Salmonella and on-farm risk factors in healthy slaughter-age cattle and sheep in eastern Australia

To examine healthy slaughter-age cattle and sheep on-farm for the excretion of Salmonella serovars in faeces and to identify possible risk factors using a questionnaire. The study involved 215 herds and flocks in the four eastern states of Australia, 56 with prior history of salmonellosis. Production systems examined included pasture beef cattle, feedlot beef cattle, dairy cattle, prime lambs and mutton sheep and animals were all at slaughter age. From each herd or flock, 25 animals were sampled and the samples pooled for Salmonella culture. All Salmonella isolated were serotyped and any Salmonella Typhimurium isolates were phage typed. Questionnaires on each production system, prepared in Epi Info 6.04, were designed to identify risk factors associated with Salmonella spp excretion, with separate questionnaires designed for each production system. Salmonellae were identified in all production systems and were more commonly isolated from dairies and beef feedlots than other systems. Statistical analysis revealed that dairy cattle were significantly more likely to shed Salmonella in faeces than pasture beef cattle, mutton sheep and prime lambs (P < 0.05). A wide diversity of Salmonella serovars, all of which have been isolated from humans in Australia, was identified in both cattle and sheep. Analysis of the questionnaires showed access to new arrivals was a significant risk factor for Salmonella excretion on dairy properties. For beef feedlots, the presence of large numbers of flies in the feedlot pens or around stored manure were significant risk factors for Salmonella excretion. Dairy cattle pose the highest risk of all the slaughter-age animals tested. Some of the identified risk factors can be overcome by improved management practices, especially in relation to hygiene.

Development of a model based on Bayesian networks to estimate the probability of sheep lice presence at shearing

This paper describes the development of a model, based on Bayesian networks, to estimate the likelihood that sheep flocks are infested with lice at shearing and to assist farm managers or advisers to assess whether or not to apply a lousicide treatment. The risk of lice comes from three main sources: (i) lice may have been present at the previous shearing and not eradicated; (ii) lice may have been introduced with purchased sheep; and (iii) lice may have entered with strays. A Bayesian network is used to assess the probability of each of these events independently and combine them for an overall assessment. Rubbing is a common indicator of lice but there are other causes too. If rubbing has been observed, an additional Bayesian network is used to assess the probability that lice are the cause. The presence or absence of rubbing and its possible cause are combined with these networks to improve the overall risk assessment.

Issues and advances in the integrated control of sheep lice.

Ongoing pressure to minimise costs of production, growing markets for low residue and organic wool and meat, resistance to chemicals in louse populations, and the deregistration of diazinon for dipping and jetting have contributed to a move away from routine annual application of lousicides to more integrated approaches to controlling lice. Advances including improved methods for monitoring and detection of lice, an expanded range of louse control products and the availability of a web-accessible suite of decision support tools for wool growers (LiceBossTM) will aid this transition. Possibilities for the future include an on-farm detection test and non-chemical control methods. The design and extension of well-constructed resistance management programs to preserve the effectiveness of recently available new product groups should be a priority.

Leading Sheep III

Leading Sheep is a framework for supporting decision-making about technologies and practices to increase the profitability and productivity of the Queensland Sheep Businesses. Leading Sheep aims to achieve a high level of engagement with sheep businesses in Queensland to support their ongoing decision making processes about productivity and profitability.

Making More from Sheep Phase II : MMfS State Coordination – Queensland

Making More from Sheep (MMfS) is a majority market extension program funded by Meat & Livestock Australia (MLA) and Australian Wool Innovation (AWI). Phase II of MMfS commenced in Queensland with a business planning process in October 2010 and delivery from November 2010 until November 2013. Mr Tony Hamilton of the Department of Agriculture, Fisheries and Forestry (DAFF) was initially the State Coordinator with responsibility for planning, project implementation, monitoring and evaluation. He was replaced by Ms Nicole Sallur from DAFF towards the end of the project. Delivery involving partner organisations provided best practice management information and tools to sheep producers with target Key Performance Indicators (KPI’s) exceeded across all three tiers of engagement category. 31 events were delivered to 551 participants. Satisfaction and value scores averaged across all events measured 8.7 and 8.2 respectively. Operational recommendations have been included in the report.

Ecology of uncultivated oscillospira species in the rumen of cattle, sheep, and reindeer as assessed by microscopy and molecular approaches

The ecology of the uncultured, but large and morphologically conspicuous, rumen bacterium Oscillospira spp. was studied. Oscillospira-specific 16S rRNA gene sequences were detected in North American domestic cattle, sheep from Australia and Japan, and Norwegian reindeer. Phylogenetic analysis of the sequences obtained allowed definition of three operational taxonomic units within the Oscillospira clade. Consistent with this genetic diversity, we observed atypical smaller morphotypes by using an Oscillospira-specific fluorescence in situ hybridization probe. Despite the visual disappearance of typical large Oscillospira morphotypes, the presence of Oscillospira spp. was still detected by Oscillospira-specific PCR in the rumen of cattle and sheep. These observations suggest the broad presence of Oscillospira species in various rumen ecosystems with the level, and most likely the morphological form, dependent on diet. An ecological analysis based on enumeration of the morphologically conspicuous, large-septate form confirms that the highest counts are associated with the feeding of fresh forage diets to cattle and sheep and in two different subspecies of reindeer investigated.

Composition of chemical attractants affects trap catches of the Australian sheep blowfly, lucilia cuprina, and other blowflies

Numbers of Lucilia cuprina (Australian sheep blowfly), Chrysomya spp., and Calliphora spp. blowflies caught on sticky traps baited with various synthetic attractants or a standard liver/sodium sulfide attractant in western Queensland were recorded. Numbers of each genus collected were influenced by the composition of the chemical attractants. Attractant mixtures based on 2-mercaptoethanol, indole, butanoic/pentanoic acid, and a sodium sulfide solution gave 5- to 20-fold higher L. cuprina catches than the liver standard. These blends attracted similar numbers of Chrysomya spp. (0.85–2.7× ) and fewer Calliphora spp. (0.02–0.2× ) compared to the liver standard. These synthetic attractants were more effective and selective for L. cuprina than the standard liver/sodium sulfide attractant, and they can be packaged in controlled-release dispensers to generate constant, prolonged release of the attractant.

Effect of seasonal conditions on fleece weight and its components in merino sheep grazing Mitchell grass pasture in North West Queensland

SUMMARY Seasonal conditions in the pre to post natal period and selected periods before and during wool growth were described using climatic measures and estimates of the quality and quantity of pasture on offer derived from a validated pasture production model (GRASP). The variation in greasy and clean fleece weight, yield, staple length, fibre diameter, neck and side wrinkle score of Merinos grazing Mitchell grass in north west Queensland was explained in terms of these pasture and climatic measures and animal characteristics such as reproductive status, age and skin area. Multiple regression equations predicting clean and greasy fleece weight from the proportion of days in the wool growth period that the green pool in the pasture was less than one kg/ha, the percentage utilisation of the pasture, age, reproductive status and skin area of the ewes explained 87% and 79% of the variation respectively. Equations with similar predictors explained 58-85% of the variation of the other components. The inclusion of pasture conditions in the pre to post natal period did not significantly improve the predictions of the animal’s later performance. 22nd Biennial Conference.

Adaptability of Damara, Dorper and Traditional Meat Sheep Breeds in Semi-Arid Queensland

Reproductive rate is a major contributing factor to the profitability of a sheep meat enterprise. Low reproduction rate is a feature of sheep husbandry in semi-arid Queensland. High ambient temperatures are implicated in poor fertility (Moule 1970) where variation in response can be due to breed and to animals within a breed (Hopkins and Stephenson 1978). Breeds recently imported from South Africa were selected in arid environments and may be better adapted to pastoral conditions of northern Australia than traditional breeds. Animal production for a consuming world : proceedings of 9th Congress of the Asian-Australasian Association of Animal Production Societies [AAAP] and 23rd Biennial Conference of the Australian Society of Animal Production [ASAP] and 17th Annual Symposium of the University of Sydney, Dairy Research Foundation, [DRF]. 2-7 July 2000, Sydney, Australia. This study will investigate (a) the thermoregulatory ability of Damara, Dorper, Poll Dorset, Rambouillet, South African Meat Merino and Queensland medium wool Merino rams prior to joinings in the autumn and spring of 1999, 2000 and 2001 and (b) the association between thermoregulatory parameters (rectal temperature and respiration rate) and ewe fertility. Results for the initial autumn joining are reported in this paper.

Supply capability of sheep on the Mitchell grass downs of North and Central West Queensland

While, in the past, sheep have been predominantly reared and grazed in western Queensland for wool, interest in the sheep meat industry increased when wool prices became depressed. For north west and central west Queensland producers, opportunities may exist to participate in live sheep and meat export to Asia. The capability of the Mitchell grass downs to provide sufficient numbers of export quality sheep under the variable climatic conditions while sustaining the land resources has been simulated. Sheep numbers were found to be insufficient to maintain a consistent supply for live export. However, raising marking rates and lowering mortalities effectively increased reproductive performance to a level at which a surplus for export could be sustainable. Other practices might be required for the liveweight specifications to be met. 24th Biennial Conference. Adelaide, South Australia.

Simulation of the supply capability of sheep on the Mitchell grass downs of north west Queensland

Sheep in western Queensland have been predominantly reared for wool. When wool prices became depressed interest in the sheep meat industry, increased. For north west Queensland producers, opportunities may exist to participate in live sheep and meat export to Asia. A simulation model was developed to determine whether this sheep producing area has the capability to provide sufficient numbers of sheep under variable climatic conditions while sustaining the land resources. Maximum capacity for sustainability of resources (as described by stock numbers) was derived from an in-depth study of the agricultural and pastoral potential of Queensland. Decades of sheep production and climatic data spanning differing seasonal conditions were collated for analysis. A ruminant biology model adapted from Grazplan was used to simulate pregnancy rate. Empirical equations predict mortalities, marking rates, and weight characteristics of sheep of various ages from simple climatic measures, stocking rate and reproductive status. The initial age structure of flocks was determined by running the model for several years with historical climatic conditions. Drought management strategies such as selling a proportion of wethers progressively down to two-tooth and oldest ewes were incorporated. Management decisions such as time of joining, age at which ewes were cast-for-age, wether turn-off age and turning-off rate of lambs vary with geographical area and can be specified at run time. The model is run for sequences of climatic conditions generated stochastically from distributions based on historical climatic data correlated in some instances. The model highlights the difficulties of sustaining a consistent supply of sheep under variable climatic conditions.

Modelling Mortality and Reproduction Rates for Management of Sheep Flocks in Northern Australia

By quantifying the effects of climatic variability in the sheep grazing lands of north western and western Queensland, the key biological rates of mortality and reproduction can be predicted for sheep. These rates are essential components of a decision support package which can prove a useful management tool for producers, especially if they can easily obtain the necessary predictors. When the sub-models of the GRAZPLAN ruminant biology process model were re-parameterised from Queensland data along with an empirical equation predicting the probability of ewes mating added, the process model predicted the probability of pregnancy well (86% variation explained). Predicting mortality from GRAZPLAN was less successful but an empirical equation based on relative condition of the animal (a measure based on liveweight), pregnancy status and age explained 78% of the variation in mortalities. A crucial predictor in these models was liveweight which is not often recorded on producer properties. Empirical models based on climatic and pasture conditions estimated from the pasture production model GRASP, predicted marking and mortality rates for Mitchell grass (Astrebla sp.) pastures (81% and 63% of the variation explained). These prediction equations were tested against independent data from producer properties and the model successfully validated for Mitchell grass communities.

Identification and preliminary evaluation of viriditoxin, a metabolite of Paecilomyces varioti, as an insecticide for sheep blowfly, Lucilia cuprina (Wied.)

Solvent extracts of cultures of the fungus Paecilomyces varioti are toxic to sheep blowfly, Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae). Different components of the culture extracts were isolated and bioassayed with L. cuprina. The component with most toxicity was purified and identified from its proton magnetic resonance spectrum as viriditoxin, a known antibiotic metabolite of the fungus. The insecticidal properties of viriditoxin were then evaluated. Mean LCso values for first instar larvae of organophosphate susceptible and resistant strains of L. cuprina were 7.5 and 8.4 ppm respectively. Pilot implant trials in sheep demonstrated that the compound provided protection for 9-17 weeks against both strains of L. cuprina. No adverse effects on the trial sheep were detected.

Improving sheep feedlot management

This paper summarise six studies undertaken by the Sheep CRC to elucidate certain aspects of confinement feeding of sheep. A review of confinement feeding highlighted the variability of growth rate and feed conversion of sheep and revealed that little is known about the use of sorghum for feeding sheep. The review indicated that the main factors responsible for variation of growth rate and feed conversion were adaptation to grain and feeding system, including the preparation and presentation of feed. The importance of social and physiological adaptation to grain feeding was confirmed. Factors identified as responsible for safe induction and uniform growth rates included prior exposure to grain as lambs, gradual introduction of grain and, when concentrate was provided ad libitum from the first day, the use of either virginiamycin, a pelleted feed, a total mixed ration or a step-wise increase of high-starch grain components. Separate feeding of hay and grain resulted in performance comparable with that of a pelleted diet and that of a total mixed ration. Sorghum-based concentrate diets resulted in growth rates and carcase weights similar to that for winter cereal grains or pellets. Steam flaking or expanding of sorghum had no significant effect on growth rates or carcase weights. These results can be used to determine the profitability of various feedlotting options.

Using immunology and resistant sheep to beat the fly

New methods for controlling blowfly strike will be needed when mulesing is phased out and the availability or efficacy of insecticides for control of fly strike decreases. The Australian Sheep Industry CRC has pursued two approaches for the development of new methods to help control blowfly strike. In the first, genetic resistance of sheep to survival and growth of blowfly larvae was examined. Resistance to growth of larvae was heritable (0.29 ± 0.22). The trait was not associated with resistance to internal parasites, nor was it influenced by wool characteristics such as fibre diameter or coefficient of variation of fibre diameter. This new trait differs from resistance to fly strike associated with resistance to fleece rot. Because measurement of the trait is labour intensive, gene markers or correlated measures are needed before it will be suitable for industry adoption. The second approach examined the impact of larval products on the immmune system of the sheep. Larvae suppress the sheep immune system and thereby limit the ability of the sheep to reject the larvae. The immunosuppresive agent is being purified and strategies to abolish its activity are being explored. Abolition of immunosuppression would create opportunities for the development of new vaccines againts blowfly strike.