PRE-HARVEST DESICCATION OF HERBAGE SEED CROPS AND ITS EFFECT ON SEED QUALITY

Seed crops of perennial ryegrass S321 and tetraploid hybrid ryegrass Sabrina were sprayed with 3 pt diquat in 30 gal. water/ac (4.21 diquat in 337 1 water/ha) a few days before the normal date for harvest. Very low germination values were obtained wben the harvested seed was later tested and the production of abnormal seedlings from the treated crops was attributed to the presence of diquat in the seed. On the basis of these results the use of diquat is not recommended as a pre-harvest desiccant for ryegrass seed crops.     

A long-term study of knowledge,risk, and ethics for students enrolled in an introductory biotechnology course

Since 1989, an undergraduate course addressing issues concerning biotechnology in agriculture has been taught annually. To determine the extent to which students were engaged in classroom instruction and assimilated knowledge from the course, students were asked to complete an "Attitudes About Biotechnology" questionnaire. Students were queried about their knowledge of biotechnology, perceptions of risks associated with biotechnology, and ethics and attitudes toward the use of biotechnology in agriculture. Responses to the survey questions were evaluated both pre-and postcourse. Data were collected from 13 classes over a 10-yr period. Inspection of the precourse grade point average and the course grades for these students revealed no trends up or down over the period of this study. Similarly, inspection of the data revealed no effect from problem-based learning, student-facilitated group work, or technology on student attainment of knowledge, perception of risk, or ethical views. For each of the five knowledge questions, the average score increased as a result of taking the course. On two of the knowledge questions, the average score increase for females from pre- to postcourse was greater than for males. Based on our measurements using the postcourse questionnaire, the correlation between perceived and actual knowledge was not significantly different from zero. In two of the four risk questions, there was no change in average score as a result of the course; however, student perception of risk associated with genetic engineering of plants increased. Although average scores for student perception of risk due to the perceived impact of genetically engineered products on people or the environment decreased from pre- to postcourse assessment, the average score was higher (P < 0.01) for females than for males. Males were more accepting of genetic manipulation of cells in a laboratory than were females both pre- and postcourse. Although student knowledge of biotechnology was increased and the perceived risk due to biotechnology was altered, there was no evidence that students altered their ethical position on biotechnology as a result of this course.     

Quantitative risk assessment of human listeriosis from consumption of soft cheese made from raw milk

Microbial hazards have been identified in soft cheese made from raw milk. Quantification of the resulting risk for public health was attempted within the frame of the Codex Alimentarius Commission, 1995 approach to quantitative risk assessment, using Monte Carlo simulation software. Quantitative data could only be found for Listeria monocytogenes. The complete process of cheese making was modeled, from milking to consumption. Using data published on the different sources of milk contamination (environment and mastitis) and bacterial growth, distributions were assumed for parameters of the model. Equations of Farber, J.M., Ross, W.H., Harwing, J. (1996) for general and at-risk populations were used to link the ingested dose of L. monocytogenes to the occurrence of listeriosis. The probability of milk contamination was estimated to be 67% with concentration ranging from 0 to 33 CFU ml⁻¹. The percentage of cheese with a predicted concentration of L. monocytogenes greater than 100 CFU g⁻¹ was low (1.4%). The probability of consuming a contaminated cheese serving was 65.3%. Individual annual cumulative risk of listeriosis, in a population each consuming 50 servings of 31 g, ranged from 1.97 × 10⁻⁹ to 6.4 × 10⁻⁸ in a low-risk sub-population and 1.04 10⁻⁶ to 7.19 10⁻⁵ in a high-risk sub-population. The average number of expected cases of listeriosis per year was 57 for a high-risk sub-population and one for a low-risk healthy sub-population. When the frequency of environmental milk contamination was reduced in the model and L. monocytogenes mastitis was eliminated, the expected incidence of listeriosis decreased substantially; the average number of expected cases was reduced by a factor of 5. Thus the usefulness of simulation to demonstrate the efficiency of various management options could be demonstrated, even if results should be interpreted with care (as many assumptions had to be made on data and their distributions).     

Influence of diet on the intestinal microflora and meat flavour of intensively‐reared broiler chickens

1. An attempt has been made to modify the composition of the gut flora of broiler chickens by dietary means in order to determine any concurrent changes in meat flavour.

2. Birds given a diet containing an increasing proportion of whole wheat supplemented with fresh green vegetable matter (special diet) were compared with conventionally‐fed controls. At 12 weeks of age those receiving the special diet had 10 to 100‐fold higher counts of Escherichia colt and faecal streptococci in the duodenum and lower small intestine and showed differences in the intestinal incidence of species and biotypes of lactobacilli.

3. Evaluation of cooked breast‐meat samples by a trained sensory panel showed a significant difference in flavour (P < 0.01) between conventional and special‐diet birds which varied from perceptually very slight to slight. The main terms used in distinguishing special‐diet birds from conventional controls included ‘richer’, ‘meatier’ and ‘sweeter’.

4. Storage of plucked, uneviscerated birds at 4 °C for 8 d maintained the flavour difference between the dietary groups but the effect of storage on flavour was greater in both groups of birds than the influence of diet alone. The likely influence on flavour of autolytic changes occurring in the muscle during storage of the birds is discussed.     

The representation and functional composition of carabid and staphylinid beetles in different field boundary types at a farm-scale

At the farm-scale, hedgerow, degraded hedgerow and fence field boundary types were sampled for overwintering carabid and staphylinid beetles. Distinct beetle assemblages were evident and the structural and botanical characteristics of the boundary types were good explanatory factors of the differences. Each field boundary type supported unique species not found elsewhere; nine species were contributed by hedgerows alone and six species each from degraded hedgerows and fences. Using a systematic complementary site selection method we determined that all field boundary types were of equal importance for full representation of carabid and staphylinid species at the farm-scale. Additionally, fence habitats supported generalist predators of crop pests in greatest densities, whilst degraded hedgerows were most valuable in providing refuge to species vulnerable to disturbance and habitat fragmentation. Contrary to expectation, woodland species were not more evident in hedgerows than either degraded boundaries or fence habitat. This study provides empirical evidence that some components of biodiversity and sustainable farming are best maintained by retaining habitat heterogeneity, including features currently considered of limited conservation value.     

Antigenic and morphological differentiation of placental and intestinal isolates of Chlamydia psittaci of ovine origin.

Ewe placental and lamb intestinal isolates of Chlamydia psittaci recovered from flocks affected with ovine enzootic abortion were examined by inclusion morphology, indirect immunofluorescence (IIF) and immunoblot analysis. Chlamydiae recovered from the faeces of sheep from two flocks free of clinical disease were also examined. In cell culture ovine abortion (OA) and intestinal isolates were distinguishable by inclusion development and morphology. Similarly, in two-way IIF tests with one week mouse antisera isolates fell into two distinct groups: abortion or intestinal. Immunoblotting with convalescent sheep abortion antiserum identified 30 out of at least 40 silver staining polypeptides as antigenic both in OA and intestinal isolates. The serum produced a similar reaction pattern to the resolved proteins of each OA isolate, indicating a higher degree of antigenic conservation among these isolates. Considerable cross reactivity between the OA and intestinal isolates was identified, but the serum also showed apparent molecular weight differences between antigens of the two types in the 87-116 kDa, 38-44 kDa and 26-28 kDa regions. Furthermore, the immunoblotting analysis revealed heterogeneity among the intestinal isolates, particularly in antigens between 87-116 kDa and 38-44 kDa.     

ULTRASONOGRAPHY VERSUS RADIOGRAPHY FOR DETECTION OF FLUID IN THE CANINE TYMPANIC BULLA

The tympanic bullae of 20 previously healthy cadaver animals were randomly filled with sterile saline or air. The heads were positioned using tape ties and a rostrocaudal open mouth radiograph taken. The resulting radiographs were assessed by a blinded ECVDI diplomate, with each tympanic bulla being recorded as being either air or fluid filled. Ultrasound examination of the bullae was performed, by a blinded assessor, using a B-mode 5 mHz sector probe (Sonotron-VingMed Sound A/S, PO Box 141, N3191, Horten, Norway) operating at 3 mHz. Each bulla was recorded as being either air or fluid filled. Results of radiography and ultrasonography were each compared to the actual status of the bulla in a chi square analysis. Sensitivity of radiography was 80%, with specificity of 65%. Ultrasonographic sensitivity was 100% and specificity 100%. Ultrasonography may in future provide a cheap, noninvasive, rapid and widely available method for diagnosing otitis media in clinical cases.     

Transcatheter intravascular stent placement to relieve supravalvular pulmonic stenosis

Valvular pulmonic stenosis has been successfully treated in dogs via minimally invasive transcatheter balloon dilation procedures for almost 20 years. Supravalvular pulmonic stenosis however is not amenable to balloon dilation procedures. Although several surgical procedures are described for treatment of pulmonic stenosis, the morbidity and mortality of these procedures are significantly higher than for transcatheter approaches.Two cases of supravalvular pulmonic stenosis are presented, one acquired and one congenital, which were successfully treated with transcatheter intravascular stent placement. The procedure alleviated the stenotic lesion and resolved clinical signs.     

A comparison of cerebral arteriography and cavernous sinus venography in the dog

The technique and relative merits of cerebral arteriography and cavernous sinus venography are reviewed. Of seven cases investigated by cerebral arteriography, only one case showed evidence of abnormality and this was confirmed at post-mortem. Of nine cases investigated by cavernous sinus venography, six cases had positive findings, five of which have subsequently been substantiated pathologically.
Résumé. On passe en revue les techniques et les mérites relatifs de l'artériographie cérébrale et de la veinographie du sinus cavnereux. Sur 7 cas soumis à l'artériographie cérébrale, un seul a presénté des anomalies confirmées à l'autopsie. Sur les 9 cas dans lesquels on a utilisé la veinographie du sinus caverneux, 6 ont donné des résultats positifs et parmi eux, 5 ont reçu une confirmation anatomo-pathologique ultérieure.
Zusammenfassung. Die Methoden und relativen Vorzüge der cerebralen Artériographie und der cavernösen Sinusvenographie werden besprochen. Von den sieben mit cerebraler Artériographie untersuchten Fällen zeigte nur einer Anzeichen von Anomalität, die bei der Autopsie bestätigt wurde. Von neun Fällen, die mit cavernösen Sinusvenographie untersucht wurden, ergaben sechs positive Befunde, von denen fünf später pathologisch bestätigt wurden.