Experimental acute yellow-wood (Terminalia oblongata) intoxication in sheep

SUMMARY An aqueous suspension of air-dried, hammer-milled leaf of Terminalla oblongata (yellow-wood) was administered to sheep by gavage, as a single dose of 5 to 20 g (dry weight)/kg body weight. Doses of 15 g/kg, or more, caused depression, Inappetence, abdominal pain and reduced ruminal movements within 24 to 48 h and some sheep also showed dyspnoea, oplsthotonus and champing of the Jaws. Haematology and blood gas and acid-base measurements were unaffected. In sheep given a dose of 12.5 g/kg, or more, plasma osmolality, aspartate aminotransferase activity and potassium and bilirubin concentrations Increased while plasma total protein markedly decreased and plasma sodium concentration and alkaline phosphatase activity remained normal. Most sheep were necropsled 48 h after dosing. The liver showed zonal hepatocellular necrosis, the pattern of which varied with the dose given. No renal lesions were observed, although one sheep given a very high dose became azotaemic and hyperkalaemic. Hydrothorax, hydroperlcardlum and ascltes developed In sheep given doses of 15 or 20 g/kg.     

Biological and sequence comparisons of Potato virus Y isolates associated with potato tuber necrotic ringspot disease

The biological and molecular relationships between a large number of Potato virus Y (PVY) isolates were examined, concentrating mainly on isolates associated with potato tuber necrotic ringspot disease (PTNRD). Following detailed analysis of the coat-protein gene, four main groups were identified which broadly corresponded to the phenotype of the different isolates. The groups comprised the ordinary strain (PVY^O), the necrotic strain (PVY^N), the C strain (PVY^C) and a group of recombinant (between ordinary and necrotic) isolates. In the latter group, all members were associated with PTNRD. However, four nonrecombinant isolates were also identified which were associated with PTNRD or tuber necrosis. Three were from tubers showing PTNRD symptoms in the field, while the fourth originated from symptomless tubers, but could cause necrotic rings on tubers under glasshouse conditions. The results show that although coat-protein recombination is always found associated with the PTNRD phenotype, some nonrecombinant isolates have very similar biological properties.     

16alpha-Bromo-epiandrosterone therapy modulates experimental feline immunodeficiency virus viremia: initial enhancement leading to long-term suppression

16alpha-Bromo-epiandrosterone (epiBr), a synthetic derivative of the natural hormone dehyroepiandrosterone (DHEA), was evaluated for its effects on feline immunodeficiency virus (FIV) infection in experimental cats. The rationale for this study was based on the ability of DHEA to significantly reduce the mortality to viral infections in mice. DHEA and epiBr also have demonstrable in vitro anti-viral activity for both HIV-1 and FIV. Preliminary pharmacokinetic studies in cats demonstrated that subcutaneously injected epiBr was rapidly absorbed, completely metabolized, and nontoxic. Metabolites were excreted in both urine and feces, with the latter having the most complex pattern of breakdown products. Cats were then divided into four groups; two groups were infected with FIV and two uninfected. Two groups, one infected and one uninfected were treated on 5 consecutive days of weeks 0, 4, 8, 12 and 16 with epiBr. The remaining two groups were mock treated with the drug vehicle alone. Treatment started 1 week prior to infection and extended for 4 weeks after infection. Cats were observed for 20 weeks post-FIV infection. Infected cats had identical decreases in blood neutrophil and lymphocyte counts following, regardless of whether they were treated with epiBr or vehicle alone. The CD4/CD8 T-cell ratio was decreased following FIV exposure, but was significantly more decreased for the epiBr treated animals from week 2 post-infection onward. CD4+ T cells were decreased in FIV-infected cats treated with epiBr compared to their untreated cohort, while CD8+ T cells tended to be higher in treated animals. FIV infected cats that were treated with epiBr had over one-log higher virus loads at week 2 post-infection than non-epiBr treated cohorts. In spite of this enhanced initial viremia, the subsequent levels of virus in the blood were significantly lower in epiBr treated versus untreated animals. EpiBr treated cats had significantly higher FIV-p24 antibody responses than control cats receiving vehicle alone, although primary and secondary antibody responses to a T-cell dependent non-FIV antigen, keyhole limpet hemocyanin (KLH), were unaffected. EpiBr treatment significantly decreased the expected FIV-induced suppression of IL-12 p40 mRNA levels in peripheral blood mononuclear cells (PBMCs) observed at weeks 4, 5, 8, 9 and 16 post-infection, but had no influence on FIV-induced changes in IL-4, IL-6, IL-10, IFN-gamma, MIP-1alpha and RANTES.     

Immunohistochemical Expression of Growth Factors in the Follicular Wall of Normal and Cystic Ovaries of Sows

The expression of growth factors was evaluated immunohistochemically in normal and cystic ovaries of sows. The immunohistochemically stained area (IHCSA) was quantified by image analysis to analyse the expression of these proteins in the follicular wall of secondary, tertiary and cystic follicles. IGF‐I immunoreactivity was strong in the granulosa cell layer (GC), moderate in the theca interna (TI) and mild in the theca externa (TE) of the normal follicles. There was severe reduction of the labelling to IGF‐I in the GC of the follicular and luteinized cysts. In the normal follicles, the reactivity for IGF‐II was very similar to pattern noted in IGF‐I. There was reduction of the IHCSAs in the GC of the follicular and luteinized cysts, but the decrease was not significant. The staining of the IGF‐II in the TI and TE of the cysts was increased, in comparison with normal follicles. The IHCSAs for VEGF were higher in the GC and TE of the normal follicles in contrast to TI, but this difference was noted only in the tertiary follicle. The VEGF reactivity increased in the GC of the cysts, in relation to normal follicles. The results of the current study show that the formation of ovarian cysts in sows is associated with alterations in the immunohistochemical expression of some growth factors.     

Relationships between Stocking and Anglers' Catches in Draycote Water Trout Fishery

The trout fishery at Draycote Water was investigated during the 1980 fishing season. Fish stocked were batch-marked according to the date of introduction by freeze branding, and catch data were obtained by the cooperation of anglers. Population estimates were made at the end of the fishing season using gill nets and mark-recapture techniques. Of the 32,960 marked brown and rainbow trout stocked, 69.8% were caught and declared by anglers. Returns of rainbow trout were better (78.1%) than those of brown trout (44.2%). Over 90% of all fish caught were taken within 45 days of stocking. Catch per unit effort fluctuated widely but was closely associated with stockings of fish. Catchability (Q) of stocked fish was found to diminish rapidly with time after stocking. At the end of the fishing season the estimated population of marked trout was 4045 (2 × SE = 250), compared with a theoretical number (stock less total catch) of 10,802, giving a mean daily apparent natural mortality, made up of the true natural mortality plus the undeclared catch, of 1.36%.     

Changes in productivity and profitability of wool-growing farms that follow recommendations from agricultural and veterinary studies

Objective To estimate the changes in productivity and profitability in a group of wool-growing farms as they adopted major recommendations from agricultural and veterinary studies.
Farms Four wool-growing farms in south western Victoria were selected from the clients of the Mackinnon Project, a farm consultancy service run from the University of Melbourne. Each farm had closely followed recommended procedures, kept comprehensive financial and physical records and had been clients for at least 5 years. The comparison group was the South Western Victoria Monitor Farm Project (SWVMFP), about 45 farms in the same region as the study farms that were monitored annually by Agriculture Victoria.
Procedure For a 7-year period, the financial and physical performance of both groups of farms was estimated. Stocking rate, wool production, gross farm income, farm operating costs, net farm income and return on assets were compared.
Results Mean gross farm income of the four study farms steadily rose from 86% of the average SWVMFP farm before the adoption of recommendations to an average of 155%. During the same period, net farm income rose from 70% to 207% of the average of the SWVMFP. Return on asset of the four farms rose irregularly from 26% to 145% of the average of the SWVMFP. Farm operating costs on the four farms were higher than for the SWVMFP group, but the ratio of costs remained relatively constant.
Conclusion The adoption of proven research results was associated with large increases in net farm income. An increase in gross income, rather than a reduction in costs was the main reason for this. Research results offer a way to increase the financial viability of wool-growing farmers, many of whom are currently unable to maintain their lifestyle, resources and infrastructure.     

Stand structure, fuel loads, and fire behavior in riparian and upland forests, Sierra Nevada Mountains, USA; a comparison of current and reconstructed conditions

Fire plays an important role in shaping many Sierran coniferous forests, but longer fire return intervals and reductions in area burned have altered forest conditions. Productive, mesic riparian forests can accumulate high stem densities and fuel loads, making them susceptible to high-severity fire. Fuels treatments applied to upland forests, however, are often excluded from riparian areas due to concerns about degrading streamside and aquatic habitat and water quality. Objectives of this study were to compare stand structure, fuel loads, and potential fire behavior between adjacent riparian and upland forests under current and reconstructed active-fire regime conditions. Current fuel loads, tree diameters, heights, and height to live crown were measured in 36 paired riparian and upland plots. Historic estimates of these metrics were reconstructed using equations derived from fuel accumulation rates, current tree data, and increment cores. Fire behavior variables were modeled using Forest Vegetation Simulator Fire/Fuels Extension.Riparian forests were significantly more fire prone under current than reconstructed conditions, with greater basal area (BA) (means are 87 vs. 29 m²/ha), stand density (635 vs. 208 stems/ha), snag volume (37 vs. 2 m³/ha), duff loads (69 vs. 3 Mg/ha), total fuel loads (93 vs. 28 Mg/ha), canopy bulk density (CBD) (0.12 vs. 0.04 kg/m³), surface flame length (0.6 vs. 0.4 m), crown flame length (0.9 vs. 0.4 m), probability of torching (0.45 vs. 0.03), predicted mortality (31% vs. 17% BA), and lower torching (20 vs. 176 km/h) and crowning indices (28 vs. 62 km/h). Upland forests were also significantly more fire prone under current than reconstructed conditions, yet changes in fuels and potential fire behavior were not as large. Under current conditions, riparian forests were significantly more fire prone than upland forests, with greater stand density (635 vs. 401 stems/ha), probability of torching (0.45 vs. 0.22), predicted mortality (31% vs. 16% BA), and lower quadratic mean diameter (46 vs. 55 cm), canopy base height (6.7 vs. 9.4 m), and frequency of fire tolerant species (13% vs. 36% BA). Reconstructed riparian and upland forests were not significantly different. Our reconstruction results suggest that historic fuels and forest structure may not have differed significantly between many riparian and upland forests, consistent with earlier research suggesting similar historic fire return intervals. Under current conditions, however, modeled severity is much greater in riparian forests, suggesting forest habitat and ecosystem function may be more severely impacted by wildfire than in upland forests.