymes on the nutritive value of vegetable
proteins. In particular, this study has focused on the effects of
feed enzymes on the utilisation of neutral non-starch polysaccharides of
lupins, soybean, canola and sunflower seeds.
|
Research |
A
preliminary study investigated the effects of feed enzymes designed to
hydrolyse NSP in vegetable proteins on the utilisation of NSP in a low
NSP cereal (sorghum). In four separate studies the effects of commercial
enzyme products on the nutritive value of lupins (L. angustifolius and
L. albus), canola meal, sunflower meal and soyabean meal were investigated.
These studies were designed to determine the effects of enzyme addition
on the performance and nutrient utilisation of broilers, as well as on
the composition of NSP in the jejunum and ileum of broilers fed diets containing
a minimum of 35% legumes with or without enzyme supplementations.
|
Outcomes |
The
addition of commercial feed enzymes designed to utilise NSP of legumes
had no effects on broiler performance, apparent metabolisable energy (AME)
and the composition of NSP in the intestine of broilers fed a sorghum/casein
basal diet. It was concluded that, in future experiments, any differences
between diets with or without enzymes would be entirely due to the vegetable
protein component.
In diets with L. Angustifolius the addition of enzymes with a high level of polygalacturonase activity significantly (P<0.001) raised digesta viscosity and increased the concentration of soluble NSP in all sections of the intestine. The structures of NSP isolates from ileal digesta were characterised using size-exclusion chromatography and 1H-NMR spectroscopy. The structural composition of isolates obtained from diets with or without enzyme supplementation revealed that the enzyme solubilised parts of the pectic backbone, most likely the main pectic polymer, rhamnogalacturonan in lupins. The actual cleavage point of the enzyme was found to be in the less branched regions of the pectic backbone. Enzymes tended to reduce
the water-soluble NSP fraction in the upper intestine of broilers fed diets
high in canola meal, sunflower meal and soya bean meal. However,
only the addition of these enzymes at a very high dosage (five times the
recommended dosage) led to a significant (p<0.05) improvement in AME
and nutrient digestibility. Benefits of enzyme addition to commercially
formulated broiler diets with high levels of canola meal were found in
improved drip loss, dress yield and breast meat.
|
Implications |
Commercial
feed enzymes with increased polygalacturonase activities have noticeable
effects on the carbohydrate components of the vegetable proteins.
However, actual commercial benefits were only evident when enzymes were
added at very high dosage level (five times the recommended dosage).
The results of this project
demonstrated that soluble NSP of vegetable proteins do not exhibit strong
anti-nutritive effects and can be largely utilised throughout the gut by
microbial digestion. The benefit of feed enzyme addition lies in
the increase in efficiency of using NSP as energy sources in broiler diets.
The depolymerisation of pectins by exogenous enzymes in the upper intestine
will give the bird access to intracellular entrapped nutrients as well
as provide a more efficient energy utilisation.
|
Publications |
Kocher,
A., Hughes, R.J., Choct, M. and Broz, J. (2000) Effect of food enzyme addition
on utilisation of lupin carbohydrates by broilers. British Poultry
Science, 41: 75-82.
Kocher, A. and Choct, M. (2000) Enzyme supplementation of diets containing high levels of legumes. Proceedings of the 12th Australian Poultry Science Symposium, 12: 159-163. Kocher, A. and Choct, M. (2000) Lupin non-starch polysaccharides: Utilisation by chickens in the presence of feed enzymes. Dietary Fibre 2000, Dublin Ireland, p. 105. Choct, M. and Kocher, A. (2000) Use of enzymes in non-cereal grain feedstuff. Proceedings of the World Poultry Science Congress, 11: S1.10.04. Choct, M. and Kocher, A. (2000) Non-starch polysaccharides: Digestion and its secondary effects in monogastrics. Proceedings of the 24th annual scientific meeting of the Nutrition Society of Australia, 24: 31-38. Kocher, A., Choct M., Porter, M.D. and Broz, J. (2000) The effects of enzyme addition to broiler diets containing high levels of canola and sunflower meal. Poultry Science, 79: 1767-1774. Kocher, A. and Choct, M. (2001) Do enzymes improve the nutritive value of soybeans in broiler diets? Proceedings of the 13th Australian Poultry Science Symposium 13:204-207. Kocher, A., Choct, M., Morrisroe, L. and Broz, J. (2001) Effects of enzyme supplementation on the replacement value of canola meal for soybean meal in broiler diets. Australian Journal of Agricultural Research, 54: 447-452. |
|
|
|
|
|
Kocher,
A., Choct, M., Porter, M.D. and Broz, J. (2001) Effect of food enzyme addition
on utilisation of soybean carbohydrates by broiler. British Poultry Science,
(in press).
Kocher, A. (2001) Enzymatic Degradation of Non-Starch Polysaccharides in Vegetable Proteins in Poultry Diets. Recent Advances in Animal Nutrition in Australia ‘2001 (in press). |
| Project Title | Postgraduate scholarship – Ron Newman: Manipulation of lean tissue deposition in broiler chickens by altering the sensitivity of tissues to insulin |
| RIRDC Project No: | US-68A |
| Researcher: | Mr Ron Newman and A/Prof Wayne L Bryden |
| Organisation: | University
of Sydney
Department of Animal Science Werombi Road CAMDEN NSW 2570 |
| Phone: | (02) 4655 0658 |
| Fax: | (02) 4655 0693 |
| Email: | wayneb@camden.usyd.edu.au |
bjective |
·
To investigate strategies, based on altering the fatty acid composition
of the diet, for reducing fat deposition and increasing lean meat deposition
in broilers.
|
ackground |
The selection for rapid growth of the modern broiler strains has been accompanied by increased fat deposition. Glucose-insulin balance has been suggested as the main reason for the increased adiposity in broilers. It has been shown that dietary fatty acid profile can alter adiposity in mammals by changing tissue insulin sensitivity and this was studied in birds in the project. |
Research |
Studies were designed to examine the effects of n-3 (fish oil) and n-6 (sunflower oil) polyunsaturated fatty acids in comparison to a saturated fat (tallow) on physiological and morphological characteristics of broilers. |
Outcomes |
Research undertaken showed that broilers fed either of the polyunsaturated fats (fish or sunflower oils) had a significant reduction in fat pad mass and an increase in breast muscle weight compared to broilers fed tallow. The changes in body composition were without penalty on weight gain and feed conversion efficiency. The n-3 and n-6 fats achieved reduced lipid deposition through different mechanisms. |
Implications |
The project has shown that simple dietary manipulation can alter carcass composition and potentially have a positive impact on the economics of broiler production, especially the further processing trade. Further studies are required to determine the optimal fatty acid or combination of fatty acids that reduce lipid deposition. |
Publications |
Newman,
R.E., Downing, J.A., Dehon, J.A. and Bryden, W.L. (1998) Manipulation
of glucose metabolism in the broiler chicken with dietary fatty acids.
Proc.
Aust. Poult. Sci. Symp. 10: 210.
Newman, R.E., Downing, J.A., Bryden, W.L., Fleck, E., Buttemer, W.A. and Storlien, L.H. (1998) Dietary polyunsaturated fatty acids of the n-3 and the n-6 series reduce abdominal fat in the chicken (Gallus domesticus). Proc. Nutr. Soc. Aust. 22: 54. |
|
|
Newman,
R.E., Downing, J.A., Jackson, C.M. and Bryden, W.L. (1999) Differences
in glucose metabolism between broiler and layer chickens. Proc. Aust.
Poult. Sci. Symp. 11: 164.
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