Regrouping unfamiliar animals in the weeks prior to slaughter has few effects on physiology and meat quality in Bos taurus feedlot steers

The response of cattle to alterations in social groupings can lead to physiological changes that affect meat quality. Feedlot practices frequently lead to a proportion of cattle in a pen being drafted for slaughter with the balance retained for a further period until they meet market specifications. An ability to regroup such retained cattle for short periods without consequences for meat quality would facilitate efficient use of feedlot pen space. The current experiment examined the impact on physiological variables and meat quality of regrouped British breed steers 4, 2 or 1 week before dispatch for slaughter. There was little effect of regrouping cattle on physiological variables associated with stress responses. Physical assessment of meat quality indicated that regrouping steers 1 week before slaughter led to higher compression and a tendency for higher peak force values in animals from one genotype than in their respective controls (1.89 v. 1.71 ± 0.05 kg, P = 0.017); however, these assessments were not matched by changes in sensory perception of meat quality. Average daily gain during feedlot finishing was negatively related to the temperament measure and flight time. It was also associated with breed, white cell count, plasma cortisol and haemoglobin at the midpoint of the 70-day finishing period. The results confirm the impact of flight time on growth rate during feedlot finishing and that regrouping cattle less than 2 weeks before slaughter may reduce meat quality.

Herpesviral haematopoietic necrosis virus (CyHV-2) infection: case studies from commercial goldfish farms

Herpesviral haematopoietic necrosis is a disease of goldfish, Carassius auratus, caused by Cyprinid herpesvirus-2 (CyHV-2) infection. Quantitative PCR was carried out on tissue homogenates from healthy goldfish fingerlings, broodfish, eggs and fry directly sampled from commercial farms, from moribund fish submitted to our laboratory for disease diagnosis, and on naturally-infected CyHV-2 carriers subjected to experimental stress treatments. Healthy fish from 14 of 18 farms were positive with copy numbers ranging from tens to 10(7) copies mu g(-1) DNA extracted from infected fish. Of 118 pools of broodfish tested, 42 were positive. The CyHV-2 was detected in one lot of fry produced from disinfected eggs. Testing of moribund goldfish, in which we could not detect any other pathogens, produced 12 of 30 cases with 10(6)-10(8) copies of CyHV-2 mu g(-1) DNA extracted. Subjecting healthy CyHV-2 carriers to cold shock (22-10 degrees C) but not heat, ammonia or high pH, increased viral copy numbers from mean copy number (+/- SE) of 7.3 +/- 11 to 394 +/- 55 mu g(-1) DNA extracted after 24 h. CyHV-2 is widespread on commercial goldfish farms and outbreaks apparently occur when healthy carriers are subjected to a sharp temperature drop followed by holding at the permissive temperature for the disease.

Co-evolution of wild rabbits (Oryctolagus cuniculus) and RHDV: resistance and virulence

Rabbit Haemorrhagic Disease Virus (RHDV) was introduced to Australia in 1995 for the control of wild rabbits. Initial outbreaks greatly reduced rabbit numbers and the virus has continued to control rabbits to varying degrees in different parts of Australia. However, recent field evidence suggests that the virus may be becoming less effective in those areas that have previously experienced repeated epizootics causing high mortality. There are also reports of rabbits returning to pre-1995 density levels, Virus and host can be expected to co-evolve. The host will develop resistance to the virus with the virus subsequently changing to overcome that resistance. It has been 12 years since the release of RHDV and it is an opportune time to examine where the dynamic currently stands between RHDV and rabbits. Laboratory challenge tests have indicated that resistance to RHDV has developed to different degrees in populations throughout Australia. In one population a low dose (1:25 dilution) of Czech strain RHDV failed to infect a single susceptible rabbit, yet infected a low to high (up to 73%) percentage across other populations tested. Different selection pressures are present in these populations and will be driving the level of resistance being seen. The mechanisms and genetics behind the development of resistance are also important as the on-going use of RHDV as a control tool in the management of rabbits relies on our understanding of factors influencing the efficacy of the virus. Understanding how resistance has developed may provide clues on how best to use the virus to circumvent these mechanisms. Similarly, it will help in managing populations that have yet to develop high levels of resistance.

Assessing the taxonomic status of dingoes Canis familiaris for conservation

1. The conservation status of the dingo Canis familiaris dingo is threatened by hybridization with the domestic dog C. familiaris familiaris. A practical method that can estimate the different levels of hybridization in the field is urgently required so that animals below a specific threshold of dingo ancestry (e.g. 1/4 or 1/2 dingoes) can reliably be identified and removed from dingo populations. 2. Skull morphology has been traditionally used to assess dingo purity, but this method does not discriminate between the different levels of dingo ancestry in hybrids. Furthermore, measurements can only be reliably taken from the skulls of dead animals. 3. Methods based on the analysis of variation in DNA are able to discriminate between the different levels of hybridization, but the validity of this method has been questioned because the materials currently used as a reference for dingoes are from captive animals of unproven genetic purity. The use of pre-European materials would improve the accuracy of this method, but suitable material has not been found in sufficient quantity to develop a reliable reference population. Furthermore, current methods based on DNA are impractical for the field-based discrimination of hybrids because samples require laboratory analysis. 4. Coat colour has also been used to estimate the extent of hybridization and is possibly the most practical method to apply in the field. However, this method may not be as powerful as genetic or morphological analyses because some hybrids (e.g. Australian cattle dog × dingo) are similar to dingoes in coat colour and body form. This problem may be alleviated by using additional visual characteristics such as the presence/absence of ticking and white markings.

A strategic approach to mitigating the impacts of wild canids: proposed activities of the Invasive Animals Cooperative Research Centre

Wild canids (wild dogs and European red foxes) cause substantial losses to Australian livestock industries and environmental values. Both species are actively managed as pests to livestock production. Contemporaneously, the dingo proportion of the wild dog population, being considered native, is protected in areas designated for wildlife conservation. Wild dogs particularly affect sheep and goat production because of the behavioural responses of domestic sheep and goats to attack, and the flexible hunting tactics of wild dogs. Predation of calves, although less common, is now more economically important because of recent changes in commodity prices. Although sometimes affecting lambing and kidding rates, foxes cause fewer problems to livestock producers but have substantial impacts on environmental values, affecting the survival of small to medium-sized native fauna and affecting plant biodiversity by spreading weeds. Canid management in Australia relies heavily on the use of compound 1080-poisoned baits that can be applied aerially or by ground. Exclusion fencing, trapping, shooting, livestock-guarding animals and predator calling with shooting are also used. The new Invasive Animals Cooperative Research Centre has 40 partners representing private and public land managers, universities, and training, research and development organisations. One of the major objectives of the new IACRC is to apply a strategic approach in order to reduce the impacts of wild canids on agricultural and environmental values in Australia by 10%. In this paper, the impacts, ecology and management of wild canids in Australia are briefly reviewed and the first cooperative projects that will address IACRC objectives for improving wild dog management are outlined.

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.

In vitro culture of buffalo fly and infections with Wolbachia

"Develop and optimise reliable in vitro culture methods for buffalo fly "Use the in vitro system to determine whether experimental Wolbachia infection can be established in buffalo fly. "Prepare further applications for related work towards better control of buffalo fly, exploiting the in vitro culture system.

Fungal Biopesticide for cattle tick and buffalo fly control

Cattle ticks and buffalo flies impose significant economic burdens on the Northern Australian cattle and dairy industries. With the increased temperatures expected under climate change the range of parasites such as these is likely to extend. Current control options for these ectoparasites are limited by problems associated with chemical resistance and residues. Fungal biopesticides offer a sustainable and promising alternative method of control. Laboratory and animal studies have established the potential for the fungus Metarhizium in tick control and provided data that suggests a secondary effect of buffalo fly control is possible. Small field trials are required to obtain a proof of concept for the control of ticks and buffalo flies on animals.

Detection and differentiation of bovine herpesvirus 1 and 5 using a multiplex real-time polymerase chain reaction.

A multiplex real-time PCR was developed for the detection and differentiation of two closely related bovine herpesviruses 1 (BoHV-1) and 5 (BoHV-5). The multiplex real-time PCR combines a duplex real-time PCR that targets the DNA polymerase gene of BoHV-1 and BoHV-5 and a real-time PCR targeting mitochondrial DNA, as a house-keeping gene, described previously by Cawthraw et al. (2009). The assay correctly identified 22 BoHV-1 and six BoHV-5 isolates from the Biosecurity Sciences Laboratory virus collection. BoHV-1 and BoHV-5 were also correctly identified when incorporated in spiked semen and brain tissue samples. The detection limits of the duplex assay were 10 copies of BoHV-1 and 45 copies of BoHV-5. The multiplex real-time PCR had reaction efficiencies of 1.04 for BoHV-1 and 1.08 for BoHV-5. Standard curves relating Ct value to template copy number had correlation coefficients of 0.989 for BoHV-1 and 0.978 for BoHV-5. The assay specificity was demonstrated by testing bacterial and viral DNA from pathogens commonly isolated from bovine respiratory and reproductive tracts. The validated multiplex real-time PCR was used to detect and differentiate BoHV-1 and BoHV-5 in bovine clinical samples with known histories.

The first five days: field and laboratory investigations during the early stages of the equine influenza outbreak in Australia, 2007.

Until August 2007, Australia was one of only three countries internationally recognised to be free of equine influenza (EI). This report documents the diagnosis of the first cases of EI in Australian horses and summarises the investigations that took place over the next 5 days. During that time, a multifocal outbreak was identified across eastern New South Wales and south-eastern Queensland. The use of an influenza type A pan-reactive real-time reverse transcription polymerase chain reaction allowed rapid confirmation of suspect cases of EI.

Differentiation of Solenopsis invicta social forms using high resolution melt PCR.

Solenopsis invicta Buren (red imported fire ant) are invasive pests that have the capability of major destructive impacts on lifestyle, ecology and economy. Control of this species is dependent, in part, upon ability to estimate the potential spread from newly discovered nests. The potential for spread and the spread characteristics differ between monogyne and polygyne social forms. Prior to this study, differentiation of the two social forms in laboratory test samples commonly used a method involving restriction endonuclease digestion of an amplified Gp-9 fragment. Success of this assay is limited by the quality of DNA, which in the field-collected insects may be affected by temporary storage in unfavourable conditions. Here, we describe an alternative and highly objective assay based upon a high resolution melt technique following preamplification of a significantly shorter Gp-9 fragment than that required for restriction endonuclease digestion. We demonstrate the application of this assay to a S. invicta incursion in Queensland, Australia, using field samples from which DNA may be partially degraded. The reductions in hands-on requirements and overall duration of the assay underpin its suitability for high-throughput testing.

Multidrug-resistant extraintestinal pathogenic Escherichia coli of sequence type ST131 in animals and foods.

Multidrug-resistant Escherichia colt sequence type 131 (51131) has recently emerged as a globally distributed cause of extraintestinal infections in humans. Diverse factors have been investigated as explanations for ST131's rapid and successful dissemination, including transmission through animal contact and consumption of food, as suggested by the detection of ST131 in a number of nonhuman species. For example, ST131 has recently been identified as a cause of clinical infection in companion animals and poultry, and both host groups have been confirmed as faecal carriers of ST131. Moreover, a high degree of similarity has been shown among certain ST131 isolates from humans, companion animals, and poultry based on resistance characteristics and genomic background and human and companion animal ST131 isolates tend to exhibit similar virulence genotypes. However, most ST131 isolates from poultry appear to possess specific virulence genes that are typically absent from human and companion animal isolates, including genes associated with avian pathogenic E. coli. Since the number of reported animal and food-associated ST131 isolates is quite small, the role of nonhuman host species in the emergence, dissemination, and transmission of ST131 to humans remains unclear. Nevertheless, given the profound public health importance of the emergent ST131 clonal group, even the limited available evidence indicates a pressing need for further careful study of this significant question.

Effectiveness of Various Artificial Larval Diets for Rearing Bactrocera passiflorae (Froggatt) and B. xanthodes (Broun) in the Laboratory in Fiji

Laboratory colonies of Bactrocera passiflorae (Froggatt) and B. xanthodes (Broun) were established at Koronivia Research Station, Fiji in 1991. Laboratory rearing of the two economically important species was a prerequisite to studies conducted on protein bait spray and quarantine treatment development. To increase the production of laboratory reared fruit flies for this research and also to have a substitute larval diet available, replicated comparisons of the effectiveness of larval diets were carried out using B. passiflorae and B. xanthodes. The diets compared were pawpaw/bagasse, dehydrated carrot and diets used for culturing Mediterranean fruit fly (Ceratitis capitata Wiedemann), Oriental fruit fly (B. dorsalis Hendel), melon fly (B. cucurbitae Coquillett) and B. latifrons (Hendel), pawpaw diet and breadfruit diet. B. passiflorae and B. xanthodes eggs seeded onto the various diets were allowed to develop into larvae, pupae and adults. The percentage egg hatch, number of pupae recovered, percentage pupal mortality, weight of 100 pupae, number of adults and percentage eclosion were used to determine the effectiveness of the diets. Results showed that pawpaw/bagasse and dehydrated carrot diets performed favorably for both species. The pawpaw diet currently used as standard larval diets for both species is the most readily available and easiest to use. Breadfruit diet was tested on B. xanthodes only and showed that it was a suitable substitute for the pawpaw-based diets. Other larval diets, cassava/pawpaw and banana diets, that have been developed and used in the South Pacific areas are also discussed in this paper. When pawpaw or breadfruit are not available, dehydrated carrot diet may be substituted for fruit-based larval diets.

Laboratory-rearing Techniques for Tephritid Fruit Flies in the South Pacific

Laboratory colonies of 15 economically important species of multi-host fruit flies (Diptera:Tephritidae) have been established in eight South Pacific island countries for the purpose of undertaking biological studies, particularly host status testing and research on quarantine treatments. Laboratory rearing techniques are based on the development of artificial diets for larvae consisting predominately of the pulp of locally available fruits including pawpaw, breadfruit and banana. The pawpaw diet is the standard diet and is used in seven countries for rearing 11 species. Diet ingredients are standard proportions of fruit pulp, hydrolysed protein and a bacterial and fungal inhibitor. The diet is particularly suitable for post-harvest treatment studies when larvae of known age are required. Another major development in the laboratory rearing system is the use of pure strains of Enterobacteriaceae bacterial cultures as important adult-feeding supplements. These bacterial cultures are dissected out of the crop of wild females, isolated by sub-culturing, and identified before supply to adults on peptone yeast extract agar plates. Most species are egged using thin, plastic receptacles perforated with 1 mm oviposition holes, with fruit juice or larval diet smeared internally as an oviposition stimulant. Laboratory rearing techniques have been standardised for all of the Pacific countries. Quality control monitoring is based on acceptable ranges in per cent egg hatch, pupal weight and pupal mortality. Colonies are rejuvenated every 6 to 12 months by crossing wild males with laboratory-reared females and vice versa. The standard rearing techniques, equipment and ingredients used in collecting, establishment, maintenance and quality control of these fruit fly species are detailed in this paper.

Bentonite can decrease ammonia volatilisation losses from poultry litter: laboratory studies

Ammonia volatilisation from manure materials within poultry sheds can adversely affect production, and also represents a loss of fertiliser value from the spent litter. This study sought to compare the ability of alum and bentonite to decrease volatilisation losses of ammonia from spent poultry litter. An in-vessel volatilisation trial with air flushing, ammonia collection, and ammonia analysis was conducted over 64 days to evaluate the mitigation potential of these two materials. Water-saturated spent litter was incubated at 25°C in untreated condition (control) or with three treatments: an industry-accepted rate of alum [4% Al2(SO4)3·18H2O by dry mass of litter dry mass; ALUM], air-dry bentonite (127% by dry mass; BENT), or water-saturated bentonite (once again at 127% by dry mass; SATBENT). A high proportion of the nitrogen contained in the untreated spent litter was volatilised (62%). Bentonite additions were superior to alum additions at retaining spent litter ammonia (nitrogen losses: 15%, SATBENT; 34%, BENT; 54%, ALUM). Where production considerations favour comparable high rates of bentonite addition (e.g. where the litter is to be re-formulated as a fertiliser), this clay has potential to decrease ammonia volatilisation either in-shed or in spent litter stockpiles or formulated products, without the associated detrimental effect of alum on phosphorus availability.