Blindness in goats following ingestion of Stypandra glauca

Twenty-seven of 427 Angora goats of mixed age became blind within a week of consuming large amounts of Stypandra glauca ("nodding blue lily"). A further 200 goats were depressed for several weeks, but most subsequently recovered. Blindness was associated with optic nerve neuropathy which is postulated to have followed compression of the optic nerves within the bony optic canals as a result of severe myelin oedema. Histologically, the intracanalicular portion of the optic nerve was sclerotic, while the intracranial portion of the optic nerve and the optic tracts were degenerating. The retrobulbar portion of the optic nerve was relatively unaffected. In addition, multifocal retinal photoreceptor degeneration was found ophthalmoscopically and histologically. The syndrome was not reproduced during a trial in which 2 goats were fed 4 and 20 kg of S. glauca harvested after it had finished flowering, more than 3 weeks after the first natural cases of blindness. Based on epidemiological and pathological data we propose that S. glauca is toxic to stock, but only for a short period while flowering in spring.     

Effects of two large doses of equine recombinant growth hormone on clinical, haematological and serum biochemical variables in adult horses

Objective To evaluate the clinical, haematological, and serum biochemical effects of two large doses of recombinant equine growth hormone.
Design Duplicated Latin square.
Sample population
Three Thoroughbred and three Standardbred mares aged between 12 and 17 years.
Procedure Two horses were randomly assigned into one of three groups. On each of three successive days, each horse pair received one of two dosages of growth hormone or a saline placebo so that by the end of the experiment all three horse pairs had received both dosages and the saline placebo. Dose rates selected were 50 μg/kg, and 100 μg/kg. A clinical examination was performed and a venous blood sample drawn for a complete blood count and serum biochemical analysis before administration of growth hormone and at 1, 2, 3, 4, 6, 8 and 24 h after injection. Data were analysed by a repeated measures analysis of variance assessing the effects of dose and time.
Results There was an effect of time on a number of clinical, haematological, and serum biochemical variables. There were significant effects of growth hormone on heart rate and serum glucose concentration but values for both variables remained within the reference range.
Conclusion The results of the present study suggest that equine recombinant growth hormone has a wide margin of safety and show that the single administration of up to five times the recommended dose rate has no significant effects on clinical, haematological, or serum biochemical variables.     

Comparison of a competitive inhibition ELISA and the card agglutination test for detection of antibodies to Anaplasma marginale and Anaplasma centrale in cattle

OBJECTIVE: To compare a recently developed recombinant MSP-5 competitive inhibition ELISA with a card agglutination test for detection of antibodies to Anaplasma marginale and Anaplasma centrale in Australian cattle. MATERIALS AND METHODS: The ELISA was compared with the card agglutination test using 208 sera from cattle in Anaplasma-free herds, 86 sera from cattle experimentally infected with A marginale or A centrale and 757 sera from cattle in areas endemic for A marginale. RESULTS: The specificity of the ELISA, based on testing 208 sera from cattle in Anaplasma-free areas, was 99.5%, and the sensitivities for detection of antibodies to A marginale and A centrale in sera from the experimentally infected cattle were 98.0% and 100%, respectively. For the same sets of sera, the specificity of the card agglutination test was 98.6% and the sensitivities for detection of antibodies to A marginale and A centrale were 98.0% and 100%, respectively. For the 757 sera collected from cattle in areas endemic for A marginale, the agreement between the ELISA and the card agglutination test depended on the positive threshold selected for the ELISA. The maximum achievable agreement was 91.5% (kappa = 0.73; 95% confidence interval 0.66, 0.79). CONCLUSION: We conclude that the competitive inhibition ELISA is a useful alternative to the card agglutination test for detection of A marginale or A centrale infection in cattle. The assay should be particularly useful for epidemiological applications such as prevalence studies and control programs.     

Epidemic of blindness in kangaroos - evidence of a viral aetiology

OBJECTIVE: To determine the cause of an epidemic of blindness in kangaroos. DESIGN AND PROCEDURES: Laboratory examinations were made of eyes and brains of a large number of kangaroos using serological, virological, histopathological, electron microscopical, immunohistochemical methods, and PCR with cDNA sequencing. In addition, potential insect viral vectors identified during the disease outbreak were examined for specific viral genomic sequences. SAMPLE POPULATION: For histopathological analysis, 55 apparently blind and 18 apparently normal wild kangaroos and wallabies were obtained from New South Wales, Victoria, South Australia, and Western Australia. A total of 437 wild kangaroos and wallabies (including 23 animals with apparent blindness) were examined serologically. RESULTS: Orbiviruses of the Wallal and Warrego serogroups were isolated from kangaroos affected with blindness in a major epidemic in south-eastern Australia in 1994 and 1995 and extending to Western Australia in 1995/96. Histopathological examinations showed severe degeneration and inflammation in the eyes, and mild inflammation in the brains. In affected retinas, Wallal virus antigen was detected by immunohistochemical analysis and orbiviruses were seen in electron microscopy. There was serological variation in the newly isolated Wallal virus from archival Wallal virus that had been isolated in northern Australia. There were also variations of up to 20% in genotype sequence from the reference archival virus. Polymerase chain reactions showed that Wallal virus was present during the epidemic in three species of midges, Culicoides austropalpalis, C dycei and C marksi. Wallal virus nucleic acid was also detected by PCR in a paraffin-embedded retina taken from a blind kangaroo in 1975. CONCLUSION: Wallal virus and perhaps also Warrego virus are the cause of the outbreak of blindness in kangaroos. Other viruses may also be involved, but the evidence in this paper indicates a variant of Wallal virus, an orbivirus transmitted by midges, has the strongest aetiological association, and immunohistochemical analysis implicates it as the most damaging factor in the affected eyes.     

Effects of dietary starches and the protein to energy ratio on growth and feed efficiency of juvenile cobia,Rachycentron canadum

Optimization of the protein to energy ratio in juvenile cobia (Rachycentron canadum) would allow the production of diets that maximize growth without the addition of excess energy that may increase costs or even be detrimental to the health of the fish. During a 6‐week growth trial, juvenile cobia (5.6 ± 0.5 g fish^?1 initial weight) were fed five isonitrogenous and isolipidic diets containing various protein to energy ratios using starch as the energy source. At the end of the trial, some fish were analysed for body composition characteristics while the rest were used to examine the excretion of dietary starch in the feces. Survival and growth were not significantly affected, but feed efficiency (ranging from 0.64 to 0.94) and daily consumption (ranging from 45.3 to 64.1 g kg^?1 of body weight d^?1) were affected. No reduction in consumption due to excess energy was noted. Analysis of the fecal carbohydrate data showed a linear relationship between dietary inclusion and excretion of carbohydrates with no sign of reaching saturation. Results of this study suggest that cobia can utilize dietary carbohydrates up to at least 340 g kg^?1 of dry diet with an optimal protein to energy ratio of approximately 34 mg protein kJ^?1metabolizable energy.     

The response of oilseed rape (Brassica napus ssp. oleifera) accessions with different glucosinolate and erucic acid contents to four isolates of Peronospora parasitica (downy mildew) and the identification of new sources of resistance

A total of 101 Brassica napus ssp. oleifera accessions with seed differing in glucosinolate and erucic acid contents were screened for resistance to four isolates of Peronospora parasitica at the cotyledon stage. Two groups of accessions with different resistance factors were identified. Lines that were homogeneous for resistance were selected from seedling populations of accessions that exhibited a heterogeneous reaction to some isolates. The resistance of one group differs from that of cv, Cresor, the only oilseed rape cultivar reported to have an isolate-specific gene for resistance to P. parasitica. The isolate specificity of the second group was identical to that of cv, Cresor, A comparison of the response of host accessions which expressed moderate to full susceptibility at the cotyledon stage, with no clear differential response to any of the four P. parasitica isolates, indicated that those with high glucosinolate and high erucic acid contents (12 accessions) were slightly but significantly less susceptible than those with high glucosinolate and low erucic acid (19 accessions), or low glucosinolate and low erucic acid contents (28 accessions). The mean differences between accessions with low erucic acid but differing in glucosinolate content were inconsistent. The last result was further confirmed by investigating the expression of resistance to three isolates of P. parasitica at three different seedling growth stages among 11 accessions of oilseed rape with seeds low in erucic acid but differing in glucosinolate content.