Food-borne pathogens and pig waste products - the spoke in the wheel?

Food-borne pathogens are present in normal healthy pigs and thus are also present in pig wastes and by-products. The presence of these pathogens can be viewed negatively (i.e. 'a spoke in the wheel') or as simply another issue that requires the adoption of appropriate guidelines and management procedures. A key component in the development of appropriate, effective guidelines and management practices is a solid basis of knowledge on which pathogens are present as well as the levels of these pathogens. This paper reviews Australian Pork Limited (APL) funded projects carried out in our laboratories that have provided a solid base of Australian data for the pig industry. These data will ensure that pathogens are not 'a spoke in the wheel' but rather an issue - like many others that confront the industry - that can be managed to ensure that there is no unacceptable risk to either public health or the environment.

Global banana disease management - getting serious with sustainability and food security

Much research in understanding plant diseases has been undertaken, but there has been insufficient attention given to dealing with coordinated approaches to preventing and managing diseases. A global management approach is essential to the long-term sustainability of banana production. This approach would involve coordinated surveys, capacity building in developing countries, development of disease outbreak contingency plans and coordinated quarantine awareness, including on-line training in impact risk assessment and web-based diagnostic software. Free movement of banana plants and products between some banana-producing countries is causing significant pressure on the ability to manage diseases in banana. The rapid spread of Fusarium oxysporum f. sp. cubense 'tropical race 4' in Asia, bacterial wilts in Africa and Asia and black leaf streak [Mycosphaerella fijiensis] in Brazil and elsewhere are cases in point. The impact of these diseases is devastating, severely cutting family incomes and jeopardising food security around the globe. Agreements urgently need to be reached between governments to halt the movement of banana plants and products between banana-producing countries before it is too late and global food security is irreparably harmed. Black leaf streak, arguably the most serious banana disease, has become extremely difficult to control in commercial plantations in various parts of the world. Sometimes in excess of 50 fungicide sprays have to be applied each year. Disease eradication and effective disease control is not possible because there is no control of disease inoculum in non-commercial plantings in these locations. Additionally, there have been enormous sums of money invested in international banana breeding programmes over many years only to see the value of hybrid products lost too soon. 'Goldfinger' (AAAB, syn. 'FHIA-01'), for example, has recently been observed severely affected by black leaf streak in Samoa. Resistant cultivars alone cannot be relied upon in the fight against this disease. Real progress in control may only come when the local communities are engaged and become actively involved in regional programmes. Global recommendations are long overdue and urgently needed to help ensure the long-term sustainable utilisation of the products of the breeding programmes.

Hydrogen utilising bacteria from the forestomach of eastern grey (Macropus giganteus) and red (Macropus rufus) kangaroos

Reductive acetogenesis is an alternative to methanogenesis for removing hydrogen produced during enteric fermentation. In Australia, kangaroos have evolved an enlarged forestomach analogous to the rumen of sheep and cattle. However, unlike sheep and cattle, kangaroos produce very little methane from enteric fermentation. From samples of gut contents from five eastern grey and three red kangaroos, we were not able to detect methanogens using a PCR protocol, but did detect the formyltetrahydrofolate synthetase (FTHFS) gene (likely to be used for reductive acetogenesis) in all animals. Isolations to recover acetogens resulted in two different classes of hydrogen consuming bacteria being isolated. The first class consisted of acetogens that possessed the FTHFS gene, which except for Clostridium glycolicum, were not closely related to any previously cultured bacteria. The second class were not acetogens but consisted of enterobacteria (Escherichia coli and Shigella) that did not possess FTHFS genes but did utilise hydrogen and produce acetate. Enumeration of the acetogens containing the FTHFS gene by real-time PCR indicated that bacteria of the taxa designated YE257 were common to all the kangaroos whereas YE266/YE273 were only detected in eastern grey kangaroos. When present, both species occurred at densities above *106 cell equivalents per mL. C. glycolicum was not detected in the kangaroos and, unlike YE257 and YE266/273, is unlikely to play a major role in reductive acetogenesis in the foregut of kangaroos.

Stochastic demography and population dynamics in the red kangaroo Macropus rufus

1. Many organisms inhabit strongly fluctuating environments but their demography and population dynamics are often analysed using deterministic models and elasticity analysis, where elasticity is defined as the proportional change in population growth rate caused by a proportional change in a vital rate. Deterministic analyses may not necessarily be informative because large variation in a vital rate with a small deterministic elasticity may affect the population growth rate more than a small change in a less variable vital rate having high deterministic elasticity. 2. We analyse a stochastic environment model of the red kangaroo (Macropus rufus), a species inhabiting an environment characterized by unpredictable and highly variable rainfall, and calculate the elasticity of the stochastic growth rate with respect to the mean and variability in vital rates. 3. Juvenile survival is the most variable vital rate but a proportional change in the mean adult survival rate has a much stronger effect on the stochastic growth rate. 4. Even if changes in average rainfall have a larger impact on population growth rate, increased variability in rainfall may still be important also in long-lived species. The elasticity with respect to the standard deviation of rainfall is comparable to the mean elasticities of all vital rates but the survival in age class 3 because increased variation in rainfall affects both the mean and variability of vital rates. 5. Red kangaroos are harvested and, under the current rainfall pattern, an annual harvest fraction of c. 20% would yield a stochastic growth rate about unity. However, if average rainfall drops by more than c. 10%, any level of harvesting may be unsustainable, emphasizing the need for integrating climate change predictions in population management and increase our understanding of how environmental stochasticity translates into population growth rate.

An improved technique for estimating short-term survival of released line-caught fish, and an application comparing barotrauma-relief methods in red emperor (Lutjanus sebae Cuvier 1816).

Promotion of better procedures for releasing undersize fish, advocacy of catch-and-release angling, and changing minimum legal sizes are increasingly being used as tools for sustainable management of fish stocks. However without knowing the proportion of released fish that survive, the conservation value of any of these measures is uncertain. We developed a floating vertical enclosure to estimate short-term survival of released line-caught tropical and subtropical reef-associated species, and used it to compare the effectiveness of two barotrauma-relief procedures (venting and shotline releasing) on red emperor (Lutjanus sebae). Barotrauma signs varied with capture depth, but not with the size of the fish. Fish from the greatest depths (40-52 m) exhibited extreme signs less frequently than did those from intermediate depths (30-40 m), possibly as a result of swim bladder gas being vented externally through a rupture in the body wall. All but two fish survived the experiment, and as neither release technique significantly improved short-term survival of the red emperor over non-treatment we see little benefit in promoting either venting or shotline releasing for this comparatively resilient species. Floating vertical enclosures can improve short-term post-release mortality estimates as they overcome many problems encountered when constraining fish in submerged cages.

The performance of irrigated mixtures of tall fescue, ryegrass and white clover in subtropical Australia. 1. The effects of sowing mixture combinations, nitrogen and oversowing on establishment, productivity, botanical composition and persistence.

In the subtropics of Australia, the ryegrass component of irrigated perennial ryegrass (Lolium perenne) - white clover (Trifolium repens) pastures declines by approximately 40% in the summer following establishment, being replaced by summer-active C4 grasses. Tall fescue (Festuca arundinacea) is more persistent than perennial ryegrass and might resist this invasion, although tall fescue does not compete vigorously as a seedling. This series of experiments investigated the influence of ryegrass and tall fescue genotype, sowing time and sowing mixture as a means of improving tall fescue establishment and the productivity and persistence of tall fescue, ryegrass and white clover-based mixtures in a subtropical environment. Tall fescue frequency at the end of the establishment year decreased as the number of companion species sown in the mixture increased. Neither sowing mixture combinations nor sowing rates influenced overall pasture yield (of around 14 t/ha) in the establishment year but had a significant effect on botanical composition and component yields. Perennial ryegrass was less competitive than short-rotation ryegrass, increasing first-year yields of tall fescue by 40% in one experiment and by 10% in another but total yield was unaffected. The higher establishment-year yield (3.5 t/ha) allowed Dovey tall fescue to compete more successfully with the remaining pasture components than Vulcan (1.4 t/ha). Sowing 2 ryegrass cultivars in the mixture reduced tall fescue yields by 30% compared with a single ryegrass (1.6 t/ha), although tall fescue alone achieved higher yields (7.1 t/ha). Component sowing rate had little influence on composition or yield. Oversowing the ryegrass component into a 6-week-old sward of tall fescue and white clover improved tall fescue, white clover and overall yields in the establishment year by 83, 17 and 11%, respectively, but reduced ryegrass yields by 40%. The inclusion of red (T. pratense) and Persian (T. resupinatum) clovers and chicory (Cichorium intybus) increased first-year yields by 25% but suppressed perennial grass and clover components. Yields were generally maintained at around 12 t/ha/yr in the second and third years, with tall fescue becoming dominant in all 3 experiments. The lower tall fescue seeding rate used in the first experiment resulted in tall fescue dominance in the second year following establishment, whereas in Experiments 2 and 3 dominance occurred by the end of the first year. Invasion by the C4 grasses was relatively minor (<10%) even in the third year. As ryegrass plants died, tall fescue and, to a lesser extent, white clover increased as a proportion of the total sward. Treatment effects continued into the second, but rarely the third, year and mostly affected the yield of one of the components rather than total cumulative yield. Once tall fescue became dominant, it was difficult to re-introduce other pasture components, even following removal of foliage and moderate renovation. Severe renovation (reducing the tall fescue population by at least 30%) seems a possible option for redressing this situation.

Assessing the effects of line capture and barotrauma relief procedures on post-release survival of key tropical reef fish species in Australia using recreational tagging clubs.

Common coral trout, Plectropomus leopardus Lacepede, crimson snapper, Lutjanus erythropterus Bloch, saddletail snapper, Lutjanus malabaricus (Bloch & Schneider), red emperor, Lutjanus sebae (Cuvier), redthroat emperor, Lethrinus miniatus (Schneider) and grass emperor, Lethrinus laticaudis Alleyne & Macleay, were tagged to determine the effects of barotrauma relief procedures (weighted shot-line release and venting using a hollow needle) and other factors on survival. Release condition was the most significant factor affecting the subsequent recapture rate of all species. Capture depth was significant in all species apart from L. malabaricus and L. miniatus, the general trend being reduced recapture probability with increasing capture depth. Recapture rates of fish hooked in either the lip or mouth were generally significantly higher than for those hooked in the throat or gut. Statistically significant benefit from treating fish for barotrauma was found in only L. malabaricus, but the lack of any negative effects of treating fish indicated that the practices of venting and shot-lining should not be discouraged by fisheries managers for these species.

Increased reproductive success in older female red kangaroos and the impact of harvesting

Wildlife harvesting has a long history in Australia, including obvious examples of overexploitation. Not surprisingly, there is scepticism that commercial harvesting can be undertaken sustainably. Kangaroo harvesting has been challenged regularly at Administrative Appeals Tribunals and elsewhere over the past three decades. Initially, the concern from conservation groups was sustainability of the harvest. This has been addressed through regular, direct monitoring that now spans > 30 years and a conservative harvest regime with a low risk of overharvest in the face of uncertainty. Opposition to the harvest now continues from animal rights groups whose concerns have shifted from overall harvest sustainability to side effects such as animal welfare, and changes to community structure, genetic composition and population age structure. Many of these concerns are speculative and difficult to address, requiring expensive data. One concern is that older females are the more successful breeders and teach their daughters optimal habitat and diet selection. The lack of older animals in a harvested population may reduce the fitness of the remaining individuals; implying population viability would also be compromised. This argument can be countered by the persistence of populations under harvesting without any obvious impairment to reproduction. Nevertheless, an interesting question is how age influences reproductive output. In this study, data collected from a number of red kangaroo populations across eastern Australia indicate that the breeding success of older females is up to 7-20% higher than that of younger females. This effect is smaller than that of body condition and the environment, which can increase breeding success by up to 30% and 60% respectively. Average age of mature females in a population may be reduced from 9 to 6 years old, resulting in a potential reduction in breeding success of 3-4%. This appears to be offset in harvested populations by improved condition of females from a reduction in kangaroo density. There is an important recommendation for management. The best insurance policy against overharvest and unwanted side effects is not research, which could be never-ending. Rather, it is a harvest strategy that includes safeguards against uncertainty such as harvest reserves, conservative quotas and regular monitoring. Research is still important in fine tuning that strategy and is most usefully incorporated as adaptive management where it can address the key questions on how populations respond to harvesting.

Presence and incidence of food-borne pathogens in Australian chicken litter.

1. Litter samples were collected at the end of the production cycle from spread litter in a single shed from each of 28 farms distributed across the three Eastern seaboard States of Australia. 2. The geometric mean for Salmonella was 44 Most Probable Number (MPN)/g for the 20 positive samples. Five samples were between 100 and 1000 MPN/g and one at 105 MPN/g, indicating a range of factors are contributing to these varying loads of this organism in litter. 3. The geometric mean for Campylobacter was 30 MPN/g for the 10 positive samples, with 7 of these samples being 100 MPN/g. The low prevalence and incidence of Campylobacter were possibly due to the rapid die-off of this organism. 4. E. coli values were markedly higher than the two key pathogens (geometric mean 20 x 105 colony forming units (cfu)/g) with overall values being more or less within the same range across all samples in the trial, suggesting a uniform contribution pattern of these organisms in litter. 5. Listeria monocytogenes was absent in all samples and this organism appears not to be an issue in litter. 6. The dominant (70% of the isolates) Salmonella serovar was S. Sofia (a common serovar isolated from chickens in Australia) and was isolated across all regions. Other major serovars were S. Virchow and S. Chester (at 10%) and S. Bovismorbificans and S. Infantis (at 8%) with these serovars demonstrating a spatial distribution across the major regions tested. 7. There is potential to re-use litter in the environment depending on end use and the support of relevant application practices and guidelines.

Norsesquiterpene Glycosides in Bracken Ferns (Pteridium esculentum and Pteridium aquilinum subsp wightianum) from Eastern Australia: Reassessed Poisoning Risk to Animals.

Austral bracken Pteridium esculentum contains three unstable norsesquiterpene glycosides: ptaquiloside, ptesculento-side, and caudatoside, in variable proportions. The concentration of each of the glycosides was determined in this study as their respective degradation products, pterosin B, pterosin G and pterosin A, by HPLC-UV analysis. Samples of P. esculentum collected from six sites in eastern Australia contained up to 17 mg of total glycoside/g DW, with both ptaquiloside and ptesculentoside present as major components accompanied by smaller amounts of caudatoside. Ratios of ptaquiloside to ptesculentoside varied from 1:3 to 4:3, but in all Australian samples ptesculentoside was a significant component. This profile differed substantially from that of P. esculentum from New Zealand, which contained only small amounts of both ptesculentoside and caudatoside, with ptaquiloside as the dominant component. A similar profile with ptaquiloside as the dominant glycoside was obtained for Pteridium aquilinum subsp. wightianum (previously P. revolutum) from northern Queensland and also P. aquilinum from European sources. Ptesculentoside has chemical reactivity similar to that of ptaquiloside and presumably biological activity similar to that of this potent carcinogen. The presence of this additional reactive glycoside in Australian P. esculentum implies greater toxicity for consuming animals than previously estimated from ptaquiloside content alone.

North Queensland Food Industry Development

Provision of food industry development advice, guidance, and NATA microbiological testing service to the North Queensland food industry in 2008/2009.

BA09025 Commercial feasibility of banana waste utilization in food industry

As a response to the HAL banana call, this project will look to further utilization of bananas not suitable for the retail market.

Screening of new lines of cereal grains for inclusion in Near Infra Red Scan calibrations

The project will provide enough data for a reliable and robust NIRs. It will more fully develop the in vitro method to enable less costly assessment of grains in the future. It will also provide a reliable assessment for DE which is the most expensive component of pig feed.

Sustaining productivity of tropical red snappers using new monitoring and reference points

OBJECTIVES: 1. Analyse current monitoring and logbook data sets, as well as survey and other information,to establish whether these data provide sufficient power to develop critical indicators of fishery performance. 2. Provide a risk analysis that examines the use of age structure and catch rate information for development of critical indicators, and response rules for those criteria, in the absence of other fishery information. 3. Develop a monitoring program that uses commercial vessels from the fishery to provide independent data.

ACIAR Scoping study for Improved food security and livelihoods in rural Zimbabwe

A short project to provide input to planning a project aimed at improving food security and rural livelihoods in Zimbabwe.