Ergovaline does not alter the severity of ryegrass staggers induced by lolitrem B

AIM: To investigate a possible interaction between lolitrem B and ergovaline by comparing the incidence and severity of ryegrass staggers in sheep grazing ryegrass (Lolium perenne) containing lolitrem B or ryegrass containing both lolitrem B and ergovaline.

METHODS: Ninety lambs, aged approximately 6 months, were grazed on plots of perennial ryegrass infected with either AR98 endophyte (containing lolitrem B), standard endophyte (containing lolitrem B and ergovaline) or no endophyte, for up to 42 days from 2 February 2010. Ten lambs were grazed on three replicate plots per cultivar. Herbage samples were collected for alkaloid analysis and lambs were scored for ryegrass staggers (scores from 0–5) weekly during the study. Any animal which was scored ≥4 was removed from the study.

RESULTS: Concentrations of lolitrem B did not differ between AR98 and standard endophyte-infected pastures during the study period (p=0.26), and ergovaline was present only in standard endophyte pastures. Ryegrass staggers was observed in sheep grazing both the AR98 and standard endophyte plots, with median scores increasing in the third week of the study. Prior to the end of the 42-day grazing period, 22 and 17 animals were removed from the standard endophyte and AR98 plots, respectively, because their staggers scores were ≥4. The cumulative probability of lambs having scores ≥4 did not differ between animals grazing the two pasture types (p=0.41).

CONCLUSIONS AND CLINICAL RELEVANCE: There was no evidence for ergovaline increasing the severity of ryegrass staggers induced by lolitrem B. In situations where the severity of ryegrass staggers appears to be greater than that predicted on the basis of concentrations of lolitrem B, the presence of other tremorgenic alkaloids should be investigated.     

Assessing landscapes: a case study of tree and shrub diversity in the seasonally dry tropical forests of Oaxaca, Mexico and southern Honduras

Tropical dry forests, with their distinct and economically important diversity, are acknowledged conservation priorities because of alarming rates of forest conversion. Whilst it is realised that terrestrial conservation requires an understanding of landscape level patterns of diversity, forests are rarely assessed accordingly. Here we demonstrate that, in the case of the seasonally dry tropical forests of the Pacific watershed of Mesoamerica, landscape level assessment of woody diversity can inform decision making relevant to both between-landscape and within-landscape prioritisation. We report floristic surveys of dry forest landscapes in Oaxaca, Mexico and southern Honduras. It is noted that these forests are floristically similar to other seasonally dry tropical forests in the neotropics. By calculation of Genetic Heat Indices, a relative measure of the concentration of restricted range species in a sample, we determine that the conservation of the tree diversity of the coastal lowlands of Oaxaca should be prioritised over that of southern Honduras. The current conservation status of forested areas in Oaxaca is briefly described. We suggest that the greater degree of anthropogenic disturbance in southern Honduras may explain the relative lack of restricted range species there. We argue that some forest fallows can act as analogues of mature forest and therefore landscape elements other than mature forest need to be included in forest conservation assessments. We conclude that diversity sampling of any forest type should not be limited to mature forests, but extended to other elements of forested landscapes.     

Akabane disease in sheep

Perinatal lamb mortality, associated with malformations of the CNS due to Akabane viral infection, occurred in 4 of 9 flocks of ewes lambing on 3 farms between 26 May and 14 November, 1976. Cases were restricted to ewes conceiving prior to the second week of March and lambing between 26 May and 19 July. As judged by seroconversion in sentinel flocks on 2 of the farms, field infection with Akabane virus occurred mainly between mid-February and mid-April. Malformations of the CNS occurred in 42.5%, 51.2%, 100% and 31.0% of the dead lambs examined in the affected flocks respectively. Prevalence in the 4 affected flocks, expressed as the proportion of ewes lambing which delivered at least one malformed foetus, was 6.1%, 8.4%, 88.9% and 5.7% respectively. Lamb mortality due to malformations of the CNS was 7.1%, 5.5%, 92.3% and 5.7% of lambs born. Age-specific prevalence was calculated for 3 of the 4 flocks and 2-year-old ewes accounted for 71.4% and 76.9% of total cases respectively in 2 flocks, whereas in one flock malformations occurred at equivalent frequencies throughout several older age groups. Birthweights of affected lambs were usually significantly lighter than those of unaffected lambs of similar sex and birth-type, and their mean duration of gestation was slightly, and significantly, prolonged. Micrencephaly (88.1% of cases) and hydrocephalus (68.7% of cases) were the outstanding pathological features of the malformations with hydranencephaly, microgyria, porencephaly and attenuation of the spinal cord occurring at much lower frequencies.(ABSTRACT TRUNCATED AT 250 WORDS)     

The occurrence of congenital heart defects in an inbred herd of pigs in Australia

OBJECTIVE: To report on the first case of congenital heart defects in pigs in Australia. DESIGN: Retrospective analysis of case records from an inbred herd of "Westran" pigs at the University of Sydney, between January 2001 and December 2004. Detailed gross and histological examination of 15 hearts from pigs that had died or were euthanased in 2004. CASE DETAILS: The necropsy records from a population of 471 pigs that had died (106 pigs) or were euthanased for research purposes (365 pigs) were analysed and the incidence of heart defects recorded, together with basic demographic data. No attempts were made to diagnose the condition in live pigs. RESULTS: Congenital heart defects were diagnosed in 6.4% of pigs but this is likely to be an underestimate of the incidence of the deformity. Eighteen pigs died on the farm as a result of the defect, and 12 pigs were diagnosed with the defect as an incidental finding. The most common abnormality seen at necropsy was a sac-like dilatation on the right lateral surface of the right atrium. This was associated with secondary deformity and hypoplasia of the adjacent left ventricle, interventricular region and part of the right ventricle. All hearts showed atrial septal defects of varying size. CONCLUSION: This is the first reported case of congenital heart defects in pigs in Australia, and one of less than five reported cases of atrial septal defects in pigs in the world. The authors conclude that there may be an element of genetic predisposition to the malformation, since it has only been reported in this inbred line of pigs.