A producer survey of knowledge and practises on gastrointestinal nematode control within the Australian goat industry.

Gastrointestinal nematodes (GINs) have been identified in Australia as a major problem in goat production, with few anthelmintics registered for use in goats. Therefore, anecdotally many producers use anthelmintics that have not been registered for goats. Using unregistered products could increase selection pressure for anthelmintic resistance as well as safety and/or meat or milk chemical residues of products from treated goats. This producer survey was conducted in 2014 to establish Australian goat producer knowledge, perception and practises of GIN treatment and control. Eighty-eight producers responded to the survey. Of these respondents, 90% thought that GINs were a problem for the Australian goat industry, and 73% considered GINs had caused production losses or health impacts for their goats during the 5 years prior to the survey. With regard to anthelmintic resistance, 7% believed that anthelmintic resistance was not a problem at all, 93% acknowledged anthelmintic resistance was a problem in Australian goats herds, with 25% of these reporting their properties as being affected. The majority (81%) of respondents believed the number of anthelmintics registered for goats was inadequate for effective GIN control. Of the 85% of producers who used an anthelmintic during the survey period, 69% had used a treatment not registered for use in goats. Fifty respondents listed the anthelmintic dosage used, and 50% of those had used a dose rate greater than the recommended label dose. The average frequency of administration of anthelmintic was 2.5 times per annum. Of the 51% of respondents who listed the frequency of their treatments given during the survey period, 16% administered four or more treatments annually to the majority of their goats and 8% administered treatments on an "as needed" basis. Faecal egg count (FEC) had been performed on 72% of properties in at least one of the six years covered by the survey. These results indicated that the majority of surveyed producers use anthelmintics that are not registered for use in goats and at different dose rates to label. These practises have the potential for increasing the spread of anthelmintic resistance in the GIN populations of goats and sheep. Further, giving dose rates in excess of label recommendations could impact goat safety and/or product residues. Further research is needed to investigate these risks and evaluate more sustainable GIN control options for goat herds. In addition more effective dissemination of information is necessary for the improvement of the Australian goat industry.

Evidence for high genetic diversity of NAD1 and COX1 mitochondrial haplotypes among triclabendazole resistant and susceptible populations and field isolates of Fasciola hepatica (liver fluke) in Australia.

In recent years, the global incidence of Fasciola hepatica (liver fluke) infections exhibiting resistance to triclabendazole (TCBZ) has increased, resulting in increased economic losses for livestock producers and threatening future control. The development of TCBZ resistance and the worldwide discovery of F. hepatica population diversity has emphasized the need to further understand the genetic structure of drug susceptible and resistant Fasciola populations within Australia. In this study, the genetic diversity of liver flukes was estimated by sequencing mitochondrial DNA (mtDNA) encoding the NAD1 (530 bp) and COX1 (420 bp) genes of 208 liver flukes (F. hepatica) collected from three populations: field isolates obtained from abattoirs from New South Wales (NSW) and Victoria (Vic); three TCBZ-resistant fluke populations from NSW and Victoria; and the well-established TCBZ-susceptible Sunny Corner laboratory isolate. Overall nucleotide diversity for all flukes analysed of 0.00516 and 0.00336 was estimated for the NAD1 and COX1 genes respectively. Eighteen distinct haplotypes were established for the NAD1 gene and six haplotypes for the COX1 gene, resulting in haplotype diversity levels of 0.832 and 0.482, respectively. One field isolate showed a similar low level of haplotype diversity as seen in the Sunny Corner laboratory isolate. Analysis of TCBZ-resistant infrapopulations from 3 individual cattle grazing one property revealed considerable sequence parasite diversity between cattle. Analysis of parasite TCBZ-resistant infrapopulations from sheep and cattle revealed haplotypes unique to each host, but no significant difference between parasite populations. Fst analysis of fluke populations revealed little differentiation between the resistant and field populations. This study has revealed a high level of diversity in field and drug resistant flukes in South-Eastern Australia.

Comparative kinetics of serological and coproantigen ELISA and faecal egg count in cattle experimentally infected with Fasciola hepatica and following treatment with triclabendazole.

Three methods of diagnosing Fasciola hepatica (F. hepatica) infection (a coproantigen ELISA, Bio-X Diagnostics, Belgium, Faecal Egg Count (FEC), and a serum IgG ELISA,Bio-X Diagnostics, Belgium) were evaluated in artificially infected cattle, with and without drug treatment. Specifically, the potential value of the coproantigen ELISA in the quantitation of F. hepatica infection was sought. Twelve steers were each infected with 100, 200 or 500 metacercariae (n=4 cattle/group). On day 84, post infection (PI), 2 animals from each group were treated orally with triclabendazole (TCBZ). Faecal and blood samples were collected weekly after infection from all animals, as well as over 5 consecutive days (days 105-109 PI) for the six animals remaining infected to determine the repeatability of these assays. Cattle were killed 126 days PI and the coproantigen, FEC and IgG levels were compared with the number of fluke recovered. Animals first tested positive for infection with the serum ELISA, with 11/12 animals positive on day 28, and IgG responses increased to day 42 PI. The coproantigen ELISA was first positive on day 42 (3/12 animals), with all animals positive by day 56 PI. The first F. hepatica egg was detected on day 49 from an animal infected with 500 metacercariae; however only on one occasion (day 84) did all animals return positive FEC. Within one week of treatment with TCBZ, all six treated animals had returned to negative status by coproantigen ELISA and FEC whereas IgG levels persisted. Weekly variation in both coproantigen level and FEC was evident throughout the trial. Results from the consecutive daily collections varied greatly between days for both methods, with 2-6-fold differences in coproantigen levels and 2-4-fold variation in FEC. Strong correlations were observed between fluke burdens (day 126) and day 125 coproantigen levels (R(2)=0.8718) and FEC (R(2)=0.8368). The coproantigen ELISA was more sensitive than FEC (FEC displayed false negatives) and detected infection earlier. This ELISA showed good correlation to fluke burdens in these cattle and has promise as a test for detecting low fluke burdens.

Effects of a commercial dose of L-tryptophan on plasma tryptophan concentrations and behaviour in horses.

REASON FOR PERFORMING STUDY: L-tryptophan is a common ingredient in equine calmative products, but its effectiveness has not been demonstrated in horses. HYPOTHESIS: To determine whether a commercial dose of L-tryptophan increases plasma tryptophan and alters behaviour in horses fed a roughage or concentrate meal. METHODS: L-tryptophan (6.3 g) or placebo (water) was administered per os in a cross-over design, to 12 Thoroughbred horses (503 +/- 12.1 kg bwt), just before a meal of lucerne hay or oats. Plasma tryptophan was measured by gas chromatography. Horse behaviour was observed in an empty enclosure, then in the presence of an unfamiliar person and a novel object. RESULTS: Total plasma tryptophan increased 3-fold in both studies, peaking 1.5-2 h after dosing. After the peak, tryptophan remained high for several hours if the horses had been fed hay, but fell sharply if fed oats, consistent with the glycaemic responses to these meals. However, the ratio of tryptophan to 4 large neutral amino acids (phenylalanine, tyrosine, leucine and isoleucine) increased in the tryptophan-treated horses to a similar extent and for a similar duration, with both diets. The presence of a stranger or novel object increased heart rate (P<0.05), but caused no behavioural effects that were altered by tryptophan, regardless of the diet. CONCLUSIONS: Plasma tryptophan increases when tryptophan is administered at a dose used in some commercial products, but this is not reflected by marked behavioural changes in the horse. POTENTIAL RELEVANCE: Further work is required to refine behavioural tests and identify an effective dose of L-tryptophan in the horse.