Chicken Meat - Completed Projects

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RIRDC Completed Projects in 1998-1999 & Research in Progress as at June 1999
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SUB-PROGRAM 3.1 - CHICKEN MEAT

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COMPLETED PROJECTS
PROJECT No	PROJECT TITLE	RESEARCHER	PHONE	ORGANISATION
DAN-158A	Infectious proventriculitis and stunting syndrome of broiler chickens	Dr R Reece	02 4640 6327	NSW Agriculture
DAV-120A	The effect of Salmonella Sofia on intestinal infection with other salmonellae in chickens	Dr C Wilks and Ms P Young	03 9217 4200	Department of Natural Resources and Environment, Victoria
CSJ-2A	Control of ovarian development and function in meat chicken females	Dr J Downing	02 4655 0600	University of Sydney
SGH-5A	Managing Structural Change in the Australian Poultry Industry	S G Heilbron and J T Larkin	03 9249 9542	S G Heilbron Pty Ltd
UM-43A	Scoping studies on infectious causes of immunodepression and transmissible viral proventriculitis in Australian broiler flocks	Dr T Bagust	03 9344 9676	University of Merlbourne
UMO-12CM	Identification of in vivo expressed antigens of Pasteurella multocida	Prof Ben Adler	03 9905 4815	Monash University
UNE-54A	Increasing efficiency of len tissue deposition in broiler chickens	Dr M Choct	02 6773 5121	University of New England
UNS-11A	Odour and ammonia emission from broiler chicken growout farms		02 9385 5452	University of New South Wales
US-34A	Development of DNA vaccines and techniques for cytokine manipulation for improved mucosal immunity in chickens	Prof A Husband and Dr W Muir	02 93517130	University of Sydney
US-38A	Broiler feed formulation based on digestible amino acids	A/Prof W Bryden and Dr R Ravindran	02 46 550 658	University of Sydney
UTS-2A	A maternally-delivered vaccine against coccidiosis in broiler chickens	Dr N Smith	02 9514 4013	University of Technology, Sydney
YCH-1A	Chicken Meat usage and attitude survey	Mr D Ellem, Mr M Steele, Mr Tam Tran	02 9927 0007	Yann Campbell Hoare Wheeler

Completed Projects

Project Title	Infectious proventriculitis and stunting syndrome of broiler chickens
RIRDC Project No.:	DAN-158A
Researcher:	Dr Rod Reece
Organisation:	NSW Agriculture Elizabeth Macarthur Agricultural Institute PMB 8 CAMDEN NSW 2570
Phone:	02 4640 6327
Fax:	02 4640 6400
Email:	rod.reece@agric.nsw.gov.au
Objective	To control outbreaks of infectious proventriculitis and stunting syndrome associated with reduced growth and poor performance of broiler chickens by understanding the pathogenesis, determining the aetiology, developing diagnostic tests and producing an appropriate vaccine.
Background:	Infectious stunting syndromes have been an intermittent and sometimes serious problem in the Australian broiler chicken industry from the early 1980s. In the summer of 1993/94, and thereafter, the form of this infectious stunting syndrome involving proventriculitis occurred in several companies in NSW, Victoria and SA. In affected flocks corrected feed conversion was poor, flocks were uneven, weight for age was reduced and litter deteriorated. Major problems were also encountered due to downgrading at abattoirs and difficulties were experienced in fulfilling market contracts and in forward planning of chick placements onto farms where chickens had to be kept for longer than anticipated in order to attain marketable weights. The clinical and pathological findings in the affected birds were similar to those described overseas for transmissible proventriculitis, the aetiology of which has not been defined. Thus, this disease was of considerable concern to the broiler chicken industry and warranted further studies aimed at providing control strategies based on the results of investigations into the aetiology and pathogenesis of the syndrome.
Research	During 1997-1998, broiler chickens from 56 flocks affected with typical infectious proventriculitis and stunting syndrome were examined. The syndrome was described and differentiated from other diseases with which it could be confused, and samples were collected for histological study, future transmission studies involving experimental chickens, electron-microscopy and possible isolation and/or characterisation of the aetiological agent(s). Three transmission trails were undertaken using intestinal and proventricular homogenates from affected birds as inoculae. In one trial, 100% of chickens showed typical gross and histological lesions at four weeks post-inoculation.
Outcomes	The infectious proventriculitis stunting syndrome was defined in pathological terms and confirmed as being associated with significant production problems in seven companies and in five states. Experimental studies demonstrated that the disease was transmissible and therefore due to some infectious agent, but the putative aetiological agent was not identified, let alone characterised.
Implications	The infectious proventriculitis stunting syndrome seen in Australian broiler flocks is transmissible and therefore due to an infectious agent. Further studies are now underway to identify the causative agent, so that appropriate diagnostic and control strategies for the disease can be developed.

Project Title	*The effect of Salmonella* Sofia on intestinal infection with other salmonellae in chickens**
RIRDC Project No.:	DAV-120A
Researcher:	Dr Colin Wilks and Ms Petrina Young
Organisation:	Dept of Natural Resources and Environment Victorian Institute of Animal Science 475 Mickleham Road ATTWOOD VIC 3049
Phone:	03 9217 4200
Fax:	03 9217 4299
Email:	Petrina.Young@nre.vic.gov.au
Objective	To determine whether or not prior intestinal infection with Salmonella Sofia limits the colonising ability, on subsequent exposure, of other salmonellae that are pathogenic to humans.
Background:	Infection of commercial broiler chickens in Australia with S Sofia is relatively common. This serovar of salmonella does not appear to be associated with significant disease in chickens nor has it been identified as a major cause of disease in humans. It is possible that an established intestinal infection with S. Sofia limits the ability of other pathogenic species of salmonella to subsequently infect and colonise the intestine. Such an effect may be due to a process described as ‘competitive exclusion’. If S. Sofia is shown to be an effective competitive excluder then there are considerable advantages in exploring ways to use this property to control infection with other salmonella serovars of more health concern without the need to resort to antibiotic or vaccine usage.
Research	In the first stage of the research, strains of Salmonella Sofia and Typhimurium (a pathogenic species) were selected. They were made resistant to specified antibiotics to enable their direct culture and enumeration in the faeces of chickens that had been infected with them. In the second stage, a protocol was developed which reliably established a persistent infection in chickens with S. Sofia in chickens at one day of age and with S. Typhimurium at five days of age. In the third stage, a series of experiments were run in which chickens which had been infected with Sofia at one day of age were then challenged with Typhimurium at five days of age. This enabled a comparison to be made on the ability of Typhimurium to infect chickens that had or had not been infected previously with Sofia.
Outcomes	The appropriate strains were selected and rendered resistant to the required antibiotics. Optimal doses were determined for establishing the infections by oral dosing at one day of age for Sofia and at five days of age for Typhimurium. Work undertaken also demonstrated that chickens could be readily infected by spraying eggs at the point of pipping with a suspension of Sofia. When the effect of prior infection with Sofia on subsequent infection with Typhimurium was tested it was found that no protective effect could be demonstrated. About this time we became aware through the work of a colleague in South Australia that not all strains of Sofia were the same. With his assistance a collection of strains of Sofia was put together and the protective effect of each of these was tested in the model that had been developed. Almost all of the strains provided no detectable protection but one strain, Number 76, persisted for much longer in the infected chickens and clearly inhibited the ability of Typhimurium to become established.
Implications	It appears that with selection of a suitable strain of Sofia, inhibition of infection and persistence of Typhimurium can be affected. This experiment needs to be repeated to confirm the results but there is good reason to be optimistic that under suitable conditions and with suitable strains, that competitive exclusion could provide an alternative to other methods of minimising salmonella infection in chickens.

Project Title	Control of ovarian development and function in meat chicken females
RIRDC Project No.:	CSJ-2A
Researcher:	Dr Jeff Downing
Organisation:	University of Sydney Department of Animal Science 425 Werombi Road CAMDEN NSW 2570
Phone:	02 4655 0600
Fax:	02 4655 0693
Email:	jeffd@camden.usyd.edu.au
Objective	To determine whether hexadimethrine (HDM) and/or protamine sulphate could be safely used to manipulate follicle development in hen
Background:	Broiler breeder hens do not produce as many eggs as laying hens. Earlier studies have suggested that this is because too many follicles develop in the ovary of these hens.
Research	The ability of two compounds to inhibit the stimulatory effect of fibroblast growth factor on ovarian follicle development was investigated. Studies on the safety of these compounds for hens were also undertaken.
Outcomes	One compound investigated was found to enter cells of the ovarian follicle. This demonstrated that the compound could be administered and reach the target cells. Large amounts of this compound were, however, extremely toxic for hens, but small doses appear to have no deleterious effects on hen health. Administration of the compound, at certain delivery rates, had effects on follicle numbers and/or on the egg production of layer hens.
Implications	A compound was identified which was capable of affecting follicular development in the hen. Whether it (or some related compound) can be used to manipulate egg production in broiler breeder hens has yet to be proven.

Project Title	Managing structural change in the Australian poultry industry
RIRDC Project No.:	SGH-5A
Researcher:	Mr Selwyn Heilbron and Mr Terry Larkin
Organisation:	S G Heilbron Pty Ltd 832 High Street, EAST KEW VIC 3102
Phone:	03 9249 9542
Fax:	03 9249 9600
Email:	heilbron@eisa.net.au
Objective	To assist the industry in evaluating its performance and readiness for change and to develop a blueprint for future growth
Background:	The Australian chicken meat industry has an impressive record of growth but it is now facing a new era of challenge and opportunity arising from deregulation, microeconomic reform, international trade challenges and structural change. The industry needs to assess its readiness for change and chart out a blueprint for future growth.
Research	The research applies techniques of business change management supplemented by economic and agribusiness analysis to evaluate performance and to develop a strategy for future development.
Outcomes	Improved competitiveness can substantially improve future growth. The international benchmark – the United States industry – however appears to be driving further ahead. The Australian industry is exhibiting evidence of successful change but more needs to be done. Value chain problems outside the industry’s control, particularly ACCC obstacles, feed costs and labour "on-costs" require policy attention by governments.
Implications	The industry should accelerate its positive attitudes to change and press on with further analysis of international benchmarks and domestic value chain improvement.

Project Title	Scoping studies on infectious causes of immunodepression and transmissible viral proventriculitis in Australian broiler flocks
RIRDC Project No.:	UM-43A
Researcher:	Dr Trevor J Bagust
Organisation:	University of Melbourne Faculty of Veterinary Science Post Office PARKVILLE VIC 3052
Phone:	03 9344 9676
Fax:	03 9344 9675
Email:	t.bagust@vet.unimelb.edu.au
Internet:
Objectives	To define the dynamics of the viral infections which are challenging broiler flocks during their production cycle, and relating findings to production performance. To undertake scoping laboratory investigations to enable a clearer focus on the most likely cause(s) of transmissible viral proventriculitis disease.
Background:	In recent years, some Australian broiler flocks have been exhibiting lower growth rates and higher feed conversion ratios than are acceptable by industry standards. The deleterious effects of pathogenic (disease-causing) viruses, either by known or yet-to-be recognised viral agents, has been suspected by industry veterinarians.
Research	Flocks at four broiler production sites across NSW and Quuensland were studied by serological surveillance for evidence of infection by pathogenic viruses. Flocks were tested at two, four and six weeks of age and at kill-out. Findings for each flock were then compared with clinical histories, growth rates and mortalities. In addition, some 2000 serum samples from broiler breeders submitted from commercial companies were tested for evidence of avian leukosis subgroup J (ALV-J) infection. Transmissible viral proventriculitis (TVP) field occurrences that had been positively diagnosed at four field locations were examined virologically and serologically, in collaboration with the Elizabeth MacArthur Animal Institute of NSW Agriculture.
Outcomes	The immunodepressive pathogens, infectious bursal disease virus (IBDV) and chicken anaemia virus (CAV), were detected as challenges to young flocks on all sites. However the levels of maternal protection via antibody derived from parent breeders varied considerably between the sites, and in some cases was probably not sufficient to adequately protect one to three week-old chickens. Infectious bronchitis virus spread was also detected in problem flocks. ALV-J infection appears widespread in broiler parent stocks. TPV disease problems appeared to be most strongly associated with co-infection by an avian entero-like virus which was isolated in these studies and avian Group 1adenovirus. A contributing role for immunodepressive agents may also be occurring in these field cases.
Implications	Industry might need to reappraise control programs for immunodepressive pathogens such as IBDV. Laboratory technology for culture and rapid PCR diagnosis of ALV-J needs to be developed. Further detailed laboratory studies of TPV should be undertaken to determine the roles in the disease of the viruses identified above. TPV is a multifactorial disease syndrome.

Project Title	*Identification of in vivo* expressed antigens of Pasteurella multocida.**
RIRDC Project No.:	UMO-12CM
Researcher:	Prof Ben Adler
Organisation:	Monash University Department of Microbiology CLAYTON, VIC 3168
Phone:	03 9905 4815
Fax:	03 9905 4811
Email:	ben.adler@med.monash.edu.au
Objectives	To apply genetic techniques to identify potential vaccine antigens of P. multocida with emphasis on antigens which are expressed only when the bacteria are growing within the host (i.e. in vivo expressed antigens). To produce each antigen in purified recombinant form and test its ability to protect chickens from fowl cholera infection. To identify P. multocida genes which are involved in pathogenesis (the ability of the bacteria to cause disease) with emphasis on those expressed in vivo. To construct mutant P. multocida strains for each such gene and assess their virulence and ability to stimulate protective immunity.
Background:	Infection by Pasteurella multocida causes fowl cholera in poultry, bovine haemorrhagic septicaemia and porcine atrophic rhinitis. It is thus of major economic importance worldwide, but especially in Australia and South East Asia. Despite this, very little is known about its pathogenesis (disease causing ability) or about immunity to infection. This project seeks to apply modern techniques of molecular microbiology to identify bacterial antigens involved in immunity to infection (especially cross immunity among different serotypes) and to identify bacterial virulence genes which might be potential targets for attenuating mutations and thus provide the basis for the construction of live, attenuated vaccines.
Research and Outcomes	A genetic system was developed which allowed the identification of genes which encode antigens or other proteins of P. multocida which are expressed in vivo. A second approach targeted other candidate genes and antigens on the basis of their similarity to those of other bacterial species. This allowed the identification of a panel of potential vaccine antigens which were expressed and purified in recombinant form. At the time of writing three of these are undergoing chicken testing and at least another four are in various stages of cloning, expression or preparation. The construction of genetically defined mutant strains has been delayed by technical difficulties. However, one mutant strain was constructed and a further four putative virulence genes have been identified, cloned and sequenced and the genes disrupted in E. coli. The corresponding P. multocida mutants are currently under construction.
Publications	Eleven scientific papers on P. multocida were published in the project period and ten conference papers were presented. In addition, the work supported here was presented at invited seminars in Australia, Austria, Denmark, France, The Netherlands, Singapore and the USA. Please contact the researcher for details.

Project Title	Increasing efficiency of lean tissue deposition in broiler chickens
RIRDC Project No.:	UNE-54A
Researcher:	Dr Mingan Choct
Organisation:	University of New England ARMIDALE NSW 23510
Phone:	02 6773 5121
Fax:	02 6773 3275
Email:	mchoct@metz.une.edu.au
Objective	To increase the efficiency of lean meat growth in broiler chickens through nutritional manipulation of protein degradation via the insulin axis.
Background:	Genetic selection of broiler chickens over the past 40 years has resulted in extremely rapid growth rate. It has also increased carcass fat content. A combination of organic chromium and a branched-chain amino acid, leucine, and some long chain fatty acids may enhance protein deposition, thereby reducing fatness in broiler chickens.
Research	Two experiments were conducted to examine the effect of graded levels of organic chromium and leucine and four different fat sources on the body composition of broiler chickens.
Outcomes	Chromium picolinate at 0.5ppm significantly (P<0.05) lowered the carcass fat level. Leucine did not interact with chromium to effect lean growth. Chromium had no effect on bird performance. Dietary leucine above the recommended maintenance level (1.2% of the diet) markedly (P<0.001) reduced the breast muscle yield. The addition of fish oil to broiler diets reduced (P<0.05) the abdominal fat pad weights compared to birds on linseed diets. The amount of fat in the diet (2% or 4%) did not affect body composition.
Implications	Provisions could be made for chromium levels and some polyunsaturated fatty acids in practical feed formulations to take advantage of their effects on energy utilisation and carcass fat content.
Publications	Honours thesis entitled "Nutritional Manipulation of Lean Tissue Deposition in Broiler Chickens" by Adam Naylor, University of New England, Armidale.

Project Title	Odour and ammonia emission from broiler chicken growout farms
RIRDC Project No.:	UNS-11A
Researcher:	Mr John Jiang
Organisation:	University of New South Wales Odour Research Laboratory Centre for Water and Waste Technology PO Box 1 SYDNEY NSW 2052
Phone:	02 9385 5452
Fax:	02 9313 8624
Email:	johnj@unsw.edu.au
Internet:	http://www.odour.civeng.unsw.edu.au
Objective	To quantify odour and ammonia emissions in and adjacent to a selection of typical broiler farms and to identify and make recommendations on potential remedial measures with a particular focus on operational and management aspects.
Background:	n recent years, local councils have received increasing numbers of odour complaints from residents living in the vicinity of broiler growout farms. Growers have experienced difficulty in obtaining approval to expand existing farms and to establish new farms. Project outcomes should provide a more scientifically informed basis for establishing planning guidelines and the setting of regulatory requirements.
Research	Detailed studies were undertaken on two typical New South Wales broiler farms over four seasons and spot surveys undertaken at a further ten broiler farms in New South Wales and Victoria. The study included measurement of ammonia concentration, odour concentration and ventilation rates in broiler sheds, the investigation of odour intensity relationships for broiler farm odour, the application of Ausplume dispersion modelling to seven of the farms and the conduct of a community survey in the vicinity of one of the farms.
Outcomes	The primary outcomes of the project have been the development of a database of information on odour emission rates, odour intensities and ammonia emissions associated with broiler farms, the development of an improved understanding of odour generation within and dispersion from broiler farms and the development of a set of recommended strategies to assist in the reduction of odour impacts during the chicken growout phase of chicken meat production. Odour dispersion modelling undertaken on the odour emission data collected in the course of the project has established preliminary odour impact criteria for Australian broiler farms.
Implications	Baseline data on odour concentrations within and odour emissions from broiler farms generated by this research is now available for use by industry in assessing, in a quantitative way, its (odour) impacts on the environment and for use in planning applications. The project has paved the way for the development of an accepted protocol for assessing broiler farm odour impacts upon which planning guidelines may in the future be based.
Pulbications	Jiang, J. K. and Sands, J. R., (1997) Odour and ammonia emission at Australian broiler and growout farms. Proc. Int. Symp. Ammonia and Odour Emissions from Animal Production Facilities. pp 239 -244

Project Title	Development of DNA vaccines and techniques for cytokine manipulation for improved mucosal immunity in chickens
RIRDC Project No.:	US-34A
Researcher:	Prof Alan Husband and Dr Wendy Muir
Organisation:	University of Sydney Department of Veterinary Anatomy and Pathology SYDNEY NSW 2006
Phone:	02 93517130
Fax:	02 93517348
Email:	w.muir@vetp.usyd.edu.au
Objective	To improve understanding of the operation of the gut immune system in chickens by (i) determining the ability of in ovo delivery of antigen and/or immunoregulatory substances to increase IgA antibody at the gut; and (ii) identifying soluble messengers of the immune system (cytokines) involved in controlling levels of IgA production at the gut.
Background:	IgA antibody acts as the first line of defence at the intestinal lumen, which is the site through which a number of pathogens first colonise the chicken. Therefore, increased IgA antibody titres at this site should assist in reducing pathogen infection of the gut. IgA antibody may be increased by immunisation, and in particular by delivery of antigen and adjuvant to the intestinal area. Secondly, extensive studies in mice have shown that particular cytokines very closely control features of the immune response. Further, delivery of the appropriate cytokines as a part of an immunisation strategy can increase IgA antibody titres. Therefore, these studies were designed to identify those avian cytokines which regulate IgA antibody in chicks.
Research	In ovo delivery of antigen with and without immunoenhancer to the 18 day embryo increased total IgA antibody in the first two weeks of life, compared to unimmunsed chickens. However, detailed assessment of the interactions between antigen/immunoenhancer combinations are required as not all substances will increase IgA antibody titres when delivered under this regimen. The cytokine, transforming growth factor-b (TGF-b ), is intrinsically involved in regulating IgA antibody production in chickens following vaccination, being present at high levels during the first two days after delivery of an oral booster antigen to previously immunised chickens. A second cytokine, chicken myelomonocytic growth factor, may also regulate IgA antibody in chicks, however it is observed less frequently than TGF-b .
Outcomes	In ovo immunisation of antigen with or without immunoenhancer increases the presence of IgA antibody in chicks during the first two weeks of life. This effect is enhanced when chicks receive an oral booster immunisation of antigen at seven days of age. The cytokine TGF-b acts to direct the immune response in favour of IgA antibody production.
Implications	The levels of IgA antibody in young chicks is improved by the delivery of antigen/immunoenhancer to the 18 day embryo. The generation of IgA antibody at the intestinal site is controlled by the cytokine TGF-b . Ongoing research will evaluate the feasibility of delivering combinations of antigen/immunoenhancer and TGF-b to the embryo, using Embrex Inoveject, to improve levels of IgA antibody posthatch, thereby reducing morbidity and mortality due to enteric pathogens early in life. If successful, this in ovo immunisation strategy could be readily adopted by the industry where in ovo immunisation is already employed.

Project Title	Broiler feed formulation based on digestible amino acids
RIRDC Project No.:	US-38A
Researcher:	A/Prof Wayne Bryden and Dr Ravi. Ravindran
Organisation:	University of Sydney Dept of Animal Science CAMDEN NSW 2570
Phone:	02 4655 0658
Fax:	02 4655 0693
Email:	wayneb@camden.usyd.edu.au
Objectives	To evaluate the formulation of broiler diets on a total amino acid basis vs digestible amino acid basis, with particular reference to inclusion of cheaper, alternative feed ingredients. To examine the utility of the digestible amino acid concept in low-protein diets for broilers.
Background:	There is little doubt that the poultry feed industry requires a better feed formulation system than the one based on total amino acids. With the accumulation of amino acid digestibility data, there is also growing interest in how to use these values in feed formulations. Amino acid digestibility is not the same in all feed ingredients. Some ingredients have lower digestibilities than others. These differences in digestibility can be effectively used as a tool to improve the precision of feed formulations.
Research	A series of growth assays were conducted to demonstrate that differences in digestible amino acid content of feed ingredients result in comparable differences in broiler performance
Outcomes	Formulating diets using digestible amino acid values for meat and bone meal, canola meal and cottonseed meal resulted in superior bird performance than formulation on a total amino acid basis
Implications	Feed formulations based on digestible amino acids will allow the industry to increase the inclusion levels of cheaper, alternative protein sources, to improve the precision of least cost diet formulation and to reduce feed costs. Nitrogen excretion by birds will also be decreased.
Publications	Ravindran, V., Hew, L.I. and Bryden, W.L. (1998) Influence of guanidination on apparent ileal amino acid digestibility in some protein sources for broilers. Poult. Sci. 77:873-877. Ravindran, V., Hew, L.I. and Bryden, W.L. (1998) Broiler feed formulations with canola meal based on total or digestible amino acids. Proc. Aust. Poult. Sci. Symp. 10:209. Bryden, W.L. and Ravindran, V. (1999) Enzyme combinations and nutrient digestibility of wheat for broiler chickens. Proc. Aust. Poult. Sci. Symp. 11:170. Bryden, W.L., Hew, L.I., Ravindran, V. and Ravindran, G. (1999) Ileal amino acid digestibility for broilers of wheat grown in Australia. Proc. Aust. Poult. Sci. Symp. 11:162. Ravindran, V. and Bryden, W.L. (1999) Evaluation of broiler diets containing graded levels of cottonseed meal and formulated on the basis of total or digestible amino acids. Proc. Aust. Poult. Sci. Symp. 11:168. Ravindran, V. and Bryden, W.L. (1999) Evaluation of meat and bone meal in broiler starter diets formulated on the basis of total or digestible amino acids. Proc. Aust. Poult. Sci. Symp. 11:169. Ravindran, V. and Bryden, W.L. (1999) Amino acid availability in poultry: in vitro and in vivo measurements. Aust. J. Agric. Res. In press.

Project Title	A maternally-delivered vaccine against coccidiosis in broiler chickens
RIRDC Project No.:	UTS-2A
Researcher:	Dr Nicholas Smith
Organisation:	Molecular Parasitology Unit Department of Cell and Molecular Biology University of Technology, Sydney Westbourne Street, GORE HILL, NSW, 2065
Phone:	02 9514 4013
Fax:	02 9514 4026
Email:	Nick.Smith@uts.edu.au
Objectives	To prove the feasibility of utilising maternal immunity in the control of coccidiosis by determining whether it is possible to induce the production of maternal antibodies to protect hatchlings against infection with many species of Eimeria by immunisation of breeding hens with a single species of Eimeria specifically. To confirm that immunisation of hens by oral infection with 10,000 oocysts of Eimeria maxima results in maternal immunity to E. maxima, E. tenella and E. acervulina; To determine which stage of infection is affected by maternal antibodies induced by oral infection of hens with E. maxima. To confirm that immunisation of hens by injection of E. maxima gametocyte antigens results in maternal immunity to E. maxima, E. tenella and E. acervulina.
Background:	Coccidiosis is one of the most economically significant diseases of the commercial poultry industry. It is caused by protozoan parasites named Eimeria. Since 1990, considerable research has been devoted to assessing the feasibility of protecting broiler chickens against coccidiosis by vaccinating their parent hens with proteins derived from the parasite; the vaccinated hens produce large quantities of antibodies which are transferred into the egg yolk and are consequently absorbed by the hatchlings. These antibodies inhibit infection. One of the major impediments to the successful application of a subunit vaccine to control coccidiosis is the fact that several different species of Eimeria infect chickens and cause disease. There is, however, evidence that maternal immunisation with selected proteins from the parasite overcomes this obstacle. A subunit vaccine delivered maternally is anticipated to be a very effective and economical way to control coccidiosis in broiler chicken flocks.
Research	Hens were immunised with purified gametocyte proteins of E. maxima or by inoculation with virulent oocysts. The production and transfer of antibodies against Eimeria was monitored in hatchlings. Maternal immunity in hatchlings was determined by infecting hatchlings with various species of Eimeria and measuring how many parasites were able to reproduce in the chickens.
Outcomes	The experiments confirmed that immunisation of hens, either by infection or by injection of parasite proteins, resulted in maternal immunity to E. maxima and E. acervulina. The experiments did not confirm previous observations that this control strategy also induced maternal immunity to E. tenella. The antibody response of the Australian Ross 308 breeder used in these experiments was relatively weak compared to that seen in other breeds of chickens in previous trials and only protected hatchlings against weak or moderate infections, not against very virulent infections; this probably explains why no resistance to the very virulent Australian strain of E. tenella was seen.
Implications	This research has demonstrated that it should be feasible to use maternal immunity as part of a control strategy for coccidiosis in broiler chickens. This principle is being further developed by commercial interests.

Project Title	Chicken meat usage & attitude survey
RIRDC Project No.:	YCH-1A
Researcher:	David Ellem, Matthew Steele, Tam Tran
Organisation:	Yann Campbell Hoare Wheeler 357 Military Road, MOSMAN NSW 2088
Phone:	02 9927 0007
Fax:	02 9953 9035
Email:	david.ellem@au.millwardbrown.com
Objectives	To identify consumer perceptions which promote chicken consumption. To identify consumer perceptions that act as barriers to increased chicken consumption. To determine the relative importance of these perceptions. To establish baseline data for future research.
Background:	Although chicken meat consumption continues to grow, the industry is interested in identifying those consumer perceptions that may act as barriers to the growth in chicken consumption and those consumer perceptions which are promoting growth in chicken consumption so that strategies can be devised to further develop the market for chicken meat.
Research	The Chicken Meat Usage & Attitude study consisted of two separate stages. Stage 1 was a population incidence survey based on 1200 telephone interviews conducted nationally among adults 18 years and over between 27-29th November 1998. Stage 2 was a quantitative study based on 849 telephone interviews conducted in Sydney and Melbourne among main grocery buyers aged 18 years and over. This survey was carried out between 11th December 1998 - 11th January 1999. Data was post-weighted to reflect population incidence figures obtained in Stage 1.
Outcomes	The key perceptions of chicken are overwhelmingly positive. It is seen as an automatic choice for purchase because its popularity with the household, its value for money and its versatility mean it is a food that can be eaten often. Interestingly, the least important perceptions were those related to farming practices, sometimes raised in the media and often inaccurately reported or unfounded, that could give rise to concerns about the safety or health value of chicken meat. About one in four grocery buyers claim to eat "more" chicken compared to twelve months ago; about one in five grocery buyers claim to eat "less" chicken. The most common reasons given for eating "less" chicken than twelve months ago were "change in family numbers/lifestyle" and "change in personal taste"; whilst the most common reasons given for eating "more" chicken than twelve months ago were "health reasons" and "like the taste". The main reasons given for lack of appeal among grocery buyers who found chicken unappealing are "dislike taste" and "vegetarian".
Implications	It is recommended that the industry utilise a ‘public relations’ approach towards promoting and sustaining the current strong positive image which grocery buyers have of chicken as a food for main meals. The ‘public relations’ approach is more relevant than an ‘advertising campaign’ approach because the key sources of information used by grocery buyers to obtain information about food, as identified by the study, are newspaper articles, magazine articles and TV news programs.

Last updated: 6 September 1999
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