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RIRDC Completed Projects in 1999-2000 & Research in Progress as at June 2000
| Project Title | Broiler feed formulation based on digestible amino acids |
| RIRDC Project No: | US-38A |
| Researcher: | A/Prof Wayne 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 |
| Objectives |
· To evaluate the formulation of broiler diets on a total amino acid basis vs digestible amino acid basis, with particular reference to the inclusion of cheaper, alternative feed ingredients. |
| 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 of diets 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. |
| Project Title | Manipulation of lean tissue deposition in broiler chickens by altering the sensitivity of tissues to insulin |
| RIRDC Project No: | US-44A |
| Researcher: | A/Prof Wayne 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 |
| Objective |
· To reduce fat deposition in broiler chickens by modulation of tissue insulin sensitivity as a result of changes in dietary fatty acid composition. |
| Background | 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 | Broilers fed either polyunsaturated fat (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. |
| Project Title | Total and digestible tryptophan content of feedstuffs for poultry |
| RIRDC Project No: | US-51J |
| Researcher: | A/Prof Wayne Bryden |
| Organisation: | University of Sydney
Werombi Road CAMDEN NSW 2570 |
| Phone: | (02) 4655 0658 |
| Fax: | (02) 4655 0693 |
| Email: | wayneb@camden.usyd,edu.au |
| Objective |
· To develop a database of total and digestible tryptophan contents of feedstuffs for poultry which can be used by the feed industry to formulate more efficient diets. |
| Background | Tryptophan is an essential amino acid for poultry and may become limiting, especially when diets are based on sorghum, lupins, peas and meat and bone meal. Reliable values of total and digestible tryptophan in feedstuffs for use in feed formulation matrixes are therefore needed. Values for tryptophan are seldom reported in amino acid profiles of feedstuffs. This is because tryptophan is oxidatively destroyed during acid hydrolysis in routine amino acid analysis and its determination requires a separate analytical procedure. A procedure involving alkaline hydrolysis with sodium hydroxide followed by separation of tryptophan by ion exchange chromatography has recently been developed and validated for the routine analysis of tryptophan in feeds. |
| Research | The tryptophan content of 93 samples of 25 Australian feedstuffs including cereals, cereal by-products, oilseed meals, grain legumes, animal protein meals and miscellaneous products was determined. For 81 of the samples apparent ileal digestibility coefficients for tryptophan were also determined |
| Outcomes | The tryptophan content and apparent ileal digestibility coefficients for tryptophan determined for a large sample of Australian feedstuffs in the course of this project, have added to and significantly enhanced the database of information on the ileal amino acid digestibility of Australian feedstuffs generated in a previous project. It was also shown that apparent ileal digestibility of tryptophan is similar for broilers and layers. |
| Implications | The Australian poultry industry now has a comprehensive data set of the amino acid content and apparent ileal digestibility of amino acids for the range of ingredients used in Australian poultry diets. This will enable the industry to develop more efficient feed formulations and improve the strategic use of commercially available, synthetic, feed-grade amino acids, including tryptophan. |
| Publications |
Ravindran, G. and Bryden, W.L. (1997) Tryptophan content of sorghum grain varying in nitrogen content. Proc.. Aust. Poult. Sci. Symp. 9:229. |
| Project Title | Nutritional value of pearl millet as poultry feed |
| RIRDC Project No: | DAQ-243J |
| Researcher: | Mr Danny Singh and Dr Rider Perez-Maldonado |
| Organisation: | Department of Primary Industries
(Qld)
Animal Research Institute Locked Mail Bag No 4 MOOROOKA QLD 4105 |
| Phone: | (07) 3362 9479 |
| Fax: | (07) 3362 9429 |
| Email: | singhd@dpi.qld.gov.au |
| Objectives |
· To determine the gross chemical composition, metabolisable energy content and digestible amino acid values of varieties of millet when fed to broilers and layers. |
| Background | With the escalation of poultry feed prices and the real prospect of declining availability of grains for livestock, it is opportune that research efforts be directed towards finding alternatives to wheat/sorghum based diets. Pearl millet has been identified as a suitable alternative crop to sorghum in low rainfall and sandy areas in Queensland. The potential benefits from the application of existing knowledge and new information from further research on pearl millet are substantial for feed grain crops in warm-temperate agriculture. In the US, pearl millet is considered to be the new feed grain crop in a number of States. The feeding value of pearl millet varieties available in Australia has never been determined in the past. |
| Research | Katherine pearl millet and Siberian millet were grown at Biloela Research Station, Biloela, Queensland and clean grain was transported to the Queensland Poultry Research and Development Centre for evaluation. Chemical analyses were performed on these two grains to measure the protein, fat, fibre, starch, phosphorus, calcium, gross energy and amino acid content. Feeding experiments were conducted in broiler and layer birds to measure the metabolisable energy content and the digestibility of amino acids in the two millets. Finally, an inclusion level experiment was conducted to determine the upper level of inclusion of the millets in the diets of layer birds for satisfactory performance. |
| Outcomes | Both millet varieties had higher protein, fat, starch and crude fibre levels than did sorghum. The total amino acid profile of Katherine pearl millet is much better than sorghum and Siberian millet. The apparent metabolisable energy (AME) content of Katherine pearl millet was more than 1 mega joule (MJ) higher than Siberian millet and sorghum. The amino acid digestibilities of Katherine pearl millet were 5-7% higher in broilers than in layers. The layer feeding experiment showed that diets containing inclusion levels of up to 600 g/kg of the Katherine millet and 400 g/kg of Siberian millet had no effect on egg production, feed conversion, egg weight, egg mass, specific gravity and bird final body weight. |
| Implications | The experiments conducted demonstrated the nutritive value of the millets for poultry diets, which is important when formulating least cost diets. The layer experiment showed that Katherine pearl millet could be incorporated in the diet without any adverse effect on layer performance. Since the millets contain high levels of fibre this could be a limiting factor, however the utilisation of fibre could be improved with the use of specific feed enzymes. As the ileal amino acid digestibilities of millets are different in broilers and layers, this differences implies that different sets of coefficients need to be used when formulating diets based on amino acid digestibilities. The results from ileal amino acid digestibility and from the AME studies suggests that the millets could be used as feed ingredients in broiler diets. |
| Publications |
Singh, D.N., Perez-Maldonado, R., Mannion, P.F. and Robinson, D. (2000) Pearl millet (Pennistum americanum) – an alternative feed grain for layers. Proc. Aust. Poult. Sci. Symp.12:133-136. |
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| Project Title | A welfare audit for the broiler industry |
| RIRDC Project No: | DAV-147A |
| Researcher: | A/Prof John Barnett |
| Organisation: | Department of Natural Resources
and Environment
Victorian Institute of Animal Science Animal Welfare Centre Private Bag 7, Sneydes Road, WERRIBEE VIC 3030 |
| Phone: | (03) 9742 0433 |
| Fax: | (03) 9742 0400 |
| Email: | john.barnett@nre.vic.gov.au |
| Objective |
· To develop practical audit documentation for industry to use either independently or to incorporate into quality assurance programs for use in welfare assessment for the breeding, hatchery, rearing and grower sectors of the broiler industry. |
| Background | This project on welfare audit
documentation was developed to help fulfil both industry’s and the community’s
expectations of high levels of quality assurance associated with chicken
meat production. It has been developed specifically focussing on conditions
in south east Australia, but would require only minor modifications for
use in other parts of Australia. Quality assurance programs within industry
currently focus predominantly on animal health and food safety and there
is a need, coinciding with a more informed and demanding customer base,
to expand these programs to include animal welfare issues so that industry
remains sustainable into the next century. Similarly, there will be a need
in the future to include environmental audits into quality assurance programs.
A large number of the issues that breeders focus on daily, including animal
health, production and food safety, also relate to animal welfare, although
this information was not previously formalised within one document. Broiler
companies already provide considerable information on maintaining high
levels of animal welfare and producers, in their daily tasks, already largely
implement this information.
Current work undertaken within a related project will complete the documentation for pick-up, transport and processing sectors of the broiler industry and thereby provide the first comprehensive welfare audit documentation for any animal industry. |
| Research | Four booklets have been provided and are currently being circulated to industry for feedback. They are independent documents for the breeding, hatchery, rearing and growing sectors of the chicken meat industry. |
| Outcomes | Practical audit documentation has been provided for industry to use, either independently or via their incorporation into quality assurance programs, for welfare assessment that reflects industry’s continuing commitment to high standards of animal welfare for the following sectors of the broiler industry (breeding, hatching, rearing and growing). |
| Implications | There are some short term and long term benefits of the project. The short term benefits are those to be gained from advertising industry’s proactive position on animal welfare with welfare groups, the public, the retail sector and relevant state and federal government bodies. The long term benefits will only be achieved by implementation of the audit process. These benefits will include an ability by industry to demonstrate compliance with codes of practice and welfare targets, improvements in compliance levels with targets over time, an ability to identify and solve problems on individual farms and, where necessary, to initiate industry education on specific issues and. By these actions, the industry will be able to reassure the public that appropriate welfare standards are being met within the chicken meat industry. |
| Publications |
Barnett, J., Glatz, P. and Almond, A. (1999) A welfare audit for the grower, hatchery and laying sectors of the chicken meat industry in South Eastern Australia. Proc. South Aust. Pig and Poult. Fair pp.44. |
| Project Title | The development of a model of abnormal bone development in broiler chickens as an aid in the assessment of welfare |
| RIRDC Project No: | US-35A |
| Researcher: | A/Prof Wayne 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 |
| Objective |
· To develop a model of tibial dyschrondroplasia (TD) using the mycotoxin fusarachomanone that will allow study of the dyschondroplasic lesion and examination of the factors reported to modulate the incidence of the disease. |
| Background | Leg weakness, an ongoing problem for the broiler industry, is the collective name of a number of different bone pathologies, of which TD is the most often described. Despite many years of study, and the delineation of many factors which influence the incidence of TD, the direct cause of TD remains unknown. Leg weakness has serious welfare implications and results in economic losses to the broiler industry. |
| Research | Rice fungal culture material contaminated with fusararchromanone, a mycotoxin, was used to induce TD in broiler chickens. In most experiments TD susceptible and tolerant broiler strains were examined, especially in relation to TD incidence and vitamin D metabolism. |
| Outcomes | The experimental model of TD using fusarachromanone was shown to consistently induce TD. However, genetic predisposition to the disease was a critical factor in the development of TD with one broiler strain being resistant to the effects of the toxin. It was also demonstrated in these studies that vitamin D is intimately involved in the aetiology of TD but the mechanism of the interaction remains to be elucidated. |
| Implications | There was no evidence in the present studies that TD is associated with overt leg weakness. The significance of TD as a practical problem for the Australian broiler industry may, therefore, need to be reassessed. Nevertheless, a greater understanding of TD will provide invaluable knowledge on bone development and associated leg weakness. |
| Publications |
Lowe, M., Bryden, W.L., Fraser, D.R. and Ravindran, V. (1997) Plasma 1,25 dihydroxy cholecalciferol levels in broiler chickens as influenced by dietary levels of phytic acid, available phosphorus and phytase. Proc. Nutr. Soc. Aust. 21:147. |
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| Project Title | Literature review of air quality within poultry production facilities |
| RIRDC Project No: | DAS-47A |
| Researcher: | Dr Colin Cargill |
| Organisation: | South Australian Research and
Development Institute
Pig and Poultry Production Institute GPO Box 397 ADELAIDE SA 5001 |
| Phone: | (08) 8303 7782 |
| Fax: | (08) 8303 7975 |
| Email: | cargill.colin@saugov.sa.gov.au |
| Objectives |
· To prepare a literature review of dust generation and dispersion from broiler sheds. |
| Background | Dust is one of the major airborne
pollutants associated with intensive livestock production and contributes
significantly to the quality of the environment within buildings housing
birds.
The role of dust in odour problems associated with livestock production facilities has been studied in Europe and North America but not to date in Australia. This review was undertaken in order to pull together the available international information on dust generation and dispersion from broiler sheds and its association with odour dispersion from sheds. |
| Research | A review was undertaken of available scientific and international industry literature in the area of airborne dust within poultry production facilities, with a particular emphasis on dust as a source of odour from such facilities. The areas covered in the review included the major sources of dust, mechanisms of dust generation and maintenance within poultry facilities, the dynamics of dust dispersion within sheds, the dispersion of dust ventilated from sheds, and the interaction between dust and odour. The review also considered strategies for reducing the generation of dust within sheds and for reducing odours associated with dust exhausted from sheds. |
| Outcomes | The amount of dust and airborne
particle matter present in a poultry house is dependant on several key
factors. These include bird activity, stocking density, cleaning activities
undertaken, bird handling, type of bedding or litter, ventilation system
used, season and building surrounds.
Ventilation rate is one of the main factors influencing dust emission rates from buildings and because many odourants are absorbed into dust particles, the odour emission rate is largely dependant on dust emissions. Hence odour levels in exhaust air can be reduced by 60 to 70% by removing dust. Odourants attached to dust also appear to produce a stronger and more lasting effect on human olfactory organs than when in gaseous phase. Average dust emission rates in UK broiler sheds range from approximately 5g/hour/500kg live weight of bird in winter up to 8g/h/500kg in summer for inspirable dust and from around 0.6g/h/500kg in winter up to 0.9g/h/500kg in summer for respirable dust. Emission rates in Australian sheds have not been studies but based on UK figures a poultry production enterprise of 100,000 birds on a single site, with a total weight at slaughter of approximately 200 tonne an demission rates of 8g/h/500kg body weight could potentially release a significant amount of odourant into the air via dust emissions. A range of strategies that could be considered for managing dust generation and dispersion from broiler sheds were suggested by the review. These included a range of bird, shed, litter and ventilation management strategies, techniques for filtering and cleaning air, the use of fogging or misting, ionisation and ozone treatment to reduce/settle dust and odour, and various dietary and feed manipulations. |
| Implications | The review highlighted the significant
role that dust has to play in the emission of odour from poultry production
facilities. Hence, strategies which have the effect of reducing dust in
poultry sheds or which reduce the amount of dust emitted from poultry sheds
will have an effect on odour emission.
A range of such strategies was suggested by this review and the industry should consider further evaluating these options as a means of reducing dust and odour emissions from broiler sheds. |
| Project Title | Odour emissions from broiler farm litter |
| RIRDC Project No: | UNS-15A |
| Researcher: | Mr John Jiang |
| Organisation: | The University of New South Wales
Centre for Water and Waste Technology SYDNEY NSW 2052 |
| Phone: | (02) 9385 5452 |
| Fax: | (02) 9313 8624 |
| Email: | j.jiang@unsw.edu.au |
| Internet: | http://www.odour.civeng.unsw.edu.au |
| Objectives |
· To investigate the extent to which anaerobic and/or aerobic processes may contribute to the generation of odorous gases in broiler sheds in order to understand the odour generation processes and the nature of the odorous gases generated on broiler farms. |
| Background | In order to develop effective odour control strategies for broiler farms, it is necessary to identify and characterise odour generation mechanisms in sheds. At the present time, odour neutralising agents and other additives are often used by farmers on a trial and error basis. An earlier study undertaken by the author identified ventilation rate as a particularly significant factor in controlling odour emission from broiler sheds. Consequently it can be expected that microbiological processes in sheds would be influenced by the magnitude and diurnal pattern of ventilation applied for temperature control, and the sensitivity and precision of manual or automatic control mechanisms adopted. |
| Research | The study attempted to identify and characterise odour generation mechanisms in the laboratory and in a typical broiler shed. In the laboratory, four reactors were set up to simulate aerobic and anaerobic conditions by feeding air and nitrogen gases through litter samples taken from sheds at six to seven weeks into a batch. Temperature, water content, pH, nitrogen content, carbon content, ammonia content and sulfide content in the litter were measured. Temperature, humidity, ammonia concentration, sulfide concentration, odour concentration and key odorous compounds in the exhaust were also measured. In the broiler shed itself, ammonia concentration, odour concentration, and key odorous compounds were measured weekly. At the same time, temperature, humidity and exhaust air velocity data monitored during the previous two weeks were downloaded. Ammonia concentration at the litter surface was also measured on a weekly basis. |
| Outcomes | Literature on ammonia and odour generation was researched and reviewed. Aerobic metabolism resulted in the production of breakdown products such as ammonia, water and carbon dioxide. Anaerobic metabolism produced intermediate products, such as volatile fatty acids (butyric acid, acetic acid), mercaptans (methyl mercaptan), sulfide containing compounds (hydrogen sulfide, dimethyl disulfide), nitrogen containing compounds (indole, ethylamine) and alcohols, along with the production of carbon dioxide and water. The optimum conditions for both aerobic and anaerobic microbial growth are discussed. |
| The laboratory results indicated
that ammonia concentrations under aerobic conditions were higher than under
anaerobic conditions. Soluble ammonia contents in the litter were lower
under aerobic conditions than under anaerobic conditions. This evidence
suggests that volatilisation of ammonia from the litter is a significant
factor in generating odour emission from broiler sheds. It is possible
that anaerobic conditions can lead to acidic conditions in the litter and
consequently limit volatilisation of ammonia from the litter. Odour concentrations
as well as sulfide concentration in the gas phase were observed to be higher
under anaerobic conditions than under aerobic conditions. No indication
of a correlation between odour and ammonia generation was found in the
study. The effects of temperature on the ammonia concentrations, sulfide
concentrations and odour concentrations were observed to be more significant
under anaerobic conditions than under aerobic conditions. Low litter pH
associated with high litter water content may indicate that the litter
in a shed is under anaerobic conditions.
The study has provided further evidence that biodegradation and volatilisation processes in boiler sheds are the two major odour generation mechanisms. In a typical shed, during weeks one to four of a batch, biodegradation under aerobic conditions can be expected to be the dominant process. By weeks five to seven of a batch, volatilisation processes are more significant than biodegradation processes. The study suggests that anaerobic processes in litter lead to a significant increase in the production of odorous compounds in the litter. Overall, odour emission from a broiler farm is driven primarily by ventilation at weeks five to seven which affects the volatilisation of odorous constituents from the litter. Consequently, it is concluded that odour emission rates from broiler farms after the first few weeks of growth are not significantly related to bird age but are primarily dependent on the diurnal pattern of ventilation rate. Results of the study also suggest that litter pH and water content measurements could be used as indicator parameters in managing odour on broiler farms. |
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| Implications | The water content and pH of litter may be able to be manipulated in order to reduce the magnitude of odour emission from broiler sheds. This could lead to the development of practical odour control strategies for broiler farms. |
| Project Title | Development of a new fowl pox vaccine strain |
| RIRDC Project No: | UQ-57A |
| Researcher: | Prof Wayne Robinson and Prof Peter Spradbrow |
| Organisation: | The University of Queensland
School of Veterinary Science and Animal Production BRISBANE QLD 4072 |
| Phone: | (07) 3365 2565 |
| Fax: | (07) 3365 1355 |
| Email: | p.spradbrow@mailbox.uq.edu.au |
| Objectives |
· To identify the factor or factors that have led to recent outbreaks of fowl pox in the face of vaccination. |
| Background | Fowl pox is a viral disease of great economic importance world wide. In Australia, the disease has been controlled by widespread vaccination of breeders and layers with live vaccines. However, in recent years fowl pox outbreaks have occurred on some commercial farms in NSW, most notably on one of the country’s largest breeder complexes. The re-emergence of fowl pox as a potential threat to the poultry industry prompted the industry to initiate a search for a new vaccine. |
| Research | In order to better understand
why the recent fowl pox problem had emerged, field isolates of Australian
fowl pox viruses, from recent outbreaks as well as earlier strains, were
collected and characterised. Characterisation included pathogenicity testing.
As it was considered that one of the factors that may have contributed
to vaccination failure may be immunosuppression due to retroviruses, all
of the collected field isolates and vaccine strains were screened for contamination
with reticuloendotheliosis virus (REV) using polymerase chain reaction
technology.
Work was undertaken to identify a field isolate(s) with potential for development into a new, more immunogenic vaccine. The two most promising candidate vaccine strains were evaluated in preliminary vaccinated trials in the laboratory. |
| Outcomes | Following extensive evaluation
of a large number of field isolates of fowl pox virus (FPV) from various
parts of Australia (NSW, VIC, QLD, WA) all were found to be contaminated
with the immunosuppressive virus reticuloendotheliosis virus (REV). In
addition, field isolates of fowl pox from NSW were more virulent when compared
to field isolates from other states. This was confirmed in a series of
laboratory trials where isolates from NSW were compared to field isolates
form other states and were found to give higher mortality rates in one-day-old
chickens. Infected chickens showed slow growth and had feathering defects.
They also had higher susceptibility to other diseases such as coccidiosis.
This was considered to be a combination of the virulence of the fowl pox
virus and its contamination with REV, which is known to cause, in susceptible
birds, stunted growth, feathering defects, high mortality and immunosuppression.
Furthermore, the research undertaken showed that currently used commercial fowl pox vaccines did not provide adequate protection for birds in NSW. When commercially available vaccines were used to vaccinate chickens, which were then challenged with field isolates, they were inefficient in providing good protection under the conditions of the experiments. Attempts to improve the immunogenicity of currently used commercial vaccines by repeated in vivo passages were unsuccessful. An isolate from Victoria was shown to give good protection in adult birds against challenge with field isolates and also against challenge with a vaccine strain (S-strain) that was withdrawn from commercial use because of its high level of virulence (80-100% mortality in day-old chicks). However, because the Victorian isolate contains REV, mortality was high (40%) when inoculated into one-day-old chickens. However, the surviving 60% developed an immunity against a challenge with a NSW field isolate, suggesting that the Victorian isolate has promise as a potential vaccine against FPV if it was restricted in use to older birds (six to eight weeks of age). |
| Implications | This investigation has provided
an improved understanding of the current fowl pox problem that has emerged
in some parts of the industry in Australia in recent years.
A field isolate from Victoria was identified which was shown to have considerable potential as an alternative, more immunogenic vaccine for fowl pox. However, because this isolate is contaminated with REV, further work will be required to develop it into a suitable commercial vaccine product. |
| Publications |
Diallo, I.S., Mackenzie, M.A., Spradbrow and Robinson, W.F. (1998) Field isolates of fowlpox virus contaminated with reticuloendotheliosis virus. Avian Pathology 27:60-66. |
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| Project Title | On farm comparison of computer controlled tunnel ventilated and naturally ventilated broiler sheds |
| RIRDC Project No: | DAN-40CM |
| Researcher: | Ms Anne Mabey |
| Organisation: | Department of Agriculture, NSW
CB Alexander Agricultural College, Tocal PATTERSON NSW 2421 |
| Phone: | (02) 4939 8888 |
| Fax: | (02) 4938 5549 |
| Email: | anne.mabey@agric.nsw.gov.au |
| Objective |
· To compare the performance of two commercial broiler shed designs. |
| Background | Like other Australian meat producing industries, the chicken meat industry needs to lower its cost of production to become globally competitive. A recent benchmark study by JT Larkin and SG Heilbron (1997), showed that the cost of production was 27% higher in Australia than in the USA or Thailand, but equivalent to the EU. To this end, chicken meat producers are looking at implementing measures that will increase their production efficiency. Tunnel ventilated sheds are seen as being one of the most efficient shed designs with increased stocking densities of up to 15% over current levels being proposed as feasible. |
| Research | This project was undertaken to compare the performance of tunnel ventilated sheds and the more widely used naturally ventilated sheds. Each shed was controlled by a Rotem computer which used temperature, humidity and air pressure sensors to automatically determine the best combination of settings of curtains, fans, misters and heaters to keep the shed at the target temperature. Target temperatures and ventilation levels were entered into the computer initially and then adjusted as necessary. Target temperatures gradually decreased from 33° C at day one to 20° C at day 55. Tunnel sheds operated in one of three modes, natural ventilation, minimum ventilation and, using one or more of the seven tunnel fans, tunnel mode. Naturally ventilated sheds basically operated in one mode, natural ventilation assisted by stirrer fans. |
| Outcomes | The best indicator of performance
is return per bird, which encompasses mortality, feed conversion and other
parameters. Return per bird did not differ significantly between tunnel
ventilated (49.6c) and naturally ventilated (49.1c) sheds over 13 batches.
Return per bird, however, did differ significantly over the five summer
batches, the tunnel sheds returned 50.379c per bird while the naturally
ventilated sheds returned 49.317c per bird. A recent pool ranking of 88
growers by the processing company placed the tunnel ventilated sheds at
fourth position and the naturally ventilated sheds at eleventh, consistent
with the tunnel sheds performing slightly better than the other sheds based
on corrected feed conversion rations.
Temperature control was better in the tunnel sheds than the naturally ventilated sheds, especially during the hotter months. The cost of heating during brooding and the cost of electricity were significantly higher for the tunnel sheds. Corrected for the difference in shed size, tunnel sheds were on average $177/shed more expensive to run per batch than naturally ventilated sheds. This extra cost is nearly cancelled by the slightly increased return per bird for the tunnel sheds of approximately $93/shed per batch. |
| Implications | With effective management naturally ventilated sheds perform nearly as well as tunnel sheds. Tunnel sheds however maintain a cooler climate during hot climatic conditions and are easier to manage and work in. Although running costs of the tunnel sheds were slightly higher than for naturally ventilated sheds over the 13 batches of this trial, computer controlled tunnel sheds are still considered the best shedding option. |
 
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